U.S. patent application number 13/570047 was filed with the patent office on 2012-12-06 for lighting control module, video camera comprising the same and control method of the same.
Invention is credited to Jen-Hui CHUANG, Pang-Chan Hung, Kuo-Hua Lo.
Application Number | 20120307137 13/570047 |
Document ID | / |
Family ID | 43925056 |
Filed Date | 2012-12-06 |
United States Patent
Application |
20120307137 |
Kind Code |
A1 |
CHUANG; Jen-Hui ; et
al. |
December 6, 2012 |
LIGHTING CONTROL MODULE, VIDEO CAMERA COMPRISING THE SAME AND
CONTROL METHOD OF THE SAME
Abstract
The present invention provides a lighting control module, a
video camera comprising the same and a control method of the same.
The video camera of the invention includes a sensing module, a
light-emitting module and a control module. The sensing module
receives a reflected light beam from a recording direction of the
video camera, and generates an image of a scene in the recording
direction. The light-emitting module emits a light toward the
recording direction. Additionally, the lighting control module is
connected to the light-emitting module for controlling the
light-emitting module to periodically emit the light from a first
brightness to a second brightness.
Inventors: |
CHUANG; Jen-Hui; (Hsinchu
City, TW) ; Lo; Kuo-Hua; (Kaohsiung City, TW)
; Hung; Pang-Chan; (Sanchong City, TW) |
Family ID: |
43925056 |
Appl. No.: |
13/570047 |
Filed: |
August 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12786179 |
May 24, 2010 |
8253849 |
|
|
13570047 |
|
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Current U.S.
Class: |
348/371 ;
348/E5.029 |
Current CPC
Class: |
G03B 42/00 20130101;
G03B 15/03 20130101; H04N 5/2354 20130101 |
Class at
Publication: |
348/371 ;
348/E05.029 |
International
Class: |
H04N 5/225 20060101
H04N005/225 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2009 |
TW |
098136917 |
Claims
1. A lighting control module, connected to at least a light
emitting module, for controlling the light emitting module to emit
a light toward a recording direction of a camera, wherein the
lighting control module controls the light emitted by the light
emitting module to change periodically from a first brightness to a
second brightness.
2. The lighting control module of claim 1, wherein the camera
further comprises: a sensing module, for receiving a reflected
light from the recording direction and generating an image related
to the recording direction; and a processing module, connected to
the sensing module, for calculating an environmental brightness in
the recording direction according to the image and generating a
brightness information, wherein the lighting control module is
connected to the processing module to receive the brightness
information and adjust the range of the first brightness and the
second brightness according to the brightness information.
3. The lighting control module of claim 2, wherein the reflected
light is a near infrared.
4. The lighting control module of claim 1, wherein the light
emitting module comprises a strength of the light emitted by the
light emitting module, so that the light emitted by the light
emitting module changes periodically from the first brightness to
the second brightness.
5. The lighting control module of claim 1, wherein the light
emitting module is integrated within the camera or is independent
from the camera.
6. The lighting control module of claim 1, wherein the lighting
control module controls the light emitted by the light emitting
module to change periodically and continuously from the first
brightness to the second brightness.
7. The lighting control module of claim 1, wherein the lighting
control module controls the light emitted by the light emitting
module to change periodically from the first brightness to the
second brightness and then back to the first brightness.
8. The lighting control module of claim 1, wherein the lighting
control module controls the light emitted by the light emitting
module to change periodically from the first brightness to the
second brightness within a light emitting period, and an entire
length of the light emitting period is proportional to a total
number of light emitting diodes in the lighting control module.
9. A camera, comprising: a sensing module for receiving a reflected
light emitted from a recording direction of the camera and
generating an image in the recording direction; a light emitting
module for emitting a light toward the recording direction; and a
lighting control module, connected to the light emitting module,
for controlling the light emitted by the light emitting module to
change periodically from a first brightness to a second
brightness.
10. The camera of claim 9, further comprising: a processing module,
connected to the sensing module for, based on the image,
calculating an environmental brightness on the recording direction,
and generating a brightness information; wherein the lighting
control module is connected to the processing module to receive the
brightness information and adjust the range of the first brightness
and the second brightness according to the brightness
information.
11. The camera of claim 9, wherein the reflected light is a near
infrared.
12. The camera of claim 9, wherein the lighting control module
controls the strength of the light emitted by the light emitting
module, so that the light emitted by the light emitting module
changes periodically from the first brightness to the second
brightness.
