U.S. patent application number 11/055117 was filed with the patent office on 2005-09-08 for electronic still camera and method of image acquisition of electronic still camera.
This patent application is currently assigned to NIKON CORPORATION. Invention is credited to Ide, Hisato.
Application Number | 20050195285 11/055117 |
Document ID | / |
Family ID | 34909198 |
Filed Date | 2005-09-08 |
United States Patent
Application |
20050195285 |
Kind Code |
A1 |
Ide, Hisato |
September 8, 2005 |
Electronic still camera and method of image acquisition of
electronic still camera
Abstract
A photography mode selecting section allows a photographer to
select continuous photographing. An imaging section captures an
image of a subject. An area setting section detects a photographic
subject based on a photographic image captured by the imaging
section for every photographing in the continuous photographing,
and sets the size and position of a photographic subject area
including the detected photographic subject, when the continuous
photographing is selected by the photography mode selecting
section. A memory section stores an image inside the photographic
subject area as a photographic subject image. Consequently, in
continuous photographing of a moving body, the size of the
photographic subject area for every photographing in the continuous
photographing can be changed according to change in the size of the
image of the moving body with respect to an image screen of the
imaging section, thereby preventing wasteful usage of a memory area
of the memory section.
Inventors: |
Ide, Hisato; (Setagaya-ku,
JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
NIKON CORPORATION
Chiyoda-ku
JP
|
Family ID: |
34909198 |
Appl. No.: |
11/055117 |
Filed: |
February 11, 2005 |
Current U.S.
Class: |
348/208.99 |
Current CPC
Class: |
H04N 5/772 20130101;
H04N 5/23296 20130101 |
Class at
Publication: |
348/208.99 |
International
Class: |
H04N 005/228 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 4, 2004 |
JP |
2004-060341 |
Claims
What is claimed is:
1. An electronic still camera comprising: a photography mode
selecting section allowing a photographer to select continuous
photographing; an imaging section capturing an image of a subject;
an area setting section detecting a photographic subject based on a
photographic image captured by said imaging section for every
photographing in the continuous photographing, and setting the size
and position of a photographic subject area including the detected
photographic subject, when the continuous photographing is selected
by said photography mode selecting section; and a memory section
storing an image inside the photographic subject area as a
photographic subject image.
2. The electronic still camera according to claim 1, wherein said
area setting section detects a moving photographic subject based on
a difference between a photographic image captured at the time of
previous photographing and a photographic image captured at the
time of current photographing in the continuous photographing.
3. The electronic still camera according to claim 1, wherein said
area setting section divides the photographic image into plural
areas, and sets the size and position of the photographic subject
area based on luminance information of the respective areas.
4. The electronic still camera according to claim 1, wherein said
area setting section divides the photographic image into plural
areas, and sets the size and position of the photographic subject
area based on contrast information of the respective areas.
5. The electronic still camera according to claim 1, wherein said
area setting section sets the size of the photographic subject area
to be equal to or greater than a predetermined value which is held
in advance, irrespective of the size of a moving photographic
subject.
6. The electronic still camera according to claim 1, wherein said
memory section stores the position of the photographic subject area
with respect to an image screen of said imaging section, together
with the photographic subject image.
7. The electronic still camera according to claim 1, wherein said
area setting section uses a predetermined area which is held in
advance, as the photographic subject area, when a moving
photographic subject cannot be detected.
8. The electronic still camera according to claim 1, further
comprising: a shutter speed changing section changing shutter
speed, wherein said area setting section limits the size of the
photographic subject area in response to increase in the shutter
speed.
9. The electronic still camera according to claim 1, further
comprising: a continuous photographing speed changing section
changing a photographing interval of the continuous photographing,
wherein said area setting section limits the size of the
photographic subject area in response to shortening of the
photographing interval of the continuous photographing.
10. The electronic still camera according to claim 1, further
comprising: a focus detecting point decision section deciding a
focus detecting point of the next photographing in the continuous
photographing, among a plurality of focus detecting points, in
response to movement of the photographic subject.
11. A method of image acquisition of an electronic still camera,
comprising the steps of: detecting a photographic subject based on
a captured photographic image for every photographing in continuous
photographing, when the continuous photographing is selected by a
photographer; setting the size and position of a photographic
subject area including the detected photographic subject; and
storing an image inside the photographic subject area as a
photographic subject image.
12. The method of image acquisition of the electronic still camera
according to claim 11, wherein a moving photographic subject is
detected based on a difference between a photographic image
captured at the time of previous photographing and a photographic
image captured at the time of current photographing in the
continuous photographing.
