U.S. patent application number 10/444964 was filed with the patent office on 2003-10-23 for imaging apparatus with dynamic range expanded, a video camera including the same, and a method of generating a dynamic range expanded video signal.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Serizawa, Masayuki, Tabei, Kenji.
Application Number | 20030197805 10/444964 |
Document ID | / |
Family ID | 26575536 |
Filed Date | 2003-10-23 |
United States Patent
Application |
20030197805 |
Kind Code |
A1 |
Serizawa, Masayuki ; et
al. |
October 23, 2003 |
Imaging apparatus with dynamic range expanded, a video camera
including the same, and a method of generating a dynamic range
expanded video signal
Abstract
An imaging circuit generates a first video signal with a first
exposure interval and a second video signal with a second exposure
interval substantially at the same time, the second exposure
interval being shorter than the first exposure interval, the first
and second video signals respectively having first and second
dynamic ranges which are different but continues. The first video
signal is synchronized with the second video signal. An exposure
ratio between the first and second exposure intervals is detected.
A gain of the second video signal is adjusted according to the
exposure ratio. A combined video signal is generated from the first
and second video signals according to a mixing control signal
indicative of a mixing ratio between first and second video signals
and levels of the first and second video signals to have an
expanded dynamic range such that the first dynamic range is
connected to the second dynamic range with difference in gains of
the first and second video signals adjusted for linearity. An edge
enhancement signal may be gain-controlled or coring-controlled
according to the mixing control signal or the exposure ratio. The
similar apparatus and method for color signals are also disclosed.
The output dynamic range for a display is limited by a non-linear
process.
Inventors: |
Serizawa, Masayuki;
(Yokohama-shi, JP) ; Tabei, Kenji;
(Sagamihara-shi, JP) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
SUITE 800
1990 M STREET NW
WASHINGTON
DC
20036-3425
US
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
|
Family ID: |
26575536 |
Appl. No.: |
10/444964 |
Filed: |
May 27, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10444964 |
May 27, 2003 |
|
|
|
09187048 |
Nov 6, 1998 |
|
|
|
6593970 |
|
|
|
|
Current U.S.
Class: |
348/362 ;
348/E5.034; 348/E9.01 |
Current CPC
Class: |
H04N 2209/049 20130101;
H04N 5/235 20130101; H04N 9/0451 20180801; H04N 5/35581
20130101 |
Class at
Publication: |
348/362 |
International
Class: |
H04N 005/235 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 1997 |
JP |
JP9-336652 |
Nov 21, 1997 |
JP |
JP9-336653 |
Claims
What is claimed is:
1. An imaging apparatus comprising: imaging means including driving
means for receiving an optical image and generating a first video
signal with a first exposure interval and a second video signal
with a second exposure interval substantially at the same time,
said second exposure interval being shorter than said first
exposure interval, said first and second video signals respectively
having first and second effective detection ranges which are
different but continuous; synchronizing means for synchronizing
said first video signal with said second video signal every
corresponding frames of said first and second video signals;
exposure interval ratio detection means responsive to said driving
means for detecting an exposure ratio between said first and second
exposure intervals; gain adjusting means responsive to said first
and second video signals from said synchronizing means for
adjusting a difference between gains of said first and second video
signals from said synchronizing means in accordance with said
exposure ratio from said exposure interval ratio detection means;
mixing control signal generation means for generating a mixing
control signal indicative of a mixing ratio of said first and
second video signals in accordance with said first and second video
signals from said gain adjusting means; and combining means for
generating and outputting a combined video signal from said first
and second video signals from said gain adjusting means in
accordance with said mixing control signal and levels of said first
and second video signals to have an expanded detection range such
that said first effective detection range is connected to said
second effective detection range.
2. A method of generating a combined video signal from an optical
image comprising the steps of: receiving said optical image and
generating a first video signal with a first exposure interval and
a second video signal with a second exposure interval substantially
at the same time, said second exposure interval being shorter than
said first exposure interval, said first and second video signals
respectively having first and second effective detection ranges
which are different but continuous; synchronizing said first video
signal with said second video signal every corresponding frames of
said first and second video signals; detecting an exposure ratio
between said first and second exposure intervals; adjusting a
difference of gains of the synchronized first and second video
signals in accordance with said exposure ratio; generating a mixing
control signal indicative of a mixing ratio of said first and
second video signals in accordance with said gain-adjusted first
and second video signals; and generating and outputting said
combined video signal from the gain-adjusted first and second video
signals in accordance with said mixing control signal and levels of
the gain-adjusted first and second video signals to have an
expanded dynamic range such that said first effective detection
range is connected to said second effective detection range.
3. An imaging apparatus comprising: imaging means including driving
means for receiving an optical image and generating a first video
signal with a first exposure interval and a second video signal
with a second exposure interval substantially at the same time,
said second exposure interval being shorter than said first
exposure interval, said first and second video signals respectively
having first and second effective detection ranges which are
different but continuous; synchronizing means for synchronizing
said first video signal with said second video signal every
corresponding frames of said first and second video signals; mixing
control signal generation means for generating a mixing control
signal indicative of a mixing ratio of said first and second video
signals in accordance with said first and second video signals;
video signal generation means for generating a combined video
signal from said first and second video signals from said
synchronizing means in accordance with said mixing control signal
and levels of said first and second video signals to have an
expanded dynamic range such that said first effective detection
range is connected to said second effective detection range; edge
enhancement signal generation means for generating an edge
enhancement signal from said combined video signal; edge
enhancement amount control means for controlling an mount of said
edge enhancement signal in accordance with said mixing control
signal; and adding means for adding said edge enhancement signal
from said gain adjusting means and said combined video signal and
outputting an edge-enhanced video signal.
4. A method of generating a combined video signal from an optical
image comprising the steps of: receiving said optical image and
generating a first video signal with a first exposure interval and
a second video signal with a second exposure interval substantially
at the same time, said second exposure interval being shorter than
said first exposure interval, said first and second video signals
respectively having first and second effective detection ranges
which are different but continuous; synchronizing said first video
signal with said second video signal every corresponding frames of
said first and second video signals; generating a mixing control
signal indicative of a mixing ratio of said first and second video
signals in accordance with the synchronized first and second video
signals; generating said combined video signal from the
synchronized first and second video signal in accordance with said
mixing control signal and levels of said first and second video
signals to have an expanded detection range such that said first
effective detection range is connected to said second effective
detection range; generating an edge enhancement signal from said
combined video signal; controlling an amount of said edge
enhancement signal in accordance with said mixing control signal;
and adding the amount-controlled edge enhancement signal and said
combined video signal and outputting an edge-enhanced video
signal.
5. The imaging apparatus as claimed in claim 3, further comprising:
generation means generating a coring amount control signal in
accordance with said mixing control signal; and coring means for
effecting a coring operation to the edge enhancement signal in
accordance with said coring amount control signal.
6. The method as claimed in claim 4, further comprising the steps
of: generating a coring amount control signal in accordance with
said mixing control signal; and effecting a coring operation to
said edge enhancement signal in accordance with said coring amount
control signal.
