U.S. patent application number 16/365584 was filed with the patent office on 2020-10-01 for image processing method and system based on adjustments performed according to environment.
The applicant listed for this patent is GETAC TECHNOLOGY CORPORATION. Invention is credited to WU-CHIEH LIAO.
Application Number | 20200314319 16/365584 |
Document ID | / |
Family ID | 1000005087337 |
Filed Date | 2020-10-01 |
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United States Patent
Application |
20200314319 |
Kind Code |
A1 |
LIAO; WU-CHIEH |
October 1, 2020 |
IMAGE PROCESSING METHOD AND SYSTEM BASED ON ADJUSTMENTS PERFORMED
ACCORDING TO ENVIRONMENT
Abstract
An image processing method based on adjustments performed
according to environment includes capturing an environmental
parameter of an image, determining a scene mode of the image
according to the environmental parameter, estimating a brightness
correction parameter of the image according to the scene mode, and
performing an image area determination to obtain an image area and
an area brightness of the image area, followed by performing
brightness correction on the image according to the image area, the
area brightness and the brightness correction parameter, so as to
ensure image quality. An image processing system based on
adjustments performed according to environment is further
provided.
Inventors: |
LIAO; WU-CHIEH; (Taipei
City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GETAC TECHNOLOGY CORPORATION |
HSINCHU COUNTY |
|
TW |
|
|
Family ID: |
1000005087337 |
Appl. No.: |
16/365584 |
Filed: |
March 26, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 5/23229 20130101;
H04N 5/2353 20130101; H04N 5/2354 20130101 |
International
Class: |
H04N 5/235 20060101
H04N005/235; H04N 5/232 20060101 H04N005/232 |
Claims
1. An image processing method based on adjustments performed
according to environment, comprising the steps of: capturing an
environmental parameter of an image; determining a scene mode of
the image according to the environmental parameter; estimating a
first brightness correction parameter of the image according to the
scene mode; performing a first brightness correction on the image
as a whole according to the first brightness correction parameter;
and when the scene mode is a dark mode, performing the steps of:
performing an image area determination on the image to obtain an
image area, a background area, and an area brightness of the image
area; and performing a second brightness correction on the image
according to the image area, the area brightness of the image area
and a second brightness correction parameter, wherein the second
brightness correction comprises performing gamma correction on the
background area but not the image area when the scene mode is a
dark mode; wherein the image as a whole comprises the image area
and the background area.
2. (canceled)
3. The image processing method based on adjustments performed
according to environment according to claim 1, wherein the step of
obtaining the area brightness involves estimating an average
brightness of the image area such that the estimated average
brightness of the image area is regarded as the area
brightness.
4. The image processing method based on adjustments performed
according to environment according to claim 1, wherein the image
undergoes an automatic exposure process to obtain the environmental
parameter.
5. The image processing method based on adjustments performed
according to environment according to claim 4, wherein the
environmental parameter is a shutter speed and an ISO sensitivity
for use in obtaining the image.
6. The image processing method based on adjustments performed
according to environment according to claim 1, wherein the first
brightness correction parameter is a gamma correction value for
restoring the image brightness.
7. The image processing method based on adjustments performed
according to environment according to claim 1, wherein, in the step
of estimating the first brightness correction parameter of the
image, brightness of the image is restored to be proportionate to
brightness of a real scene and perceivable by a naked eye.
8. An image processing system based on adjustments performed
according to environment, comprising: an image-capturing unit for
capturing at least an image and obtaining an environmental
parameter of the image; a scene determining unit being in signal
connection with the image-capturing unit, determining a scene mode
of the image according to the environmental parameter generating a
first brightness correction parameter according to the scene mode;
an image area determination unit being in signal connection with
the image-capturing unit and performing an image area determination
on the image to obtain an image area, a background area, and an
area brightness of the image area; and an image correction unit
being in signal connection with the scene determining unit and the
image area determination unit, configured to perform the steps of:
perform a first brightness correction on the image as a whole
according to the first brightness correction parameter; and when
the scene mode is a dark mode, perform the steps of: performing a
second brightness correction on the image according to the image
area, the area brightness of the image area and a second brightness
correction parameter, wherein the second brightness correction
comprises performing gamma correction on the background area but
not the image area when the scene mode is a dark mode, wherein the
second brightness correction comprises performing gamma correction
on the background area but not the image area; wherein the image as
a whole comprises the image area and the background area.