13. The method of image acquisition of the electronic still camera
according to claim 11, wherein the photographic image is divided
into plural areas, and the size and position of the photographic
subject area is set based on luminance information of the
respective areas.
14. The method of image acquisition of the electronic still camera
according to claim 11, wherein the photographic image is divided
into plural areas, and the size and position of the photographic
subject area is set based on contrast information of the respective
areas.
15. The method of image acquisition of the electronic still camera
according to claim 11, wherein the size of the photographic subject
area is set to be equal to or greater than a predetermined value
which is held in advance, irrespective of the size of a moving
photographic subject.
16. The method of image acquisition of the electronic still camera
according to claim 11, wherein the position of the photographic
subject area with respect to an image screen is stored together
with the photographic subject image.
17. The method of image acquisition of the electronic still camera
according to claim 11, wherein a predetermined area which is held
in advance is used as the photographic subject area, when a moving
photographic subject cannot be detected.
18. The method of image acquisition of the electronic still camera
according to claim 11, wherein the size of the photographic subject
area is limited in response to increase in shutter speed.
19. The method of image acquisition of the electronic still camera
according to claim 11, wherein the size of the photographic subject
area is limited in response to shortening of a photographing
interval of the continuous photographing.
20. The method of image acquisition of the electronic still camera
according to claim 11, wherein a focus detecting point of the next
photographing in the continuous photographing is decided among a
plurality of focus detecting points, in response to movement of the
photographic subject.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2004-060341, filed on
Mar. 4, 2004, the entire contents of which are incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an electronic still camera
which has a continuous photographing function for performing
successive photographing for a plurality of times in response to a
request for photographing.
[0004] 2. Description of the Related Art
[0005] Recently, data size of a photographic image is showing a
tendency to increase as the number of pixels of an electronic still
camera increases, and it is a significant challenge to usefully use
a memory area of an image storage medium for storing the
photographic image. As a technique for saving the memory area of
the image storage medium, a cropping function which cuts out a
necessary part of the photographic image simultaneously with
photographing and stores only the cut-out image in the image
storage medium is known.
[0006] In Japanese Unexamined Patent Application Publication No.
2001-236497, for example, a method of automatically performing
cropping or zooming operation around a main subject (photographic
subject) whose image is being captured, based on contents of a
photographing scene, is proposed. Further, according to a program
"XV" which is developed at University of Pennsylvania in the United
States, a cropped image is obtained by removing a uniform margin at
the boundary of the image.
[0007] However, applying the cropping function to continuous
photographing is not considered according to the conventional
electronic still camera, and hence it is impossible to change the
size of an area to be cut out (cropping area) for every
photographing in the continuous photographing. Therefore, when a
moving body is subjected to the continuous photographing, data size
of its image to be stored in the image storage medium is the same
in any photographing in the continuous photographing, although the
size of the moving body with respect to an image screen changes
over time. As a result of this, when a moving body which moves away
from a photographer is subjected to the continuous photographing,
for example, the size of the moving body with respect to the image
screen becomes smaller over time, and hence the memory area of the
image storage medium is wastefully used. Therefore, the number of
recordable photographic images at the time of continuous
photographing decreases. On the other hand, when a moving body
which moves closer to the photographer is subjected to the
continuous photographing, the size of the moving body with respect
to the image screen becomes larger over time, and hence the size of
the subject image may become larger than the set cropping area.
[0008] Moreover, according to the cropping methods of the Japanese
Unexamined Patent Application Publication No. 2001-236497 and the
program "XV", cropping of a characteristic part in the photographic
image is possible, but cropping while paying attention to the
moving photographic subject only is impossible.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide an
electronic still camera and a method of image acquisition of the
electronic still camera which can avoid wasteful usage of a memory
area of an image storing medium at the time of continuous
photographing.
[0010] According to a mode of the present invention, a photography
mode selecting section allows a photographer to select continuous
photographing. An imaging section captures an image of a subject.
An area setting section detects a photographic subject based on a
photographic image captured by the imaging section for every
photographing in the continuous photographing, and sets the size
and position of a photographic subject area including the detected
photographic subject, when the continuous photographing is selected
by the photography mode selecting section. A memory section stores
an image inside the photographic subject area as a photographic
subject image.
[0011] According to such structure, at the time of continuous
photographing of a moving body, the size of the photographic
subject area can be changed for every photographing in the
continuous photographing, according to the change in the size of
the image of the moving body with respect to an image screen of the
imaging section. Therefore, it is possible to reduce data size of
the image to be stored in the memory section to a minimum, and
avoid wasteful usage of the memory area of the memory section. In
other words, the number of images storable in the memory section at
the time of continuous photographing can be increased, and a
photographer can reduce stress caused by limitation of the storable
number at the time of photographing.