7. An imaging apparatus comprising: imaging means including driving
means for receiving an optical image and generating a first video
signal with a first exposure interval and a second video signal
with a second exposure interval substantially at the same time,
said second exposure interval being shorter than said first
exposure interval, said first and second video signals respectively
having first and second effective detection ranges which are
different but continuous; synchronizing means for synchronizing
said first video signal with said second video signal every
corresponding frames of said first and second video signals;
exposure ratio detection means responsive to said imaging means for
detecting an exposure ratio between said first and second exposure
intervals; mixing control signal generation means for generating a
mixing control signal indicative of a mixing ratio of said first
and second video signals in accordance with said first and second
video signals; combining means for generating a combined video
signal from said first and second video signals from said
synchronizing means in accordance with said mixing control signal
and levels of said first and second video signals to have an
expanded dynamic range such that said first effective detection
range is connected to said second effective detection range; edge
enhancement signal generation means for generating an edge
enhancement signal from said combined video signal; edge
enhancement amount control means for controlling an amount of said
edge enhancement signal in accordance with said mixing control
signal and said exposure interval ratio; and adding means for
adding said edge enhancement signal from said gain adjusting means
and said combined video signal and outputting an edge-enhanced
video signal.
8. A method of generating a combined video signal from an optical
image comprising the steps of: receiving said optical image and
generating a first video signal with a first exposure interval and
a second video signal with a second exposure interval substantially
at the same time, said second exposure interval being shorter than
said first exposure interval, said first and second video signals
respectively having first and second effective detection ranges
which are different but continuous; synchronizing said first video
signal with said second video signal; detecting an exposure ratio
between said first and second exposure intervals; adjusting a gain
of said second video signal synchronized in accordance with said
exposure ratio every corresponding frames of said first and second
video signals; generating a mixing control signal indicative of a
mixing ratio of the synchronized first and second video signals in
accordance with the gain-adjusted first and second video signals;
generating said combined video signal from the synchronized first
and second video signals in accordance with said mixing control
signal and levels of said first and second video signals to have an
expanded detection range such that said first effective detection
range is connected to said second effective detection range;
generating an edge enhancement signal from said combined video
signal; controlling an amount of said edge enhancement signal in
accordance with said mixing control signal and said exposure ratio;
and adding the gain-adjusted enhancement signal from said gain
adjusting means and said combined video signal and outputting an
edge-enhanced video signal.
9. The imaging apparatus as claimed in claim 7, further comprising:
coring amount control signal generation means for generating a
coring amount control signal in accordance with said mixing control
signal and said exposure ratio; and coring means for effecting a
coring operation to the edge enhanced signal in accordance with
said coring amount control signal from said coring amount control
signal generation means.
10. The method as claimed in claim 8, further comprising the steps
of: generating a coring amount control signal in accordance with
said mixing control signal and said exposure ratio; and effecting a
coring operation to the edge enhancement signal in accordance with
said coring amount control signal.
11. An imaging apparatus comprising: imaging means including
driving means for receiving separated red, green, and blue optical
images and generating first red, first green, and first blue video
signals with a first exposure interval and second red, second
green, and second blue video signals with a second exposure
interval substantially at the same time, said second exposure
interval being shorter than said first exposure interval, said
first red, green, and blue video signals respectively having first
red, first green, and first blue effective detection ranges and
said second red, green, and blue video signals respectively having
second red, second green, and second blue effective detection
ranges which are different from said first red, first green, and
first blue effective detection ranges respectively but continuous;
synchronizing means for synchronizing said first red, first green,
and first blue video signals with second red, second green, and
second blue video signals every corresponding frames of said first
red, first green, and first blue video signals and said second red,
second green, and second blue video signals; exposure interval
ratio detection means responsive to said driving means for
detecting an exposure ratio between said first and second exposure
intervals; gain adjusting means for respectively adjusting
difference between gains of said first red, first green, and first
blue video signals and second red, first, and video signals from
said synchronizing means in accordance with said exposure ratio
from said exposure interval ratio detection means; mixing control
signal generation means for generating red, green, and blue mixing
control signals respectively indicating mixing ratios between said
first red, first green, and first blue video signals and second
red, second green, and second blue video signals in accordance with
said first red, first green, and first blue video signals and
second red, second green, and second blue video signals; and
combining means for generating and outputting combined red, green,
and blue video signals from said first red, first green, and first
blue video signals and second red, second green, and second blue
video signals from said gain adjusting means in accordance with
said red, green, and blue mixing control signals and levels of said
first red, first green, and first blue video signals and second
red, second green, and second blue video signals to have expanded
red, green, and blue detection ranges such that said first red,
first green, and first blue effective detection ranges are
connected to said second red, second green, and second blue video
signals, respectively.
12. The-imaging apparatus as claimed in claim 11, further
comprising: maximum detection means for detecting a maximum level
among said combined red, combined green, and combined blue video
signals for one frame period; and non-linear processing means
responsive to display dynamic range data for generating and
outputting red, green, and blue display signals having non-linear
characteristics such that said maximum level is made equal to or
less than said display dynamic range data when the detected maximum
level is larger than said display dynamic range data and outputting
said combined red, green, and blue video signal as they are when
the detected maximum level is not larger than said display dynamic
range data.
13. A method of generating a combined video signal from an optical
image comprising the steps of: receiving separated red, green, and
blue optical images; generating first red, first green, and first
blue video signals with a first exposure interval and second red,
second green, and second blue video signals with a second exposure
interval substantially at the same time, said second exposure
interval being shorter than said first exposure interval, said
first video signals respectively having first red, first green, and
first blue effective detection ranges, said second video signals
respectively having second red, second green, and second blue
effective detection ranges which are respectively different from
first red, first green, and first blue effective detection ranges
but continuous; synchronizing said first red, first green, and
first blue video signals with second red, second green, and second
blue video signals every corresponding frames of said first red,
first green, and first blue video signals and said second red,
second green, and second blue video signals; detecting an exposure
ratio between said first and second exposure intervals; adjusting
difference between gains of said first red, first green, and first
blue video signals and second red, first, and video signals from
said synchronizing means in accordance with said exposure ratio;
generating red, green, and blue mixing control signals respectively
indicating mixing ratios between said first red, first green, and
first blue video signals and second red, second green, and second
blue video signals in accordance with said first red, first green,
and first blue video signals and second red, second green, and
second blue video signals; and generating and outputting combined
red, green, and blue video signals from said first red, first
green, and first blue video signals and second red, second green,
and second blue video signals from said gain adjusting means in
accordance with said mixing control signals and levels of said
first red, first green, and first blue video signals and second
red, second green, and second blue video signals to have expanded
red, green, and blue detection ranges such that said first red,
first green, and first blue effective detection ranges are
connected to said second red, second green, and second blue video
signals, respectively.
14. The method as claimed in claim 13, further comprising the steps
of: detecting a maximum level among said combined red, third green,
and third blue video signals for one frame period; and generating
and outputting red, green, and blue display signals having
non-linear characteristic in accordance with display dynamic data
and said maximum level such that said maximum level is made equal
to or less than said display dynamic range data when the detected
maximum level is larger than said display dynamic range data and
outputting said combined red, green, and blue video signal as they
are when the detected maximum level is not larger than said display
dynamic range data.