9. (canceled)
10. The image processing system based on adjustments performed
according to environment according to claim 8, wherein the area
brightness is an average brightness of the image area.
11. The image processing system based on adjustments performed
according to environment according to claim 8, further comprising
an automatic exposure unit for performing automatic exposure on a
capturing environment of the image to enable the image-capturing
unit to capture the image in presence of supplemental light
provided by the automatic exposure unit and provide the
environmental parameter to the image-capturing unit.
12. The image processing system based on adjustments performed
according to environment according to claim 11, wherein the
environmental parameter is a shutter speed and an ISO sensitivity
for use in obtaining the image.
13. The image processing system based on adjustments performed
according to environment according to claim 8, wherein the first
brightness correction parameter is a gamma correction value for
restoring the image brightness.
14. The image processing method based on adjustments performed
according to environment according to claim 1, wherein the
background area is an entire remainder of the image outside the
image area.
15. The image processing system based on adjustments performed
according to environment according to claim 8, wherein the
background area is an entire remainder of the image outside the
image area.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present disclosure relates to image processing
technology and, more particularly, to an image processing method
and system based on adjustments performed according to
environment.
Description of the Prior Art
[0002] A dashcam of a moving car records the car's location,
condition, related data and captures a video of the surroundings.
Therefore, the dashcam can provide video evidence in the event of a
road accident.
[0003] The conventional dashcam has an image-capturing device. To
capture an image, the image-capturing device adjusts shutter speed
and ISO sensitivity (ISO value) automatically with an automatic
exposure unit such that the image has invariable brightness.
However, the aforesaid way of recording an image with invariable
brightness has a drawback: during nighttime, the car in the image
obtained looks sharp, but the background in the image obtained is
blurred and dim, thereby failing to ensure overall image
quality.
SUMMARY OF THE INVENTION
[0004] In view of the aforesaid drawback of the prior art, it is an
objective of the present disclosure to provide an image processing
method and system based on adjustments performed according to
environment, so as to ensure image quality adaptively.
[0005] In an embodiment, an image processing method based on
adjustments performed according to environment includes: capturing
an environmental parameter of an image; determining a scene mode of
the image according to the environmental parameter; estimating a
brightness correction parameter of the image according to the scene
mode; and performing an image area determination to obtain an image
area and an area brightness of the image area, followed by
performing brightness correction on the image according to the
image area, the area brightness and the brightness correction
parameter.
[0006] In some embodiments, the brightness correction involves
performing gamma correction on background in the image when the
scene mode is a dark mode.
[0007] In an embodiment, an image processing system based on
adjustments performed according to environment includes an
image-capturing unit, a scene determining unit, an image area
determination unit and an image correction unit. The
image-capturing unit captures at least an image and obtains an
environmental parameter of the image. The scene determining unit
and the image area determination unit are in signal connection with
the image-capturing unit. The scene determining unit determines a
scene mode of the image according to the environmental parameter
and generates a brightness correction parameter according to the
scene mode. The image area determination unit performs an image
area determination on the image to obtain an image area and an area
brightness of the image area. The image correction unit is in
signal connection with the scene determining unit and the image
area determination unit to perform brightness correction on the
image according to the image area, the area brightness and the
brightness correction parameter.
[0008] In some embodiments, when the scene determining unit
determines the scene mode of the image to be a dark mode, the
brightness correction involves performing gamma correction on
background in the image.