[0012] According to a preferred example of the mode of the present
invention, the area setting section detects a moving photographic
subject based on a difference between a photographic image at the
time of previous photographing and a photographic image at the time
of current photographing in the continuous photographing. By
detecting the photographic subject based on the difference between
the previous photographic image and the current photographic image,
the moving photographic subject can be detected without fail.
[0013] According to a preferred example of the mode of the present
invention, the area setting section divides the photographic image
into plural areas, and sets the size and position of the
photographic subject area based on luminance information of the
respective areas. By using the luminance information of the
photographic image, the size and position of the photographic
subject area can be easily set by software processing.
[0014] According to a preferred example of the mode of the present
invention, the area setting section divides the photographic image
into plural areas, and sets the size and position of the
photographic subject area based on contrast information of the
respective areas. By using the contrast information of the
photographic image, the size and position of the photographic
subject area can be easily set by software processing.
[0015] According to a preferred example of the mode of the present
invention, the area setting section sets the size of the
photographic subject area to be equal to or greater than a
predetermined value which is held in advance, irrespective of the
size of a moving photographic subject. By providing the
predetermined value of the size of the photographic subject area,
the photographic subject area can be set to be equal to or larger
than a fixed size, so that image quality of the photographic
subject image can be secured.
[0016] According to a preferred example of the mode of the present
invention, the memory section stores the position of the
photographic subject area with respect to an image screen of the
imaging section, together with the photographic subject image.
Thereby, the position of the photographic subject area with respect
to the image screen can be recognized easily.
[0017] According to a preferred example of the mode of the present
invention, the area setting section uses a predetermined area,
which is held in advance, as the photographic subject area, when a
moving photographic subject cannot be detected. Therefore, when the
photographic subject cannot be detected because of low-contrast of
the photographic image and the like, it is possible to prevent
focusing operation from being repeated and the continuous
photographing from being discontinued.
[0018] According to a preferred example of the mode of the present
invention, a shutter speed changing section changes shutter speed.
The area setting section limits the size of the photographic
subject area in response to increase in the shutter speed. Since
the size of the photographic subject area is limited in response to
the increase in the shutter speed, it is possible to increase the
number of images storable in the memory section, when the number of
images obtained per unit of time increases as the shutter speed
increases.
[0019] According to a preferred example of the mode of the present
invention, a continuous photographing speed changing section
changes a photographing interval of the continuous photographing.
The area setting section limits the size of the photographic
subject area in response to shortening of the photographing
interval of the continuous photographing. Since the size of the
photographic subject area is limited in response to the shortening
of the photographing interval of the continuous photographing, it
is possible to increase the number of images storable in the memory
section, when the number of images obtained per unit of time
increases as the photographing interval is shortened.
[0020] According to a preferred example of the mode of the present
invention, a focus detecting point decision section decides a focus
detecting point of the next photographing in the continuous
photographing, among a plurality of focus detecting points, in
response to movement of the photographic subject.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The nature, principle, and utility of the invention will
become more apparent from the following detailed description when
read in conjunction with the accompanying drawings in which like
parts are designated by identical reference numbers, in which:
[0022] FIG. 1 is a block diagram showing a first embodiment of an
electronic still camera of the present invention;
[0023] FIG. 2 is a flow chart showing photographing operation of
the electronic still camera according to the first embodiment;
[0024] FIG. 3 is a flow chart showing the photographing operation
of the electronic still camera according to the first
embodiment;
[0025] FIGS. 4(a) to 4(c) are explanatory views showing an example
of a setting method of a photographic subject area at the time of
continuous photographing;
[0026] FIG. 5 is a block diagram showing a second embodiment of the
electronic still camera of the present invention;
[0027] FIG. 6 is a flow chart showing photographing operation of
the electronic still camera according to the second embodiment;
[0028] FIG. 7 is a flow chart showing the photographing operation
of the electronic still camera according to the second
embodiment;
[0029] FIG. 8 is a block diagram showing a third embodiment of the
electronic still camera of the present invention; and
[0030] FIG. 9 is a flow chart showing photographing operation of
the electronic still camera according to the third embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Hereinafter, preferred embodiments of the present invention
will be explained with reference to the drawings.
[0032] FIG. 1 shows a first embodiment of an electronic still
camera of the present invention.
[0033] An electronic still camera 10 is a digital single lens
reflex camera, and is constituted of a main unit 12 and a lens unit
14 which is attached to a front surface of a casing of the main
unit 12.