13. The camera of claim 9, wherein the lighting control module
controls the light emitted by the light emitting module to change
periodically and continuously from the first brightness to the
second brightness.
14. The camera of claim 9, wherein the lighting control module
controls the light emitted by the light emitting module to change
periodically from the first brightness to the second brightness and
then back to the first brightness.
15. The camera of claim 9, wherein the lighting control module
controls the light emitted by the light emitting module to change
periodically from the first brightness to the second brightness
within a light emitting period, and an entire length of the light
emitting period is proportional to a total number of light emitting
diodes in the lighting control module.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of co-pending application
Ser. No. 12/786,179 filed on May 24, 2010, which claims priority to
Application No. 098136917 filed in Taiwan, on Oct. 30, 2009. The
entire contents of all of the above applications are hereby
incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a lighting control module,
a video camera comprising the same and a lighting control method,
and more particularly, to an infrared surveillance camera and a
control method of the same.
BACKGROUND OF THE INVENTION
[0003] As the camera related technology (For example, the sensing
technology of the sensing device and the image processing
technology of processing device, etc.) moves forwards, the camera
nowadays can, under all kinds of environments (For example, indoor,
within a vehicle, in the night time, or in the rainy day, etc.),
perform image acquisition and processing so as to provide the
needed image information to the user.
[0004] Among many camera applications, video surveillance is one
area that seizes attention in recent years, and its application
scope as well as importance grows with time too. For example, the
surveillance camera installed on the roadside can be provided to
the traffic authority to seize the traffic condition at any time
and to perform the traffic sign change or to increase the traffic
guidance flexibility. The surveillance camera installed at home can
let the residents seize the real time situation of their homes,
especially when there is a long way travel, or there is elderly
people, weak people, woman or children, that is, the residents can
go for a long travel with peace of mind. In addition, the
installation of the surveillance camera in the alley or the
peripheral of a building can let the police or the guard seize the
public security condition, especially when there is crime involved,
the police can check out the video to watch its content so as to
seize the condition at the crime scene and the features of the
suspect.
[0005] Since crime usually occurs in the night, and the crime scene
is usually at the dead space or dark corner in the community which
no body pays attention to, hence, the near infrared camera that has
night photography function has become necessity for video
surveillance. The wavelength of the near infrared is about in the
range 700 to 4,000 nm. Through the sensing of image in the near
infrared wavelength range, the near infrared camera can generate
clearer image in the night or in the dark place.
[0006] However, the image captured with a near infrared camera
usually has the issues of insufficient contrast, insufficiently
sharp features of foreground object, hence, the expected subject
image is usually not clear, and its features are thus difficult to
be recognized.
SUMMARY OF THE INVENTION
[0007] One objective of the present invention is to provide one
lighting control module to solve the above prior art issues.
[0008] Based on one embodiment, the lighting control module is
connected to at least a light emitting module and is used to
control the light emitting module to emit one optical beam toward
the recording direction of the camera, and the features are: the
lighting control module will control the light emitted from the
light emitting module to change periodically from a first
brightness to a second brightness. In other words, the lighting
control module of the present invention can be simultaneously
connected to multiple light emitting modules and control
respectively the optical beams from those light emitting module to
change periodically from the first brightness to the second
brightness.
[0009] What needs to be noticed is, the above mentioned light
emitting module can be integrated into camera or can be independent
from the camera.
[0010] Another objective of the present invention is to provide a
camera to solve the prior art issue.
[0011] Based on one embodiment, the camera contains one sensing
module, one light emitting module and the above mentioned lighting
control module. The sensing module can receive a reflected light
from one recording direction of the camera and generate an image on
the recording direction. The light emitting module emits a light in
the recording direction. In addition, the lighting control module
is connected to the light emitting module so as to control the
light emitted from the light emitting module to change periodically
from a first brightness to a second brightness.
[0012] Yet another objective of the present invention is to provide
a lighting control method to solve the prior art issue.
[0013] Based on one embodiment, the lighting control method can
control at least a light emitting module of a camera to emit a
light beam toward a recording direction of the camera, and the
features are: the lighting control method control the light emitted
from the light emitting module to change periodically from a first
brightness to a second brightness.
[0014] To sum up the above, the lighting control module based on
the present invention comprising of a camera of the lighting
control module and a lighting control method to control
periodically the light emitting module of the camera to emit light
from strong to weak intensity or from weak to strong intensity,
hence, the camera, within a light emitting period, can acquire
clear images of objects of different depths of focus.