15. A video camera comprising: a lens unit; separation means for
separating an optical image beam into separated red, green, and
blue optical images; imaging means including driving means for
receiving separated red, green, and blue optical images and
generating first red, first green, and first blue video signals
with a first exposure interval and second red, second green, and
second blue video signals with a second exposure interval
substantially at the same time, said second exposure interval being
shorter than said first exposure interval, said first video signals
respectively having first red, first green, and first blue
effective detection ranges, said first and second video signals
respectively having second red, second green, and second blue
effective detection ranges which are different from said first red,
first green, and first blue effective detection ranges but
continuous; synchronizing means for synchronizing said first red,
first green, and first blue video signals with second red, second
green, and second blue video signals every corresponding frames of
said first red, first green, and first blue video signals and said
second red, second green, and second blue video signals; exposure
interval ratio detection means responsive to said driving means for
detecting an exposure ratio between said first and second exposure
intervals; gain adjusting means for adjusting difference between
gains of said first red, first green, and first blue video signals
and second red, first, and video signals from said synchronizing
means in accordance with said exposure ratio from said exposure
interval ratio detection means; mixing control signal generation
means for generating red, green, and blue mixing control signals
respectively indicating mixing ratios between said first red, first
green, and first blue video signals and second red, second green,
and second blue video signals in accordance with said first red,
first green, and first blue video signals and second red, second
green, and second blue video signals; and combining means for
generating and outputting combined red, green, and blue video
signals from said first red, first green, and first blue video
signals and second red, second green, and second blue video signals
from said gain adjusting means in accordance with said mixing
control signals and levels of said first red, first green, and
first blue video signals and second red, second green, and second
blue video signals to have expanded red, green, and blue detection
ranges such that said first red, first green, and first blue
effective detection ranges are connected to said second red, second
green, and second blue video signals, respectively.
16. The camera as claimed in claim 15, further comprising: maximum
detection means for detecting a maximum level among said combined
red, third green, and third blue video signals for one frame
period; and non-linear processing means responsive to display
dynamic range data for generating and outputting red, green, and
blue display signals having non-linear characteristic such that
said maximum level is made equal to or less than said display
dynamic range data when the detected maximum level is larger than
said display dynamic range data and outputting said combined red,
green, and blue video signal as they are when the detected maximum
level is not larger than said display dynamic range data.
17. The imaging apparatus as claimed in claim 1, wherein said gain
adjusting means adjusts said difference between gains of said first
and second video signals from said synchronizing means to provide a
linearity in the expanded detection range.
18. The imaging apparatus as claimed in claim 1, further
comprising: edge enhancement signal generation means for generating
an edge enhancement signal from said combined video signal; edge
enhancement amount control means for controlling an amount of said
edge enhancement signal in accordance with said mixing control
signal; and adding means for adding said edge enhancement signal
from said gain adjusting means and said combined video signal and
outputting an edge-enhanced video signal.
19. The imaging apparatus as claimed in claim 18, wherein said edge
enhancement amount control means controls said amount of said edge
enhancement signal in accordance with said exposure ratio in
addition to said mixing control signal.
20. The imaging apparatus as claimed in claim 1, further
comprising: edge enhancement signal generation means for generating
an edge enhancement signal from said combined video signal; coring
amount control signal generation means for generating a coring
amount control signal in accordance with said mixing control
signal; coring means for effecting a coring operation to the edge
enhanced signal in accordance with said coring amount control
signal from said coring amount control signal generation means; and
adding means for adding said edge enhancement signal from said edge
enhancement signal generation means and said combined video signal
and outputting an edge-enhanced video signal.
21. The imaging apparatus as claimed in claim 20, wherein said
coring amount control signal generation means generates said coring
amount control signal in accordance with said exposure ratio in
addition to said mixing control signal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to an imaging apparatus with its
dynamic range expanded, a video camera including the same, and a
method of generating a dynamic range expanded video signal.
[0003] 2. Description of the Prior Art
[0004] An imaging apparatus for generating a dynamic range expanded
video signal by combining video signals generated substantially at
the same time with different exposure intervals is known. Such an
image apparatus is disclosed in Japanese patent application
provisional publication No. 07131718A. A video signal processing
circuit including an edge enhancement signal generation circuit
generating an edge enhancement signal from a video signal and a
gamma correction circuit for compensating a gamma of the video
signal, wherein the edge enhancement signal is not subjected the
gamma correction and is added to the gamma-corrected video signal
is known. Such a video signal processing circuit is disclosed in
Japanese patent application provisional publication No.
63-209373.
SUMMARY OF THE INVENTION
[0005] The aim of the present invention is to provide a superior
imaging apparatus with dynamic range expanded, a superior video
camera including the same, and a superior method of generating a
dynamic range expanded video signal.
[0006] According to the present invention, a first imaging
apparatus is provided, which comprises: an imager including driving
circuit for receiving an optical image and generating a first video
signal with a first exposure interval and a second video signal
with a second exposure interval substantially at the same time, the
second exposure interval being shorter than the first exposure
interval, the first and second video signals respectively having
first and second effective detection ranges which are different but
continuous; a synchronizing circuit for synchronizing the first
video signal with the second video signal every corresponding
frames of the first and second video signals; an exposure interval
ratio detection circuit responsive to the driving circuit for
detecting an exposure ratio between the first and second exposure
intervals; a gain adjusting circuit responsive to the first and
second video signals from the synchronizing circuit for adjusting a
difference between gains of the first and second video signals from
the synchronizing circuit in accordance with the exposure ratio
from the exposure interval ratio detection circuit for linearity; a
mixing control signal generation circuit for generating a mixing
control signal indicative of a mixing ratio of the first and second
video signals in accordance with the first and second video signals
from the gain adjusting circuit; and a combining circuit for
generating and outputting a combined video signal from the first
and second video signals from the gain adjusting circuit. In
accordance with the mixing control signal and levels of the first
and second video signals to have an expanded detection range such
that the first effective detection range is connected to the second
effective detection range.
[0007] In the first imaging apparatus, the gain adjusting circuit
adjusts the difference between gains of the first and second video
signals from the synchronizing circuit to provide a linearity in
the expanded detection range.
[0008] The first imaging apparatus may further comprise: an edge
enhancement signal generation circuit for generating an edge
enhancement signal from the combined video signal; an edge
enhancement amount control circuit for controlling an amount of the
edge enhancement signal in accordance with the mixing control
signal; and an adding circuit for adding the edge enhancement
signal from the gain adjusting circuit and the combined video
signal and outputting an edge-enhanced video signal. In this case,
the edge enhancement amount control circuit controls the amount of
the edge enhancement signal in accordance with the exposure ratio
in addition to the mixing control signal.
[0009] The first imaging apparatus may further comprise: an edge
enhancement signal generation circuit for generating an edge
enhancement signal from the combined video signal; a coring amount
control signal generation circuit for generating a coring amount
control signal in accordance with the mixing control signal; and a
coring circuit for effecting a coring operation to the edge
enhanced signal in accordance with the coring amount control signal
from the coring amount control signal generation circuit; and an
adding circuit for adding the edge enhancement signal from the edge
enhancement signal generation circuit and the combined video signal
and outputting an edge-enhanced video signal. In this case, the
coring amount control signal generation circuit generates the
coring amount control signal in accordance with the exposure ratio
in addition to the mixing control signal.
[0010] According to the present invention, a first method of
generating a combined video signal from an optical image is
provided which comprises the steps of: receiving the optical image
and generating a first video signal with a first exposure interval
and a second video signal with a second exposure interval
substantially at the same time, the second exposure interval being
shorter than the first exposure interval, the first and second
video signals respectively having first and second effective
detection ranges which are different but continuous; synchronizing
the first video signal with the second video signal every
corresponding frames of the first and second video signals;
detecting an exposure ratio between the first and second exposure
intervals; adjusting a difference in gains of the synchronized
first and second video signal in accordance with the exposure
ratio; generating a mixing control signal indicative of a mixing
ratio of the first and second video signals in accordance with the
gain-adjusted first and second video signals; and generating and
outputting the combined video signal from the gain-adjusted first
and second video signals in accordance with the mixing control
signal and levels of the gain-adjusted first and second video
signals to have an expanded dynamic range such that the first
effective detection range is connected to the second effective
detection range.