[0034] The main unit 12 includes a microcontroller 16 for
controlling the electronic still camera 10 as a whole. In the main
unit 12, a quick return mirror 18, a mechanical shutter 19, and a
light-receiving surface of an imaging device 20 (CMOS sensor) for
capturing an image of a subject are disposed on an optical axis of
the lens unit 14. In a reflecting direction of the mirror 18 (upper
side in the drawing), a finder optical system 22 is disposed. In a
reflecting direction of a submirror of the mirror 18 (lower side in
the drawing), a focus detecting unit 24 for detecting a focusing
state of the subject image is disposed. Focus detecting data which
is outputted from the focus detecting unit 24 is supplied to the
microcontroller 16.
[0035] Image data outputted from the imaging device 20 (imaging
section) is subjected to color signal processing, A/D conversion,
gamma correction and so on by an image processing unit 26, and
thereafter recorded in an image memory 28. Image data outputted
from the image memory 28 is supplied to an image compressing unit
30. The image compressing unit 30 is connected to the
microcontroller 16. Further, a memory card 34 (memory section) for
recording images, photographing conditions and the like is
detachably connected to the microcontroller 16 via a card interface
32.
[0036] A CMOS drive circuit 36 for driving the imaging device 20,
an optical measurement unit 38 for performing optical measurement
of luminance of the subject image, and an image display circuit 40
for controlling display of the image data recorded in the image
memory 28 are connected to the microcontroller 16. Image data
outputted from the image display circuit 40 is supplied to a
display unit 42 (liquid crystal panel) for monitoring, which is
disposed on a back surface of the casing of the main unit 12.
Moreover, a photographic subject area decision circuit 44 (area
setting section) for setting the size and position of a
photographic subject area including a photographic subject at the
time of continuous photographing, and an area position calculating
circuit 46 for calculating the position of the photographic subject
area with respect to an image screen of the imaging device 20 are
connected to the microcontroller 16.
[0037] An operation unit 48 for setting the photographing
conditions and the like, and a release button 56 for requesting
photographing are provided on the casing of the main unit 12. The
operation unit 48 includes a photography mode change-over switch 50
(photography mode selecting section) for allowing a photographer to
select the continuous photographing. It should be noted that,
although not illustrated, the operation unit 48 also includes a
power switch, a rotary dial selection switch for selecting an
exposure method according to a photographing scene, an image
recording setting switch for setting image recording conditions at
the time of photographing, a liquid crystal information display
unit for displaying setting information, and so on. Outputs from
the operation unit 48 and the release button 56 are respectively
supplied to the microcontroller 16.
[0038] The lens unit 14 is constituted of a plurality of single
lenses, and includes a focusing lens 58 which moves so that the
subject image is focused on the imaging device 20, an iris 60 which
is placed at a predetermined position between the lenses and is
constituted of a plurality of panels for adjusting light intensity,
a lens and iris diaphragm drive mechanism 62 which drives the
focusing lens 58 and the iris 60 according to instructions from the
microcontroller 16, and an encoder 64 which detects the position of
the focusing lens 58. Incidentally, besides the focusing lens 58,
the lens unit 14 also includes a not-shown zoom lens which moves
for applying a zoom function, and the zoom lens is driven by
instructions from a not-shown operation member via the lens and
iris diaphragm drive mechanism 62.
[0039] Next, a photographing sequence of the electronic still
camera 10 according to the first embodiment will be explained.
[0040] A photographer installs the memory card 34 and turns on the
power switch of the operation unit 48. Then, the photographer
operates the mode change-over switch 50 of the operation unit 48 to
select the continuous photographing, and operates the operation
unit 48 to set various photographing conditions such as image
quality, recording size, white balance, sensitivity, AF area, and
exposure. Further, the photographer sets the direction of the
electronic still camera 10 so that a point to be focused on of the
subject is in agreement with a focus detecting point at the center
of an image screen.
[0041] FIG. 2 and FIG. 3 show photographing operation of the
electronic still camera 10 according to the first embodiment.
[0042] In a step S110, the microcontroller 16 determines whether
the release button 56 is in a half-pressed state or not. When the
release button 56 is in the half-pressed state, processing proceeds
to a step S120. When the release button 56 is not in the
half-pressed state, determining operation by the microcontroller 16
is repeated.
[0043] In the step S120, the microcontroller 16 obtains the optical
measurement result of luminance of the subject image by the optical
measurement unit 38 (subject luminance data). Thereafter,
processing proceeds to a step S130.