[0009] In conclusion, a captured image varies with a variable
environment. Therefore, the present disclosure is advantageous in
that image processing is carried out to an image according to
environment to perform brightness correction on each image
appropriately, so as to ensure image quality.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic view of an image processing system
according to an embodiment of the present disclosure;
[0011] FIG. 2 is a schematic view of a scene mode divided into four
sectors according to a gamma value according to an embodiment of
the present disclosure;
[0012] FIG. 3 is a schematic view of a process flow of an image
processing method according to an embodiment of the present
disclosure;
[0013] FIG. 4 is a schematic view of a process flow of the image
processing method according to another embodiment of the present
disclosure;
[0014] FIG. 5 is a schematic view of a process flow of the image
processing method according to yet another embodiment of the
present disclosure;
[0015] FIG. 6 is a graph of gamma correction according to an
embodiment of the present disclosure; and
[0016] FIG. 7 is a graph of gamma correction according to another
embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0017] FIG. 1 is a schematic view of an image processing system
according to an embodiment of the present disclosure. Referring to
FIG. 1, the image processing system 10, which is based on
adjustments performed according to environment, includes an
image-capturing unit 12, a scene determining unit 14, an image area
determination unit 16, an image correction unit 18 and an automatic
exposure unit 20.
[0018] The image-capturing unit 12 captures at least an image from
outside and obtains an environmental parameter of the image. The
automatic exposure unit 20 is in signal connection with the
image-capturing unit 12. The automatic exposure unit 20 performs
automatic exposure on image-capturing environment to enable the
image-capturing unit 12 to capture the image in the presence of
supplemental light provided by the automatic exposure unit 20 and
provide the environmental parameter to the image-capturing unit 12.
In some embodiments, the image-capturing unit 12 is an image
sensing component, such as a charge coupled device (CCD) or a
complementary metal-oxide-semiconductor (CMOS).
[0019] In some embodiments, the environmental parameter is a
shutter speed and an ISO sensitivity for use in obtaining the
image, that is, the actual values obtained as a result of automatic
exposure performed by the automatic exposure unit 20 on the
image-capturing environment at the moment when the image-capturing
unit 12 obtains the image.
[0020] The scene determining unit 14 is in signal connection with
the image-capturing unit 12 to determine, according to the
environmental parameter, a scene mode which the image is attributed
to, and generate a brightness correction parameter according to the
scene mode. In an embodiment, the brightness correction parameter
is a gamma correction value for restoring image brightness. The
image area determination unit 16 is in signal connection with the
image-capturing unit 12. The image area determination unit 16
performs an image area determination on the captured image to
obtain an image area and an area brightness of the image area. The
image correction unit 18 is in signal connection with the scene
determining unit 14 and the image area determination unit 16 such
that the image correction unit 18 can perform brightness correction
on the image according to the obtained image area, area brightness
and brightness correction parameter. Therefore, the brightness of
the image is restored to be proportionate to that of the real scene
and perceivable by the naked eye. In some embodiments, the area
brightness is the average brightness of the image area obtained by
the image area determination unit 16, and the image area is the
whole area of the image or a partial area of the image.
[0021] In some embodiments, the image correction unit 18 is an
image signal processing chip (ISP).
[0022] The image processing system 10 further has a light
measurement unit 22 in signal connection with the image area
determination unit 16 and the image correction unit 18. When the
image area determination unit 16 provides the location and
magnitude of the image area to the light measurement unit 22, the
light measurement unit 22 performs light measurement on the image
area such that the image area is subjected to optimal exposure, so
as to estimate brightness of the current frame according to the
image area and thereby ensure optimal area brightness.
[0023] In some embodiments, after being completely corrected by the
image correction unit 18, the image is compressed by an image
compression unit 24 to become image data. Then, the image data is
output to a storage unit or an external device for back-end
storage.
[0024] In some embodiments, different scene modes are determined
according to the environmental parameter, i.e., the shutter speed
and the ISO sensitivity. Referring to FIG. 2, since both the
shutter speed and the ISO sensitivity are directly proportional to
the exposure value, both the exposure value and alpha (.alpha.)
value are directly proportional to gamma (.gamma.) value or each
exposure value corresponds to a gamma value, such that a look up
table (LUT) is created. In the LUT, the alpha value is a conversion
variable for correlating the exposure value with the gamma value,
as shown in expressions below.
shutter speed (second).times.ISO sensitivity=exposure value
exposure value.times.alpha value=gamma value or LUT (exposure
value)=gamma value
[0025] The gamma value can be inferred from the shutter speed and
the ISO sensitivity, using the expressions, and then a scene mode
of the image is determined according to the gamma value. Referring
to FIG. 2, the scene mode is divided into four sectors according to
the gamma value. However, the present disclosure is not restrictive
of the number of the sectors. In practice, the more the sectors
are, the better the efficacy is. To increase the number of the
sectors, the number of the sectors can be adjusted according to a
user or system. In this embodiment, the four sectors are, from low
to high gamma values, glaring mode (gamma=0.35, noon), bright mode
(gamma=0.45, morning and afternoon), dim mode (gamma=0.55, dawn and
dusk), and dark mode (gamma=0.65, night). The dark mode occurs at
night or any other circumstances where there is a lack of
illumination (gamma .gtoreq.0.65).