[0015] The advantages and spirit regarding the present invention
can be further understood through the following detailed
descriptions and drawings of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates the functional block diagram of one
embodiment of the camera based on the present invention.
[0017] FIG. 2 illustrates, based on one embodiment of the present
invention, how the lighting control module controls the light
emitting module of the camera.
[0018] FIGS. 3A to 3C illustrate respectively the temporal
relationship between the light emitting period and LED light
emitting quantity of the present invention.
[0019] FIG. 4 illustrates, based on one embodiment of the present
invention, the block diagram for the control method of the
camera.
[0020] FIGS. 5A to 5G illustrates the recording results based on
the brightness scanning of the camera of the present invention with
a distance between foreground object to the camera of about 1.5
meters.
[0021] FIGS. 6A to 6F illustrates the recording results based on
the brightness scanning of the camera of the present invention with
a distance between foreground object to the camera of about 3
meters.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention provides a lighting control module,
comprising of a camera of the lighting control module and a
lighting control method. In the followings, the embodiments and
real applications of the present invention are going to be
explained in detail so as to fully explain the features, spirit and
advantages of the present invention.
[0023] FIG. 1 illustrates the functional block diagram based on one
embodiment of the present invention. As shown in the figure, the
camera 1 of the present invention comprising of the sensing module
10, the processing module 12, the light emitting module 14 and the
lighting control module 16.
[0024] The sensing module 10 includes the Charge-Coupled Device
(CCD), Complementary Metal-Oxide-Semiconductor (CMOS) or other
appropriate sensing device so as to receive a reflected light on
the recording direction F aligned by the camera 1 and to generate
an image on the recording direction F. In addition, practically,
the front side of the sensing module can be installed with lens
module to focus the light beam onto the sensing device to form the
image. Meanwhile, practically, the reflected light is of near
infrared.
[0025] The processing module 12, for example, but is not limited to
the microprocessor, is connected to the sensing module 10 to
process the image generated by the sensing module 10, meanwhile,
based on this image, the environmental brightness in the recording
direction F is calculated, and the brightness information is then
generated based on this information.
[0026] The light emitting module 14 can emit light in the above
camera direction F. In the present embodiment, the light emitting
module 14 is made up of a plurality of the light emitting diodes
140, and those light emitting diodes 140 can be installed by
surrounding the above mentioned lens module. Of course,
practically, the light emitting module 14 can be made up of other
proper optical sources. In addition, in the present embodiment,
light emitted by the light emitting module 14 is near infrared.
[0027] The lighting control module 16, for example, but not limited
to the microprocessor, is connected to the light emitting module 14
to control the light emitted from the light emitting module 14 to
change periodically from a first brightness to a second brightness.
Practically, the first brightness and the second brightness can be
respectively the maximum and minimum brightness that the light
emitting module 14 can generate, and vice versa. In other words,
the lighting control module 16 of the present invention can control
the light emitted brightness of the light emitting module 14,
within a light emitting period, to change gradually from maximum to
minimum, or gradually from minimum to maximum, and the circulation
is repeated continuously.
[0028] For example, if the maximum light emitting brightness of the
light emitting module 14 is of 100 units, and the minimum light
emitting brightness is of 10 units. The lighting control module 16
can control the light emitting module 14, within a light emitting
period, to start sending 100 units of light and to weaken gradually
down to 10 units of light to complete a light emitting period, then
it will start again from 100 units of light for another light
emitting period. Or, the lighting control module might control the
first light emitting module 14 to send out 10 units of light, and
gradually increase the light to 100 units to complete a light
emitting period, then it will start again from 100 units of light
for another light emitting period.
[0029] Moreover, the lighting control module will control the first
light emitting module 14 to emit light of 10 units and increase it
gradually to 100 units, then decrease it gradually again to 10
units to complete a light emitting period, then another light
emitting period is started from light of 100 units. Of course,
practically, the light intensity change in each light emitting
period can be decided by the designer and is not limited to the
embodiment as made in this patent specification.
[0030] In addition, the lighting control module 16 can also be
connected to the processing module 12 so as to receive
environmental brightness information from the processing module 12,
meanwhile, based on the brightness information, the scope of the
above mentioned first brightness and second brightness is adjusted.
What needs to be noticed is, during the actual application, the
lighting control module 16 and the processing module 12 can be
integrated into a single chip.