[0044] In the step S130, the microcontroller 16 obtains the focus
detecting result by the focus detecting unit 24 (focus detecting
data). Thereafter, processing proceeds to a step S140.
[0045] In the step S140, the microcontroller 16 instructs the lens
and iris diaphragm drive mechanism 62 to adjust the lens based on
the focus detecting data obtained in the step S130. The lens and
iris diaphragm drive mechanism 62 follows the instruction from the
microcontroller 16 to drive the focusing lens 58. Thereafter,
processing proceeds to a step S150.
[0046] In the step S150, the microcontroller 16 determines whether
focus is achieved or not. When the focus is achieved, processing
proceeds to a step S160. When the focus is not achieved, processing
returns to the step S130. Namely, the steps S130 to S150 are
repeatedly performed until the focus is achieved.
[0047] In the step S160, the microcontroller 16 determines whether
the release button 56 is in a fully-pressed state or not. When the
release button 56 is in the fully-pressed state, processing
proceeds to a step S170. When the release button 56 is not in the
fully-pressed state, processing returns to the step S110.
[0048] In the step S170, the microcontroller 16 instructs the lens
and iris diaphragm drive mechanism 62 to adjust the iris based on
the subject luminance data obtained in the step S120. The lens and
iris diaphragm drive mechanism 62 follows the instruction from the
microcontroller 16 to drive the iris 60. Thereafter, processing
proceeds to a step S180.
[0049] In the step S180, the microcontroller 16 flips the mirror 18
upward (upper side in the drawing). Thereafter, processing proceeds
to a step S190.
[0050] In the step S190, the microcontroller 16 opens the
mechanical shutter 19 disposed opposingly to the imaging device 20.
Thereby, charge storage of the imaging device 20 is started, and a
full photographic image (image of an entire image screen) is
recorded in the image memory 28 via the image processing unit 26.
Thereafter, processing proceeds to a step S200.
[0051] In the step S200, the microcontroller 16 determines whether
the continuous photographing is selected or not. When the
continuous photographing is selected, processing proceeds to a step
S210. When the continuous photographing is not selected (that is,
when single photographing is selected), processing proceeds to a
step S260.
[0052] In the step S210, the microcontroller 16 detects a moving
photographic subject by using a difference between the previous
full photographic image and the current full photographic image in
the continuous photographing, to thereby find a motion vector of
the photographic subject. Namely, the microcontroller 16
automatically tracks the photographic subject. According to the
detected photographic subject, the microcontroller 16 decides the
position of a non-delete area which gives a lower limit of the size
of the photographic subject area. Incidentally, at the time of
first photographing in the continuous photographing, the position
which is set in advance (center of the photographic image, for
example) is used as the position of the non-delete area. At this
time, the focus detecting point moves to the focus detecting point
which is close to the point to be focused on of the moved subject,
accompanying the movement of the photographic subject. Thereafter,
processing proceeds to a step S220.
[0053] In the step S220, the microcontroller 16 instructs the
photographic subject area decision circuit 44 to set the
photographic subject area. The photographic subject area decision
circuit 44 divides the full photographic image into plural areas,
and sets the photographic subject area based on luminance
information of the respective areas. The setting method of the
photographic subject area will be explained in detail with
reference to FIGS. 4(a) to 4(c). Thereafter, processing proceeds to
a step S230.
[0054] In the step S230, the microcontroller 16 obtains the
position of the photographic subject area with respect to the image
screen of the imaging device 20 (position coordinates of the left
upper corner, for example) from the area position calculating
circuit 46. Thereafter, processing proceeds to a step S240.
[0055] In the step S240, in the case of continuous photographing,
the microcontroller 16 adds the position of the photographic
subject area with respect to the image screen, which is obtained in
the step S230, as tag information, to the photographic subject
image (image inside the photographic subject area set in the step
S220) in Exif (Exchangeable Image File Format) format, and records
it to the memory card 34 via the card interface 32. Thereafter,
processing proceeds to a step S250.
[0056] In the step S250, the microcontroller 16 determines whether
the release button 56 is in a fully-pressed state or not. When the
release button 56 is in the fully-pressed state, processing returns
to the step S120 and new photographing in the continuous
photographing is performed. When the release button 56 is not in
the fully-pressed state, the continuous photographing is completed.
In other words, the continuous photographing continues as long as
the release button 56 is in the fully-pressed state.
[0057] In the step S260, in the case of the single photographing,
the microcontroller 16 records the full photographic image in the
Exif format to the memory card 34 via the card interface 32.
Thereby, the single photographing is completed.
[0058] FIGS. 4(a) to 4(c) show an example of the setting method of
the photographic subject area at the time of continuous
photographing.