[0011] According to the present invention, a second imaging
apparatus is provided which comprises: an imager including a
driving circuit for receiving an optical image and generating a
first video signal with a first exposure interval and a second
video signal with a second exposure interval substantially at the
same time, the second exposure interval being shorter than the
first exposure interval, the first and second video signals
respectively having first and second dynamic ranges which are
different but continuous; a synchronizing circuit for synchronizing
the first video signal with the second video signal every
corresponding frames of the first and second video signals; a
mixing control signal generation circuit for generating a mixing
control signal indicative of a mixing ratio of the first and second
video signals; a video signal generation circuit for generating a
combined video signal from the first and second video signals from
the synchronizing circuit in accordance with the mixing control
signal and levels of the first and second video signals to have an
expanded dynamic range such that the first effective detection
range is connected to the second effective detection range; an edge
enhancement signal generation circuit for generating an edge
enhancement signal from the combined video signal; an edge
enhancement amount control circuit responsive to the driving
circuit for controlling an amount of the edge enhancement signal in
accordance with the mixing control signal; and an adding circuit
for adding the edge enhancement signal from the gain adjusting
circuit and the combined video signal and outputting an
edge-enhanced video signal.
[0012] The second imaging apparatus may further comprise a
generation circuit generating a coring amount control signal in
accordance with the mixing control signal and a coring circuit for
effecting a coring operation to the edge enhancement signal in
accordance with the coring amount control signal.
[0013] According to the present invention, a second method of
generating a combined video signal from an optical image is
provided which comprises the steps of: receiving the optical image
and generating a first video signal with a first exposure interval
and a second video signal with a second exposure interval
substantially at the same time, the second exposure interval being
shorter than the first exposure interval, the first and second
video signals respectively having first and second effective
detection ranges which are different but continuous; synchronizing
the first video signal with the second video signal every
corresponding frames of the first and second video signals;
generating a mixing control signal indicative of a mixing ratio of
the first and second video signals in accordance with the
gain-adjusted first and second video signals; generating the
combined video signal from the synchronized first and second video
signal in accordance with the mixing control signal and levels of
the first and second video signals to have an expanded detection
range such that the first effective detection range is connected to
the second effective detection range; generating an edge
enhancement signal from the combined video signal; controlling an
amount of the edge enhancement signal in accordance with the mixing
control signal; and adding the gain-adjusted edge enhancement
signal and the combined video signal and outputting an
edge-enhanced video signal.
[0014] The second method may further comprise the steps of:
generating a coring amount control signal in accordance with the
mixing control signal; and effecting a coring operation to the edge
enhancement signal in accordance with the coring amount control
signal.
[0015] According to the present invention, a third imaging
apparatus is provided which comprises: an imager including driving
circuit for receiving an optical image and generating a first video
signal with a first exposure interval and a second video signal
with a second exposure interval substantially at the same time, the
second exposure interval being shorter than the first exposure
interval, the first and second video signals respectively having
first and second effective detection ranges which are different but
continuous; a synchronizing circuit for synchronizing the first
video signal with the second video signal every corresponding
frames of the first and second video signals; an exposure ratio
detection circuit responsive to the driving circuit for detecting
an exposure ratio between the first and second exposure intervals;
a mixing control signal generation circuit for generating a mixing
control signal indicative of a mixing ratio of the first and second
video signals in accordance with the first and second video signals
from the synchronizing circuit; a combining circuit for generating
a combined video signal from the first and second video signals
from the synchronizing circuit in accordance with the mixing
control signal and levels of the first and second video signals to
have an expanded dynamic range-such that the first effective
detection range is connected to the second effective detection
range; an edge enhancement signal generation circuit for generating
an edge enhancement signal from the combined video signal; an edge
enhancement amount control circuit for controlling an amount of the
edge enhancement control signal in accordance with the mixing
control signal and the exposure interval ratio; and an adding
circuit for adding the edge enhancement signal from the gain
adjusting circuit and the combined video signal and outputting an
edge-enhanced video signal.
[0016] The third imaging apparatus may further comprise: a coring
amount control signal generation circuit for generating a coring
amount control signal in accordance with the mixing control signal
and the exposure ratio; and a coring circuit for effecting a coring
operation to the edge enhanced signal in accordance with the coring
amount control signal from the coring amount control signal
generation circuit.
[0017] According to the present invention, a third method of
generating a combined video signal from an optical image is
provided which comprises the steps of: receiving the optical image
and generating a first video signal with a first exposure interval
and a second video signal with a second exposure interval
substantially at the same time, the second exposure interval being
shorter than the first exposure interval, the first and second
video signals respectively having first and second effective
detection ranges which are different but continuous; synchronizing
the first video signal with the second video signal; detecting an
exposure ratio between the first and second exposure intervals;
generating a mixing control signal indicative of a mixing ratio of
the synchronized first and second video signals in accordance with
the synchronized first and second video signals; generating the
combined video signal from the synchronized first and second video
signals in accordance with the mixing control signal and levels of
the first and second video signals to have an expanded detection
range such that the first effective detection range is connected to
the second effective detection range; generating an edge
enhancement signal from the combined video signal; controlling an
amount of the edge enhancement signal in accordance with the mixing
control signal and the exposure interval; and adding the
gain-adjusted enhancement signal from the gain adjusting circuit
and the combined video signal and outputting an edge-enhanced video
signal.
[0018] The third method may further comprise the steps of:
generating a coring amount control signal in accordance with the
mixing control signal and the exposure ratio; and effecting a
coring operation to the edge enhancement signal in accordance with
the coring amount control signal.
[0019] According to the present invention, a fourth imaging
apparatus is provided which comprises: an imager including driving
circuit for receiving separated red, green, and blue optical images
and generating first red, first green, and first blue video signals
with a first exposure interval and second red, second green, and
second blue video signals with a second exposure interval
substantially at the same time, the second exposure interval being
shorter than the first exposure interval, the first red, green, and
blue video signals respectively having first red, first green, and
first blue effective detection ranges which are different from the
second red, second green, and blue but continuous; a synchronizing
circuit for synchronizing the first red, first green, and first
blue video signals with second red, second green, and second blue
video signals every corresponding frames of the first red, first
green, and first blue video signals and the second red, second
green, and second blue video signals, respectively; an exposure
interval ratio detection circuit responsive to the driving circuit
for detecting an exposure ratio between the first and second
exposure intervals; a gain adjusting circuit for respectively
adjusting difference between gains of the first red, first green,
and first blue video signals and second red, first, and video
signals from the synchronizing circuit in accordance with the
exposure ratio from the exposure interval ratio detection circuit;
a mixing control signal generation circuit for generating red,
green, and blue mixing control signals respectively indicating
mixing ratios between the first red, first green, and first blue
video signals and second red, second green, and second blue video
signals in accordance with the first red, first green, and first
blue video signals and second red, second green, and second blue
video signals; and a combining circuit for generating and
outputting combined red, green, and blue video signals from the
first red, first green, and first blue video signals and second
red, second green, and second blue video signals from the gain
adjusting circuit in accordance with the red, green, and blue
mixing control signals and levels of the first red, first green,
and first blue video signals and second red, second green, and
second blue video signals to have expanded red, green, and blue
detection ranges such that the first red, first green, and first
blue effective detection ranges are connected to the second red,
second green, and second blue video signals, respectively.