[0026] When the scene determining unit 14 determines the scene mode
of the image to be the dark mode, the image correction unit 18
performs brightness correction by performing gamma correction on
the background in the image rather than the image area in the
image, so as to restore background brightness. In an embodiment,
when the scene mode is determined to be the dark mode, the image
area is determined to be a partial area, wherein the background in
the image is outside the image area in the image, causing the image
area determination unit 16 to obtain the image area and the area
brightness of the image area, further causing the image correction
unit 18 to perform brightness correction on the background in the
image rather than the image area in the image according to the
image area, the area brightness, and the brightness correction
parameter, allowing the brightness surrounding the image area in
the image to equal the brightness within the image area in the
image. Therefore, the brightness of the whole image is restored to
the brightness of the real scene to thereby eliminate any
difference in brightness between the image area and the background;
otherwise, the background is blurred and dim.
[0027] In some embodiments, the image-capturing unit 12, the image
correction unit 18, the automatic exposure unit 20, the light
measurement unit 22, and the image compression unit 24 are built-in
components of an image-capturing device, such as a camera or a
camcorder. The scene determining unit 14 and the image area
determination unit 16 are provided in a dashcam or an engine system
of a car. In some further embodiments, the image-capturing unit 12,
the scene determining unit 14, the image area determination unit
16, the image correction unit 18, the automatic exposure unit 20,
the light measurement unit 22 and the image compression unit 24 are
integrated into the same image-capturing device.
[0028] Referring to FIG. 1 through FIG. 3, the image processing
method based on adjustments performed according to environment
includes the steps of: capturing an environmental parameter of an
image with an image-capturing unit 12 (step S10) and performing an
automatic exposure process on the image with the automatic exposure
unit 20 to obtain an environmental parameter of the image, such as
shutter speed and ISO sensitivity; determining a scene mode of the
image with the scene determining unit 14 according to the
environmental parameter (step S12), wherein the scene mode is
exemplified by a glaring mode, a bright mode, a dim mode, and a
dark mode; estimating a brightness correction parameter of the
image with the scene determining unit 14 according to the scene
mode (step S14) to obtain a gamma correction value of each image;
performing an image area determination with the image area
determination unit 16 to obtain an image area of the image and an
area brightness of the image area, followed by performing
brightness correction on the image with the image correction unit
18 according to the image area, the area brightness and the
brightness correction parameter (step S16). In an embodiment, in
the step of obtaining the area brightness, the image area
determination unit 16 operates in conjunction with the light
measurement unit 22 to estimate the average brightness of the image
area such that the estimated average brightness of the image area
is regarded as the area brightness.
[0029] In some embodiments, as shown in FIG. 4, after the step of
obtaining the brightness correction parameter (gamma correction
value) of the image (step S14), the image correction unit 18
performs brightness correction on the image according to the
brightness correction parameter (step S15) such that the brightness
of the image is restored to be proportionate to that of the real
scene and perceivable by the naked eye. Afterward, the step of
image area determination is performed (step S16). The other steps
are the same as those of the method in the embodiment illustrated
by FIG. 3 and thus, for the sake of brevity, are not
reiterated.