[0031] Take the above case as an example, when the environmental
brightness is insufficient, the scope of the first brightness and
second brightness can be in between 50 units and 100 units;
meanwhile, when the environmental brightness is sufficient, the
scope of first brightness and second brightness can be in between
10 units and 50 units. In other words, when environmental
brightness is considered, the light emitting module 14 of the
present invention can complete a light emitting period more quickly
so as to increase the circulation frequency of the light emitting
period.
[0032] In the actual application, the lighting control module 16 of
the present invention the light emitting brightness of light
emitting module 14 is controlled through the control of the light
emitting quantity of the light emitting diodes 140 in the light
emitting module 14. In other words, the lighting control module 16
will follow light emitting diode quantity to decide the light
emitting period so as to control the light, within the light
emitting period, to change from the first brightness to the second
brightness.
[0033] For example, suppose the image acquisition frequency of the
camera 1 is 30 fps, the unit length (T) of light emitting period
will be larger than or equal to the quantity of light emitting
diode (LEDMax) divided by 30 (seconds), which is as shown in the
following [equation 1]. Briefly speaking, according to [equation
1], when the quantity of LED is 45, each light emitting period will
be 15 seconds; when LED quantity is 24, each light emitting period
will be 0.8 seconds.
T.gtoreq.LED.sub.Max/30.sub.(seconds) [Equation 1]
[0034] Of course, practically, the unit length of light emitting
period can be adjusted based on actual need and is not limited to
the above embodiments.
[0035] Please refer again to FIG. 2, which shows, based on one
embodiment of the present invention, how the lighting control
module controls the light emitting module of the camera. As shown
in the figure, the lighting control module 16 of the present
invention can be simultaneously connected to the light emitting
module 14 of a plurality of the camera 1.
[0036] In the present embodiment, the lighting control module 16,
through the processing module 12 of the camera 1, is connected to
the light emitting module 14. However, practically, the lighting
control module 16 can also be connected directly to the light
emitting module 14. In addition, in the present embodiment, the
connection relationship and function of modules included in the
camera 1 is the same as the embodiment in the prior art and will
not be mentioned again here.
[0037] In addition, practically, the lighting control module 16 can
be installed within the data processing equipment, for example, the
computer, then through the data processing equipment, it is
connected to several cameras 1. When those cameras 1 are installed
at the same space, clear image of object within the space can then
be provided.
[0038] What needs to be noticed is, during the actual application,
the light emitting module 14 of the present invention can be
independent from the camera 1 to be placed at appropriate lighting
position to provide appropriate optical source to the camera 1.
[0039] Please also refer to FIGS. 3A to 3C, which illustrate
respectively, based on the present invention, the temporal
relationship between the light emitting period and LED light
emitting quantity. Among them, FIG. 3A illustrates the above
mentioned gradually increasing period; FIG. 3B illustrates the
gradually decreasing period; FIG. 3C illustrates the zig-zag (wavy)
period.
[0040] Please refer FIG. 4, which illustrates, based on one
embodiment of the present invention, the block diagram of the
camera control method. The camera, as mentioned above, includes a
light emitting module to emit light towards the recording
direction, and the light emitting module includes a plurality of
LEDs that can emit near infrared. As shown in FIG. 4, the method of
the present invention includes the following steps:
[0041] First, step S30 is performed. Then based on the image
captured by the camera, the environmental brightness in the
recording direction is calculated and brightness information is
then generated.
[0042] Next, step S31 is performed. Then based on brightness
information, the scope of the first brightness and the second
brightness is then adjusted.
[0043] Next, step S32 is carried out. Then based on LED quantity,
the light emitting period is decided. Practically, the unit length
of the light emitting period can be decided from the above
[equation 1], or decided based on other appropriate way by the
designer.
[0044] Finally, step S33 is carried out. That is, light emitted
from the light emitting module is controlled, within the above
light emitting period, to change from a first brightness to a
second brightness, and the circulation is repeated. That is, the
camera, within one light emitting period, can acquire the clear
images of objects at different depths of focus.
[0045] Practically, the above mentioned steps S30 and S31 do not
necessarily be implemented. The method of the present invention can
set up default value for the range of the first brightness and the
second brightness, for example, the first brightness is the maximum
brightness the light emitting module can emit (For example, when
all LEDs emit light), and second brightness is the minimum
brightness the light emitting module can emit (For example, only
one LED emits light), and it is true vice versa.