[0020] The fourth imaging apparatus may further comprise: a maximum
detection circuit for detecting a maximum level among the combined
red, combined green, and combined blue video signals for one frame
period; and a non-linear processing circuit responsive to display
dynamic range data for generating and outputting red, green, and
blue display signals respectively having non-linear characteristics
such that the maximum level is made equal to or less than the
display dynamic range data when the detected maximum level is
larger than the display dynamic range data and outputting the
combined red, green, and blue video signal as they are when the
detected maximum level is not larger than the display dynamic range
data.
[0021] According to the present invention, a fourth method of
generating a combined video signal from an optical image is
provided which comprises the steps of: receiving separated red,
green, and blue optical images; generating first red, first green,
and first blue video signals with a first exposure interval and
second red, second green, and second blue video signals with a
second exposure interval substantially at the same time, the second
exposure interval being shorter than the first exposure interval,
the first red, first green, and first blue video signals
respectively having first red, first green, and first blue
effective detection ranges and the second red, second green, and
second blue video signals respectively having second red, second
green, and second blue effective detection ranges which are
different from the first red, first green, and first blue effective
detection ranges but continuous; synchronizing the first red, first
green, and first blue video signals with second red, second green,
and second blue video signals every corresponding frames of the
first red, first green, and first blue video signals and the second
red, second green, and second blue video signals, respectively;
detecting an exposure ratio between the first and second exposure
intervals; adjusting difference between gains of the first red,
first green, and first blue video signals and second red, second
green, and second blue video signals from the synchronizing circuit
in accordance with the exposure ratio; generating red, green, and
blue mixing control signals respectively indicating mixing ratios
between the first red, first green, and first blue video signals
and second red, second green, and second blue video signals; and
generating and outputting combined red, green, and blue video
signals from the first red, first green, and first blue video
signals and second red, second green, and second blue video signals
from the gain adjusting circuit in accordance with the red, green,
and blue mixing control signals and levels of the first red, first
green, and first blue video signals and second red, second green,
and second blue video signals to have expanded red, green, and blue
detection ranges such that the first red, first green, and first
blue effective detection ranges are connected to the second red,
second green, and second blue video signals, respectively.
[0022] The fourth method may further comprise the steps of:
detecting a maximum level among the combined red, combined green,
and combined blue video signals for one frame period; and
generating and outputting red, green, and blue display signals
having non-linear characteristics in accordance with display
dynamic data and the maximum level such that the maximum level is
made equal to or less than the display dynamic range data when the
detected maximum level is larger than the display dynamic range
data and outputting the combined red, green, and blue video signal
as they are when the detected maximum level is not larger than the
display dynamic range data.
[0023] According to the present invention, a video camera is
provided which comprises: a lens unit; separation unit for
separating an optical image beam into separated red, green, and
blue optical images; an imaging unit including driving circuit for
receiving separated red, green, and blue optical images and
generating first red, first green, and first blue video signals
with a first exposure interval and second red, second green, and
second blue video signals with a second exposure interval
substantially at the same time, the second exposure interval being
shorter than the first exposure interval, the first red, first
green, and first blue video signals respectively having first red,
first green, and first blue effective detection ranges, the second
red, second green, and second blue video signals respectively
having second red, second green, and second blue effective
detection ranges which are different from first red, first green,
and first blue effective detection ranges respectively but
continuous; a synchronizing circuit for synchronizing the first
red, first green, and first blue video signals with second red,
second green, and second blue video signals every corresponding
frames of the first red, first green, and first blue video signals
and the second red, second green, and second blue video signals,
respectively; an exposure interval ratio detection circuit
responsive to the driving circuit for detecting an exposure ratio
between the first and second exposure intervals; a gain adjusting
circuit for respectively adjusting difference between gains of the
first red, first green, and first blue video signals and second
red, first, and video signals from the synchronizing circuit in
accordance with the exposure ratio from the exposure interval ratio
detection circuit; a mixing control signal generation circuit for
generating red, green, and blue mixing control signals respectively
indicating mixing ratios between the first red, first green, and
first blue video signals and second red, second green, and second
blue video signals; and a combining circuit for generating and
outputting combined red, green, and blue video signals from the
first red, first green, and first blue video signals and second
red, second green, and second blue video signals from the gain
adjusting circuit in accordance with the red, green and blue mixing
control signals and levels of the first red, first green, and first
blue video signals and second red, second green, and second blue
video signals to have expanded red, green, and blue detection
ranges such that the first red, first green, and first blue
effective detection ranges are connected to the second red, second
green, and second blue video signals, respectively.
[0024] The camera may further comprise: a maximum detection circuit
for detecting a maximum level among the combined red, combined
green, and combined blue video signals for one frame period; and a
non-linear processing circuit responsive to display dynamic range
data for generating and outputting red, green, and blue display
signals having non-linear characteristics such that the maximum
level is made equal to or less than the display dynamic range data
when the detected maximum level is larger than the display dynamic
range data and outputting the combined red, green, and blue video
signal as they are when the detected maximum level is not larger
than the display dynamic range data.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The object and features of the present invention will become
more readily apparent from the following detailed description taken
in conjunction with the accompanying drawings in which:
[0026] FIG. 1 is a block diagram of an imaging apparatus of a first
embodiment;
[0027] FIG. 2 is a block diagram of the first embodiment showing
the structure of the synchronizing circuit shown in FIG. 1;
[0028] FIGS. 3A to 3E are timing charts of the first embodiment for
illustrating the synchronizing operation;
[0029] FIG. 4 is a time chart of the first embodiment showing the
exposure interval identification signal shown in FIG. 1;
[0030] FIG. 5 is a time chart of the first embodiment showing the
gain control signal shown in FIG. 1;
[0031] FIGS. 6A to 6C are graphical drawings of the first
embodiment showing the gain-adjusting and combining operations;
[0032] FIGS. 7A to 7C are graphical drawings of the first
embodiment showing another example of the gain-adjusting and
combining operations;
[0033] FIG. 8 is a block diagram of an imaging apparatus of a
second embodiment;
[0034] FIGS. 9A and 9B are graphical drawings of the second
embodiment;
[0035] FIG. 10 is a block diagram of an imaging apparatus of a
third embodiment;
[0036] FIGS. 11A to 11D are graphical drawings of the third
embodiment;
[0037] FIG. 12 is a block diagram of an imaging apparatus of a
fourth embodiment;
[0038] FIG. 13 is a block diagram of an imaging apparatus of a
fifth embodiment;
[0039] FIG. 14 is a block diagram of an imaging apparatus of a
sixth embodiment;
[0040] FIG. 15 is a block diagram of an imaging apparatus of a
seventh embodiment;
[0041] FIGS. 16 and 17 are graphical drawings of the seventh
embodiment of this invention illustrating the dynamic range
compression operation;
[0042] FIG. 18 is a block diagram of the non-linear processing
circuit of the seventh embodiment; and
[0043] FIGS. 19A to 19C are graphical drawings of the seventh
embodiment illustrating the non-linear processing.