[0030] In some embodiments, to clarify the complete process flow of
the image processing method, the image area is configured to be a
partial area where a preceding car is present and is known as
preceding car area. The following embodiment is exemplified by the
preceding car area and described in detail. Referring to FIG. 1,
FIG. 2 and FIG. 5, the image processing method including the steps
of capturing an environmental parameter of a plurality of images
(step S20), capturing the images sequentially with the
image-capturing unit 12, and performing an automatic exposure
process on each image with the automatic exposure unit 20 to obtain
the environmental parameter of the images, such as shutter speed
and ISO sensitivity. The scene determining unit 14 determines the
scene mode of the images according to the environmental parameter
(step S21). For instance, the scene mode is a glaring mode (which
occurs at noon), a bright mode (which occurs in the morning and
afternoon), a dim mode (which occurs at dawn and dusk), or a dark
mode (which occurs at night), but the present disclosure is not
limited thereto. Whatever the scene mode, the scene determining
unit 14 always estimates the brightness correction parameter of
each image according to the scene mode (step S22) to obtain the
gamma correction value of each image. After the brightness
correction parameter of each image has been obtained, the image
correction unit 18 performs brightness correction on the whole
frame of each image according to the brightness correction
parameter (step S23) such that the brightness of an image is
restored to be proportionate to that of the real scene and
perceivable by the naked eye. Since the scene mode of each image is
determined in step S21, step S24 involves determining whether an
image is attributed to the dark mode. In step S24, a negative
determination causes termination of the process flow the correction
processing of the image (step S27), whereas an affirmative
determination causes the image area determination unit 16 to
perform a preceding car area determination (step S25) and thereby
obtain a preceding car area in the image and an area brightness of
the preceding car area, wherein the area brightness is the average
brightness of the preceding car area and can be obtained by the
light measurement unit 22. Afterward, the image correction unit 18
performs background brightness correction on the image according to
the preceding car area, area brightness and brightness correction
parameter (step S26), that is, performs gamma correction on the
background area such that the brightness surrounding the preceding
car area in the image equals the brightness within the preceding
car area in the image, allowing the brightness of the image to be
restored to be proportionate to that of the real scene and thereby
precluding any difference in brightness between the preceding car
area and the background (the brightness difference renders the car
image sharp and the background image blurred). Upon completion of
the step of background brightness correction performed on each
image in the dark mode, the process flow of the correction
processing of the image terminates (step S27).
[0031] In some embodiments, when the image is determined to be
attributed to the dark mode, brightness correction involves
performing gamma correction on the background in the image (to
correct the brightness surrounding the preceding car area in the
image.) Referring to FIG. 6, the dashed line denotes pre-adjustment
background brightness, whereas the solid line denotes
post-adjustment background brightness, with the preceding car area
brightness L functioning as a standard, the brightness of the input
image is adjusted according to a brightness ratio, for example,
increasing 25% brightness to 50% brightness, increasing 50%
brightness to 90% brightness, so as to perform gamma correction
according to the ratio. Referring to FIG. 7, the dashed line
denotes pre-adjustment background brightness, whereas the solid
line denotes post-adjustment background brightness, with the
preceding car area brightness L functioning as a standard, the
brightness of the input image is increased according to the gamma
curve (gamma value .gamma.=0.3), so as to perform gamma correction
according to the gamma value, thereby adjusting the background
brightness. In an embodiment, the gamma value is a predetermined
parameter, for example, a parameter predetermined according to
measurement performed before installation.
[0032] Therefore, a captured image varies with a variable
environment. For instance, when the image processing method and
system of the present disclosure are applied to a dashcam, the
environment of the captured image changes while the car is moving.
Therefore, the present disclosure is advantageous in that image
processing is carried out to an image according to environment to
perform brightness correction on each image appropriately and
thereby enhance image quality, so as to ensure image quality
adaptively. Furthermore, when applied to special use, the image
processing system of the present disclosure ensures optimal
efficacy. For instance, when applied to a dashcam mounted on a
police car, the image processing system of the present disclosure
ensures that all the captured images are sharp and the backgrounds
are not blurred or dim such that the dashcam mounted on the police
car can provide video evidence in the event of a road accident.
[0033] The features and advantages of the present disclosure are
illustrated by the embodiments of the present disclosure to enable
persons skilled in the art to gain insight into the technical
disclosure in the present disclosure and implement the present
disclosure accordingly. The embodiments of the present disclosure
are not restrictive of the claims of the present disclosure.
Equivalent changes or modifications made to the embodiments of the
present disclosure in accordance with the spirit embodied in the
present disclosure must be deemed falling within the scope of the
present disclosure.
* * * * *