[0059] The case where the full photographic image as shown in FIG.
4(a) is obtained when the continuous photographing of a moving car
is performed will be explained as an example.
[0060] As shown in FIG. 4(b), the photographic subject area
decision circuit 44 divides the area of the photographic image
shown in FIG. 4(a) into an 8.times.8 matrix, and excludes
unnecessary areas from the photographic subject area based on the
luminance information of the respective areas, to thereby decide
the size and position of the photographic subject area.
Incidentally, it is supposed that the non-delete area set in the
step S210 in FIG. 3 (for example, a rectangular area constituted of
the areas A(3,3) to A(6,6) shown in the bold line in FIG. 4(b)) is
not excluded from the photographic subject area.
[0061] First, the photographic subject area decision circuit 44
calculates average luminance values L(1,1) to L(8,8) of the
respective areas A(1,1) to A(8,8), respectively. The average
luminance value of the area can be found from the result of
integration of a graph obtained by assuming a horizontal axis to be
the luminance from 0 to 255 (8-bit gradation), and a vertical axis
to be the number of pixels (frequency). Incidentally, the area
which is in the m-th column from the left and the n-th row from the
top in the drawing is represented as A(m,n), and the average
luminance value of the area A(m,n) is represented as L(m,n).
[0062] Next, the photographic subject area decision circuit 44 uses
the following expression (1) to find an average value LY(n) of the
average luminance values L(1,n) to L(8,n) of the areas in the n-th
column A(1,n) to A(8,n).
LY(n)={L(1,n)+L(2,n)+ . . . +L(7,n)+L(8,n)}/8 (1)
[0063] Then, the photographic subject area decision circuit 44 uses
the following expression (2) to find an absolute value
.vertline..DELTA.LY(m,n).vertline. of a difference between the
average value LY(n) and the average luminance values L(1,n) to
L(8,n).
.vertline..DELTA.LY(m,n).vertline.=LY(n)-L(m,n), m=1,2, . . . ,7,8
(2)
[0064] Thereafter, when all of .vertline..DELTA.LY(1,n).vertline.
to .vertline..DELTA.LY(8,n).vertline. are equal to or smaller than
30, for example, the photographic subject area decision circuit 44
excludes the areas in the n-th row A(1,n) to A(8,n) from the
photographic subject area. More specifically, the photographic
subject area decision circuit 44 does not exclude the areas in the
n-th row A(1,n) to A(8,n) from the photographic subject area when
at least one of .vertline..DELTA.LY(1,n).v- ertline. to
.vertline..DELTA.LY(8,n).vertline. is greater than 30. In FIG.
4(b), for example, the areas in the first row A(1,1) to A(8,1), the
areas in the seventh row A(1,7) to A(8,7) and the areas in the
eighth row A(1,8) to A(8,8) are excluded from the photographic
subject area.
[0065] Next, the photographic subject area decision circuit 44 uses
the following expression (3) to find an average value LX(m) of the
average luminance values L(m,2) to L(m,6) of the areas A(m,2) to
A(m,6), which are the areas in the m-th column A(m,1) to A(m,8)
except for the already-excluded areas A(m,1), A(m,7) and
A(m,8).
LX(m)={L(m,2)+L(m,3)+L(m,4)+L(m,5)+L(m,6)}/5 (3)
[0066] Then, the photographic subject area decision circuit 44 uses
the following expression (4) to find an absolute value
.vertline..DELTA.LX(m,n).vertline. of a difference between the
average value LX(m) and the average luminance values L(m,2) to
L(m,6).
.vertline..DELTA.LX(m,n).vertline.=LX(m)-L(m,n), n=2,3,4,5,6
(4)
[0067] Thereafter, when all of .vertline..DELTA.LX(m,2).vertline.
to .vertline..DELTA.LX(m,6).vertline. are equal to or smaller than
30, for example, the photographic subject area decision circuit 44
excludes the areas in the m-th column A(m,2) to A(m,6) from the
photographic subject area. More specifically, the photographic
subject area decision circuit 44 does not exclude the areas in the
m-th column A(m,2) to A(m,6) from the photographic subject area
when at least one of .vertline..DELTA.LX(m,2).vertline. to
.vertline..DELTA.LX(m,6).vertline. is greater than 30. In FIG.
4(b), the areas in the first column A(1,2) to A(1,6), and the areas
in the eighth column A(8,2) to A(8,6) are excluded from the
photographic subject area.
[0068] Thus, the photographic subject area decision circuit 44
decides the size and position of the photographic subject area (the
part not being filled in with black in the drawing) including the
photographic subject (moving car) as shown in FIG. 4(c).