[0044] The same or corresponding elements or parts are designated
with like references throughout the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0045] (First Embodiment)
[0046] FIG. 1 is a block diagram of an imaging apparatus of a first
embodiment. An imager 1010 receives an optical image thereon
through a lens unit 10 and alternatively generating a long exposure
video signal with a first exposure interval and a short interval
exposed video signal with a second exposure interval substantially
at the same time (at slightly different timings, i.e., consecutive
two frames) under control by a driving circuit 1020. The second
exposure interval is shorter than the first exposure interval. The
long exposure video signal and the short exposure video signal
respectively have first and second effective detection ranges 11
and 12. A pre-processing circuit 1030 effects pre-processing the
long exposure video signal and short exposure video signal. The
pre-processing circuit 1030 includes a CDS circuit (not shown) for
cancelling noise components in the analog long exposure video
signal and the analog short exposure video signal from the imager
1010 by correlation double sampling, an automatic gain controlled
amplifier (not shown) for amplifying the long exposure video signal
and the short exposure video signal from the CDS circuit with the
gain automatically controlled, a clamp circuit for clamping the
output of the automatic gain controlled amplifier for inputting it
to the following a/d converter 1040. The a/d converter 1040
a/d-converts the long exposure video signal and the short exposure
video signal into a digital long exposure video signal and a
digital short exposure video signal. The output 1041 of the a/d
converter 1040 is supplied to a synchronizing circuit 1050.
[0047] The synchronizing circuit 1050 synchronizes the digital long
exposure video signal with the digital short exposure video signal
and outputs the digital long exposure video signal and the digital
short exposure video signal in parallel at the same time with the
slight time different adjusted.
[0048] An exposure ratio detection circuit 1140 responsive to the
driving circuit 1020 detects an exposure ratio between the first
and second exposure intervals and outputs a gain control signal
1141. A gain adjusting circuit 1150 adjusts a difference between
gains of the first and second video signals from the synchronizing
circuit 1050 in accordance with the exposure ratio in the gain
control signal 1141 from the exposure ratio detection circuit 1140,
that is, a gain of the short exposure video signal from the
synchronizing circuit 1050 is adjusted.
[0049] A video signal combining circuit 1080 includes a mixing
control signal generation circuit 1083 for generating a mixing
control signal indicative of a mixing ratio k between the long
exposure video signal and the short exposure video signals and
combines the long exposure signal from the synchronizing circuit
1050 with the short exposure video signal from the gain adjusting
circuit 1150 in accordance with the mixing control signal 1082
shown in FIG. 7B and levels of the long exposure video signal and
the gain adjusted short exposure video signal to have an expanded
detection range such that the first effective detection range 11 is
connected to the second effective detection range 12. The combined
video signal 1080 shows a linearity because the gain of the short
exposure video signal 1070 is adjusted.
[0050] The combined video signal 1081 is supplied to a gamma
adjusting circuit 1090 and to an edge enhancement signal generation
circuit 1100. The gamma adjusting circuit 1090 adjusts the gamma of
the combined video signal 1081. The edge enhancement signal
generation circuit 1100 generates an edge enhancement signal from
the combined video signal 1081 and supplies the edge enhancement
signal to a coring circuit 1110. The coring circuit 1110 removes
noise components of which levels less than a predetermined level
and supplies the edge enhancement signal to a multiplexer 1120. The
multiplexer 1120 multiply the edge enhancement signal with an edge
enhancement control signal and supplies the edge enhancement signal
to an adder 1130. The adder 1130 adds the edge enhancement signal
from the multiplexer 1120 to the gamma-adjusted video signal 1091
to generate an output video signal 1131. The lens unit 10 is
further provided to the imaging apparatus to provide a video
camera.
[0051] FIG. 2 is a block diagram of the first embodiment showing
the structure of the synchronizing circuit shown in FIG. 1. The
synchronizing circuit 1050 includes a memory for storing the output
of the a/d converter 1041, a selector 10513 for outputting either
of the output 1041 of the a/d converter or the output 10512 of the
memory 10511 in accordance with an exposure interval identification
signal 1021 from the driving circuit 1020 to selectively output the
long exposure video signal 1060, and a selector 10514 for
outputting either of the output 1041 of the a/d converter or the
output 10512 of the memory 10511 in accordance with the exposure
interval identification signal 1021 from the driving circuit 1020
to selectively output the short exposure video signal 1060.
[0052] FIGS. 3A to 3E are timing charts of the first embodiment for
illustrating the synchronizing operation by the synchronizing
circuit 1050.
[0053] The imager 1010 alternately outputs the long exposure video
signal and the short exposure video signal as shown in FIG. 3A as
the output 1041 of the a/d converter 1040. The memory 10511 outputs
the output 1041 of the a/d converter 1040 with one frame delay.
Therefore, one frame of the short exposure video signal on the line
10515 is synchronized with the corresponding frame of the long
exposure video signal from the memory 10511. For the next frame
interval, the long exposure video signal on the line 10515 is
synchronized with the corresponding frame of the short exposure
video signal from the memory 10511. This operation is repeated as
shown in FIGS. 3A and 3B. The exposure interval identification
signal 1021 changes its output level between "2" and "64" every
frame (field) as shown in FIG. 3C. The selector 10513 performs the
switching operation to only output the long exposure video signal
1060 continuously as shown in FIG. 3E. The selector 10514 performs
the switching operation to only output the short exposure video
signal 1070 continuously, as shown in FIG. 3D. A frame of the short
exposure video signal from the selector 10514 is synchronous with
the corresponding frame of the long exposure video signal 1060 from
the selector 10513 as shown in FIGS. 3D and 3E.
[0054] FIG. 4 is a time chart of the first embodiment showing the
exposure interval identification signal 1021. The driving circuit
1020 generates the exposure interval identification signal 1021
alternately showing a high level value of "64" for the long
exposure interval and a low level value of "2" for the short
exposure interval as shown in FIG. 4.
[0055] FIG. 5 is a time chart of the first embodiment showing the
gain control signal 1141. The exposure ratio detection circuit 1140
detects the exposure ratio of "32" from the high level value of
"64" for the long exposure interval (frame) and the low level value
of "2" for short exposure interval (frame) as shown in FIG. 5.
[0056] FIGS. 6A to 6C are graphical drawings of the first
embodiment showing the gain-adjusting and combining operations.
[0057] As shown in FIG. 6A, a level of the long exposure video
signal 1060 increases with the amount of received light up to a
saturation level (SAT) at a saturation amount. After (larger) the
saturation amount the level of the long exposure video signal 1060
is constant. The long exposure video signal saturates with a
relatively low amount of light because the exposure interval is
relatively long. On the other hand, at the dark level range, the
noise level is relatively low. Therefore, the long exposure video
signal has the first effective detection range 11.
[0058] The short exposure video signal 1070, as shown in FIG. 6B, a
level of the short exposure video signal 1070 increases with the
amount of received light up to the saturation level at with a low
gamma 7. The short exposure video signal saturates with a
relatively high amount of light because the exposure interval is
relatively short. On the other hand, at the dark level range, the
noise level is relatively high. Therefore, the short exposure video
signal has the second effective detection range 12.
[0059] As shown in FIG. 6C, the long exposure video signal 1060 is
combined with the short exposure video signal 1070 to provide an
expanded detection range 13.