[0046] Furthermore, please also refer to FIGS. 5A to 5G and the
following table 1. FIGS. 5A to 5G illustrate the brightness
changing result based on the camera of the present invention, with
a distance between foreground object and camera of about 1.5
meters; table 1 lists the image analysis result from FIG. 5A to
FIG. 5G.
[0047] Among them, FIG. 5A is the image captured when all the LEDs
of the camera light up; FIG. 5B is the image captured when four
LEDs are closed; FIG. 5C is the image captured when eight LEDs are
closed; FIG. 5D is the image captured when 12 LEDs are closed; FIG.
5E is the image captured when 16 LEDs are closed; FIG. 5F is the
image captured when 20 LEDs are closed; and FIG. 5G is the image
captured when 24 LEDs are closed.
[0048] The statistical values in table 1 can be divided into three
types, namely: The mean of the grey value of each pixel within the
rectangular frame from FIG. 5A to 5G, standard deviation and the
mean of Sobel gradient values.
TABLE-US-00001 TABLE 1 FIG. 5A FIG. 5B FIG. 5C FIG. 5D FIG. 5E FIG.
5F FIG. 5G Mean 253.47 247.88 240.39 232.28 232.04 220.78 205.57
Standard 3.93 43.48 109.72 150.84 119.86 84.79 57.57 deviation Mean
of 6 29 69 113 90 78 52 Sobel gradient values
[0049] From these three data, we see that FIG. 5D has higher
standard deviation, which means that it has larger global change;
but the mean of Sobel gradient values is larger, which means that
it has larger local change. To sum up these two factors, the
contrast of human face of FIG. 5D is higher than that of other
figure. As compared to the image captured when the brightness is
not adjusted (as in FIG. 5A), FIG. 5D has higher human face
contrast and clarity.
[0050] Please refer together to FIG. 6A to 6F and the following
table 2. FIGS. 6A to 6F illustrate the brightness changing results
using the camera of the present invention with distance between the
foreground object to camera about 3 meters; table 2 lists the image
analysis result from FIG. 6A to 6F.
[0051] Among them, FIG. 6A is the image captured when all the LEDs
of the camera light up; FIG. 6B is the image captured when 4 LEDs
are closed; FIG. 6C is the image captured when 8 LEDs are closed;
FIG. 6D is the image captured when 12 LEDs are closed; FIG. 6E is
the image captured when 16 LEDs are closed; FIG. 6F is the image
captured when 20 LEDs are closed.
TABLE-US-00002 TABLE 2 FIG. 6A FIG. 6B FIG. 6C FIG. 6D FIG. 6E FIG.
6F Mean 253.82 245.42 234.60 218.98 205.04 202.64 Standard 0.98
76.00 138.34 96.94 69.60 40.38 deviation Mean of 5 44 107 125 71 57
Sobel gradient values
[0052] From these three data, we observe that FIG. 6C has higher
standard deviation, which means that it has larger global change;
however, FIG. 6D has larger mean of Sobel gradient value, which
means that it has larger local change. Therefore, human face
contrast of FIG. 6C and FIG. 6D is higher than that of other
figures. As compared to the image captured (as in FIG. 6A) when the
brightness is not adjusted, FIG. 6C and FIG. 6D all show higher
human face contrast and clarity.
[0053] From the above embodiment, we can observe that when the
object is about 1.5 meters to the camera, if image of higher
contrast of human face (high standard deviation) is to be obtained,
12 to 16 light emitting diodes need to be turned off; when the
object has a distance of 3 meters to the camera and if image of
higher human face contrast is to be obtained, 8 to 12 light
emitting diodes need to be turned off. However, if background image
of higher contrast is to be obtained, turnoff of zero light
emitting diode is a better choice. Therefore, the use of brightness
changing can let you obtain respective clear image of object of
different distance.
[0054] To sum up the above, the camera and the control method based
on the present invention can periodically control the light
emitting module of camera to emit light from high to low brightness
or from low to high brightness so that the camera, within a light
emitting period, can acquire clear images of objects of different
depths of focus, hence, the recognition rate at the back end
processing for night security surveillance can then be enhanced,
and the prior art issue can accordingly be solved.
[0055] Although the present invention is disclosed through a better
embodiment as above, yet it is not used to limit the present
invention, anyone that is familiar with this art, without deviating
the spirit and scope of the present invention, can make any kinds
of change, revision and finishing; therefore, the protection scope
of the present invention should be based on the scope as defined by
the following attached "what is claimed".
* * * * *