Incidentally, the photographic subject area may be set using
contrast information of the respective areas, instead of the
luminance information of the respective areas. Moreover, a slice
level for area exclusion (30 in the above example) may be set
arbitrarily, or the slice level may be set for each area according
to shading characteristics by an imaging optical system or the
like. Furthermore, the areas in the n-th row (or in the m-th
column) may be excluded from the photographic subject area when the
number of areas whose .vertline..DELTA.LY(m,n).vertline. (or
.vertline..DELTA.LX(m,n).ver- tline.) is equal to or smaller than
the slice level in the n-th row (or in m-th column) is equal to or
greater than a predetermined number.
[0069] The following effects can be obtained according to the
above-described first embodiment.
[0070] At the time of continuous photographing of a moving body,
the size of the photographic subject area can be changed for every
photographing of the continuous photographing, according to the
change in the size of the image of the moving body with respect to
the image screen of the imaging device 20. Therefore, it is
possible to reduce data size of the image to be recorded in the
memory card 34 to a minimum, and avoid wasteful usage of a memory
area of the memory card 34. In other words, it is possible to
increase the number of images recordable in the memory card 34 at
the time of continuous photographing. Further, since zoom
processing of the moving photographic subject can be performed
without operating the lens unit 14 or the operation unit 48 of the
electronic still camera 10, it is possible to reduce the
possibility that camera shake is caused.
[0071] Since the luminance information of the photographic image is
used, it is possible to easily set the size and position of the
photographic subject area by software processing.
[0072] By providing the non-delete area which gives the lower limit
of the size of the photographic subject area, the size of the
photographic subject area can be set to be equal to or larger than
a fixed size even when the size of the image of the moving body is
small, so that the image quality of the photographic subject area
can be secured.
[0073] FIG. 5 shows a second embodiment of the electronic still
camera of the present invention. Incidentally, the same numerals
and symbols are given to designate the same elements as those
explained in the first embodiment, and detailed explanations
thereof will be omitted.
[0074] An electronic still camera 10a includes an operation unit
48a instead of the operation unit 48 (FIG. 1) in the first
embodiment. The operation unit 48a is constituted by adding a
shutter speed change-over switch 52 (shutter speed changing
section), which sets the shutter speed at either "high speed" or
"standard speed", to the operation unit 48 in the first embodiment.
The rest of the structure of the electronic still camera 10a is the
same as that of the electronic still camera 10 (FIG. 1) in the
first embodiment.
[0075] FIG. 6 and FIG. 7 show photographing operation of the
electronic still camera 10a according to the second embodiment.
[0076] Similarly to the first embodiment (FIG. 2), steps S110 to
S140 are performed according to operation by a photographer.
[0077] In a step S152, a microcontroller 16 sets a flag FC at "1"
when it is determined that focus is achieved in a step S150.
Thereafter, processing proceeds to a step S160.
[0078] In a step S154, the microcontroller 16 resets the flag FC to
"0" when it is determined that the focus is not achieved in the
step S150. Thereafter, processing proceeds to the step S160.
[0079] Then, similarly to the first embodiment (FIG. 2 and FIG. 3),
steps S160 to S200 are performed according to operation by the
photographer.
[0080] In a step S202, the microcontroller 16 determines whether
the flag FC is "1" or not. When the flag FC is "1", processing
proceeds to a step S210. In the step S210, the same processing as
that in the step S210 in the first embodiment is performed. When
the flag FC is "0", processing proceeds to a step S242.
[0081] In a step S212 (after performing the step S210), the
microcontroller 16 determines whether the shutter speed is set at
the "standard speed" or not. When the shutter speed is set at the
"standard speed", processing proceeds to a step S220, where a
photographic subject area is set by the same method as that in the
first embodiment. When the shutter speed is not set at the
"standard speed" (when the shutter speed is set at the "high
speed"), processing proceeds to a step S222.
[0082] In the step S222, when the shutter speed is set at the "high
speed", the microcontroller 16 uses a non-delete area which is set
in the step S210 as the photographic subject area, and limits the
size of the photographic subject area. Thereafter, processing in
and after a step S230 are performed according to operation by the
photographer, similarly to the first embodiment.
[0083] In the step S242, when the flag FC is "0", the
microcontroller 16 records a full photographic image as a
photographic subject image to a memory card 34 via a card interface
32 in Exif format. In other words, when a photographic subject
cannot be detected, the microcontroller 16 uses an entire image
screen as the photographic subject area. Thereafter, processing in
and after a step S250 are performed similarly to the first
embodiment.