[0060] FIGS. 7A to 7C are graphical drawings of the first
embodiment showing another example of the gain-adjusting and
combining operations.
[0061] FIG. 7B shows the mixing control signal 1083. The mixing
control signal 1082 represents the mixing ratio k=0 at the long
exposure region 15, the mixing ratio k=1 at the short exposure
region 17, and the mixing ratio proportionally increases from k=0
to k=1 at mixing region 16.
[0062] The long exposure video signal is modified by ratio (1-k) at
the mixing region 16 and the short exposure video signal is
modified by mixing ratio k at the mixing ratio 16 as shown in FIG.
7A. The combining circuit 1080 combines the short exposure video
signal from the gain adjusting circuit 1150 with the short exposure
video signal 1060 by adding the modified long exposure video signal
to the short exposure video signal as shown in FIGS. 7A and 7C to
provide the combined video signal with an expanded detection range
13 such that the first effective detection range 11 is connected to
the second effective detection range 12.
[0063] In this embodiment the gain of the short exposure video
signal is adjusted by the gain adjusting circuit 1150. However, it
is also possible to adjust the gain of the long exposure video
signal to match its gamma to that of the short exposure video
signal.
[0064] (Second Embodiment)
[0065] FIG. 8 is a block diagram of an imaging apparatus of a
second embodiment.
[0066] The imaging apparatus of the second embodiment has
substantially the same structure as that of the first embodiment.
The difference is that the gain adjustment circuit 1150 and the
exposure ratio detection circuit 1140 are omitted and an edge
enhancement amount control signal generation circuit 1160 and a
multiplier 1170 are further provided.
[0067] FIGS. 9A and 9B are graphical drawings of the second
embodiment. FIG. 9A shows the mixing control signal which is also
shown in FIG. 7A. FIG. 9B shows an edge enhancement amount control
signal 1161.
[0068] The edge enhancement amount control circuit 1160 generates
the edge enhancement amount control signal 1161 in accordance with
the mixing control signal 1082 as shown in FIGS. 9A and 9B.
[0069] The multiplier 1170 controls the amount of the edge
enhancement signal 1101 in accordance with the edge enhancement
amount control signal 1161 and supplies the edge enhancement signal
subjected to the edge enhancement amount controlling to the coring
processing circuit 1110. The edge enhancement amount control signal
1161 at the long exposure region 15 indicates a coefficient of "1"
for the multiplier 1170 and a coefficient of "2" at the short
exposure region 17 for example. Therefore, the edge enhancement
signal is controlled to have a larger edge enhancement signal at
the short exposure ratio 17 by the multiplier 1170.
[0070] In this embodiment, the gain adjusting circuit 1150 and the
exposure ratio detection circuit 1140 are omitted. However, it is
also possible that these circuits are further provided to the
imaging apparatus of the second embodiment as similar to the first
embodiment.
[0071] (Third Embodiment)
[0072] FIG. 10 is a block diagram of an imaging apparatus of a
third embodiment.
[0073] The imaging apparatus of the third embodiment has
substantially the same structure as that of the second embodiment.
The difference is that a coring amount control circuit 1180 and a
multiplier 1190 are further provided and an amount of coring can be
controlled, that is, a coring circuit 1112 is provided.
[0074] FIGS. 11A to 11D are graphical drawings of the third
embodiment, wherein FIG. 11A shows the mixing control signal 1082
which is also shown in FIG. 7A.
[0075] The coring amount control circuit 1180 generates the coring
amount control signal 1181 in accordance with the mixing control
signal 1082.
[0076] The multiplier 1190 multiplies the coring amount control
signal 1181 with a coefficient and supplies a final coring amount
control signal to the coring circuit 1112. Therefore, noise
components in the edge enhancement signal is controlled by the
coring circuit 1112.
[0077] FIG. 11C shows the case that the coring amount is "1" and
FIG. 11D shows the case that the coring amount is "1.5" Then, the
noise components in the edge enhanced video signal at the short
exposure region 17 which is conspicuous in the reproduced image is
suppressed, so that the noise in the output video signal is
improved.
[0078] In this embodiment, the gain adjusting circuit 1150 and the
exposure ratio detection circuit 1140 are omitted. However, it is
also possible that these circuits are further provided to the
imaging apparatus of the third embodiment as similar to the first
embodiment.
[0079] (Fourth Embodiment)
[0080] FIG. 12 is a block diagram of an imaging apparatus of a
fourth embodiment.
[0081] The imaging apparatus of the fourth embodiment has
substantially the same structure as that of the second embodiment.
The difference is that the exposure ratio detection circuit 1140
and a multiplier 1200 are further provided.
[0082] The multiplier 1200 controls the edge enhancement amount
control signal 1161 in accordance with the gain control signal 1141
indicating the exposure ratio between the long exposure interval
and the short exposure interval. The total amount of the edge
enhancement signal is controlled, that is, weighted, by the
multiplier 1170 in accordance with the edge enhancement amount
control signal derived from the mixing control signal 1082 and the
gain control signal 1141 derived from the exposure ratio. Then, the
edges at the short exposure region which tends to be flat because
of the short exposure can be enhanced further.
[0083] In this embodiment, the gain adjusting circuit 1150 is
omitted. However, it is also possible that the gain adjusting
circuit 1150 are further provided to the imaging apparatus of the
fourth embodiment as similar to the first embodiment. Moreover, the
edge enhancement amount control circuit 1160 can be omitted as the
modification of this embodiment.
[0084] (Fifth Embodiment)
[0085] FIG. 13 is a block diagram of an imaging apparatus of a
fifth embodiment.
[0086] The imaging apparatus of the fifth embodiment has
substantially the same structure as that of the fourth embodiment.
The difference is that a multiplier 1210 and the coring amount
control circuit 1180 and the multiplier 1190 which are used in the
third embodiment are further provided.
[0087] The coring amount control circuit 1180 generates the coring
amount controls signal 1181 in accordance with the mixing control
signal 1082 as mentioned in the third embodiment. The multiplier
1210 controls the coring amount control signal 1181 in accordance
with the gain control signal 1141 indicating the exposure ratio
between the long exposure interval and the short exposure interval.
The second coring amount control signal 1211 is controlled, that
is, weighted, by the multiplier 1210 in accordance with the coring
amount control signal 1181 derived from the mixing control signal
1082 and the gain control signal 1141 derived from the exposure
ratio. Noise components in the edge enhancement signal from the
multiplier 1170 is suppressed by the coring circuit 1112.
[0088] Then, the edges at the short exposure region which tends to
be flat because of the short exposure will be enhanced further and
the noise component coring at the short exposure region which tends
to be flat because of the short exposure can be enhanced further by
providing the edge enhancement control circuit 1160. Moreover, the
noise components in the edge enhanced video signal at the short
exposure region 17 which is conspicuous in the reproduced image is
suppressed, so that the noise in the output video signal is
improved.
[0089] In this embodiment, the gain adjusting circuit 1150 is
omitted. However, it is also possible that the gain adjusting
circuit 1150 are further provided in the imaging apparatus of the
fifth embodiment as similar to the first embodiment. Moreover, it
is also possible as modifications of this embodiment that either of
the edge enhancement amount control circuit 1160 and the
multipliers 1170 and 1200 or the coring amount control circuit 1180
and the multipliers 1190 and 1210 are omitted.
[0090] (Sixth Embodiment)
[0091] FIG. 14 is a block diagram of an imaging apparatus of a
sixth embodiment.
[0092] The imaging apparatus of the sixth embodiment has
substantially the same structure as that of the first embodiment.
The difference is that a prism unit 1000 for separating the
incident image into color images, that is, a red image, a green
image, and a blue image is further provided and the imagers 1010
respectively receives the red image, the green image, and a blue
image, and the processing circuits, each including the
pre-processing circuit 1030, the a/d converter 1040, the
synchronizing circuit 1050, the gain adjusting circuit 1110, the
combining circuit 1080, are provided for the red, green, and blue
images respectively, and camera processing circuit 1090 for
processing the respective color video signal is further provided.
For color separation, dichroic mirror units may be used instead the
prism unit 1000.
[0093] The imager 1010 of each color receives an optical image from
the prism 1000 and generates a first video signal with a first
exposure interval and a second video signal with a second exposure
interval substantially at the same time, the second exposure
interval being shorter than the first exposure interval, the first
and second video signals respectively having first and second
effective detection ranges 11 and 12. The synchronizing circuit
1050 for each color synchronizes the first video signal with the
second video signal. The exposure interval ratio detection circuit
1100 responsive to the driving circuit 1020 detects an exposure
ratio between the first and second exposure intervals. The gain
adjusting circuit 1110 for each color adjusts the gain of the
second video signal from the synchronizing circuit 1050 in
accordance with the exposure ratio. The mixing control signal
generation 1083 for each color generates a mixing control signal
indicative of a mixing ratio of the first and second video signals.
The combining circuit 1080 for each color generates a combined
video signal from the first and second video signals in accordance
with the mixing control signal and levels of the first and second
video signals to have an expanded detection range such that the
first effective detection range is connected to the second
effective detection range as described in the first embodiment.
[0094] The camera processing circuit 1090 processes the combined
video signals 1081 of red, green, and blue color to generates
output red signal, an output green signal, and an output blue
signal.
[0095] In this embodiment, the second to fifth embodiments are
applicable to the imaging apparatus of the sixth embodiment.
[0096] (Seventh Embodiment)
[0097] FIG. 15 is a block diagram of an imaging apparatus of a
seventh embodiment.
[0098] The imaging apparatus of the seventh embodiment has
substantially the same structure as that of the sixth embodiment.
The difference is that a max detection circuit 1130, non-linear
processing circuits 1120, and a display dynamic range setting
circuit 1140 are further provided.
[0099] The display dynamic setting circuit 1140 generates or
receive and supplies data 1141 of display dynamic range (DISPMAX).
The max detection circuit 1130 detects the maximum level among the
third red, third green, and third blue video signals for one frame
period. The non-linear processing circuits 1120 responsive to
display dynamic range data (DISPMAX) 1141 generates and outputs
red, green, and blue display signals having non-linear
characteristics such that the maximum level is made equal to or
less than the display dynamic range data when the detected maximum
level is larger than the display dynamic range data and outputs the
combined red, green, and blue video signal as they are when the
detected maximum level is not larger than the display dynamic range
data.
[0100] If the dynamic range of a display apparatus receiving the
output red, blue, and green signals from this imaging apparatus is
smaller than than the dynamic range of the output red, blue, and
green signals, it is necessary to compress the dynamic range of the
output the output red, blue, and green signals.
[0101] The non-linear processing circuit 1120 compress the dynamic
range of the combined video signal to obtain a display video signal
in accordance with the detected maximum (highest high light) level
among the third red, third green and third blue video signals for
one frame period, saturation data, and the display dynamic range
setting data (DISPMAX) 1141 by internally dividing operation.
[0102] FIGS. 16 and 17 are graphical drawings of the seventh
embodiment of this invention illustrating the dynamic range
compression operation.
[0103] It is assumed that the display dynamic range (DISPMAX) 1141
is 20. and the maximum value (RGBMAX) is 25. The characteristic
(gradation characteristic) curve of the combined video signals 1081
are bent above the saturation level (SAT). In fact, the level of
the range-compressed video signal is provided by the internally
dividing the level of the combined video signal using the maximum
(RGBMAX), the saturation level (SAT), and the display dynamic range
setting data (DISPMAX) 1141.
[0104] The maximum detection circuit 1130 detects a maximum level
among the combined video signals 1081 of red, green, and blue for
one frame and supplies the maximum level (RGBMAX) 1131 to the
non-liner processing circuits 1120. The non-linear processing
circuit 1120 generates the range-compressed video data in
accordance with the detected maximum value, the saturation data,
and the display range (DISPMAX) 1141.
[0105] As shown in FIG. 16, level A of the combined video signal is
shifted to A" and level S is shifted to S"(=RGBMAX=DISPMAX) to
prevent saturation. However, if level A is smaller than the
saturation level (SAT), the non-linear processing is not executed,
that is, A=A".
[0106] More specifically, if level A is more than the saturation
level (SAT), assuming that n is a control efficient n for
controlling the non-linear characteristic curve, the level A" after
non-linear processing is given as follows:
[0107] When RGBMAX-DISPMAX.gtoreq.0 AND A.gtoreq.SAT,
.alpha.A=(A-SAT)/(RGBMAX-SAT)
A"=A-{(.alpha.A).sup.n.times.(RGBMAX-DISPMAX)}.
[0108] When RGBMAX-DISPMAX.gtoreq.0 AND A<SAT,
.alpha.A=0
A"=A
[0109] When RGBMAX-DISPMAX<0,
.alpha.A=0
A"=A
[0110] FIG. 17 shows the curves for providing the non-liner
characteristic when the control coefficient n is varied from one to
three.
[0111] FIG. 18 is a block diagram of the non-linear processing
circuit 1120 of the seventh embodiment.
[0112] The non-liner processing circuit 1120 includes a judging
circuit 20, subtractors 21 to 24, multipliers 25 and 26, a divider
27, switches 28 and 29 and generates a non-linear video signal 1121
in response to the combined video signal 1081, the maximum value
1131, the saturation data 1082, and a display maximum value 1141.
The control efficient n for the non-liner characteristic is
determined by the number of the multipliers 25 and connections
around the multipliers 25.
[0113] The display dynamic range (DISPMAX) 1141 may be generated by
a ROM or a RAM storing the display dynamic range (DISPMAX) 1141,
manually set, or sent from the display apparatus to be connected.
Moreover, the saturation value SAT can be decreased as desired by
an operator.
[0114] FIGS. 19A to 19C are graphical drawings of the seventh
embodiment illustrating the non-linear processing.
[0115] It is assumed that the display dynamic range (DISPMAX)
1141=20, the maximum level among the red, green, and blue video
signals (RGBMAX)=25, and the situation level (SAT) of the long
exposure video signal=3 and that the red, green, and blue video
signals respectively show levels R:G:B=20:5:25. The level of the
red video signal is shifted from 20 to 17 by the non-linear
processing, the level of the green video signal remains about 5
because the original level "5" is near the cut point "3" which is
the saturation level, and the level of the blue video signal is
shifted from 25 to 20 by the non-linear processing. Then, that is,
the output levels of the non-linear circuits 1120 are
R:G:B=17:5:20, so that saturation in the display apparatus to be
connected to this imaging apparatus is prevented and the ratio of
levels of the red, green, and blue video signals, that is, a tone
of color, is substantially maintained.
[0116] The second to fifth embodiments are applicable to the
imaging apparatus of the seventh embodiment.
* * * * *