[0084] The same effects as those of the first embodiment can be
obtained according to the above-described second embodiment as
well. Further, when the focus is not achieved, that is, when the
photographic subject cannot be detected, it is possible to prevent
focusing operation from being repeated by regarding the entire
image screen as the photographic subject area. As a result of this,
at the time of continuous photographing, photographing by a
predetermined number of times within a predetermined time can be
performed without fail.
[0085] When the shutter speed is set at the "high speed" by the
photographer, the non-delete area is set as the photographic
subject area, so that the number of images storable in the memory
card 34 at the time of continuous photographing can be
increased.
[0086] FIG. 8 shows a third embodiment of the electronic still
camera of the present invention. Incidentally, the same numerals
and symbols are given to designate the same elements as those
explained in the first embodiment, and detailed explanations
thereof will be omitted.
[0087] An electronic still camera 10b includes an operation unit
48b instead of the operation unit 48 (FIG. 1) in the first
embodiment. The operation unit 48b is constituted by adding a
continuous photographing speed change-over switch 54 (continuous
photographing speed changing section), which sets a photographing
interval of the continuous photographing (continuous photographing
speed) at either "high speed" or "standard speed", to the operation
unit 48 in the first embodiment. The rest of the structure of the
electronic still camera 10b is the same as that of the electronic
still camera 10 (FIG. 1) in the first embodiment.
[0088] FIG. 9 shows operation of the electronic still camera 10b
according to the third embodiment. Incidentally, processing in
steps S110 to S190 in the third embodiment are the same as those in
the first embodiment (FIG. 2), and hence illustration thereof will
be omitted.
[0089] First, similarly to the first embodiment (FIG. 2 and FIG.
3), steps S110 to S210 are performed according to operation by a
photographer.
[0090] In a step S214 (after performing the step S210), a
microcontroller 16 determines whether the continuous photographing
speed (photographing interval of the continuous photographing) is
set at the "standard speed" or not. When the continuous
photographing speed is set at the "standard speed", processing
proceeds to a step S220, where a photographic subject area is set
by the same method as that in the first embodiment. When the
continuous photographing speed is not set at the "standard speed"
(when the continuous photographing speed is set at the "high
speed"), processing proceeds to a step S224.
[0091] In the step S224, when the continuous photographing speed is
set at the "high speed", the microcontroller 16 uses a non-delete
area which is set in the step S210 as the photographic subject
area, and limits the size of the photographic subject area.
Thereafter, processing in and after a step S230 are performed
according to operation by the photographer, similarly to the first
embodiment.
[0092] The same effects as those of the first embodiment can be
obtained according to the above-described third embodiment as well.
Further, when the photographing interval of the continuous
photographing is shortened by the photographer, the non-delete area
is set as the photographic subject area, so that the number of
images storable in a memory card 34 at the time of continuous
photographing can be increased.
[0093] Incidentally, according to the first to third embodiments,
the example of applying the present invention to the digital single
lens reflex camera is explained. The present invention is not
limited to such embodiments. For example, the present invention may
be applied to the so-called digital compact camera which displays
an image of a subject before photographing on an LCD (Liquid
Crystal Display).
[0094] According to the first to third embodiments, the example of
applying the present invention to the electronic still camera is
explained. The present invention is not limited to such
embodiments. For example, the present invention may be applied to a
digital camera function of portable equipment such as a cellular
phone and a PDA (Personal Digital Assistant).
[0095] According to the first to third embodiments, the example of
employing the CMOS sensor as the imaging device is explained. The
present invention is not limited to such embodiments. For example,
a CCD (Charge Coupled Device) sensor may be used as the imaging
device, or a random-access imaging device other than the CMOS
sensor, which can select any XY address, may be employed.
[0096] According to the first to third embodiments, the example in
which the mechanical shutter 19 is disposed between the lens unit
14 and the imaging device 20 is explained. The present invention is
not limited to such embodiments. For example, when the imaging
device 20 has an electronic shutter function, the mechanical
shutter 19 may be omitted. In other words, the mechanical shutter
19 is necessary when the imaging device 20 does not have the
electronic shutter function.
[0097] According to the first to third embodiments, the example of
providing the non-delete area which gives the lower limit of the
size of the photographic subject area is explained. The present
invention is not limited to such embodiments. For example, when it
is unnecessary to set the size of the photographic subject area to
be equal to or larger than a fixed size, the same effects can be
obtained even if the non-delete area is not provided thereto.
[0098] The invention is not limited to the above embodiments and
various modifications may be made without departing from the spirit
and scope of the invention. Any improvement may be made in part or
all of the components.
* * * * *