U.S. patent application number 15/016590 was filed with the patent office on 2017-08-10 for method and apparatus for automatic stage scene detection.
The applicant listed for this patent is Motorola Mobility LLC. Invention is credited to Yin-Hu Chen, Valeriy Marchevsky, Peter A. Matsimanis.
Application Number | 20170230559 15/016590 |
Document ID | / |
Family ID | 59410883 |
Filed Date | 2017-08-10 |
United States Patent
Application |
20170230559 |
Kind Code |
A1 |
Chen; Yin-Hu ; et
al. |
August 10, 2017 |
METHOD AND APPARATUS FOR AUTOMATIC STAGE SCENE DETECTION
Abstract
A method and apparatus provide automatic stage scene detection.
A first image of a scene can be captured using a frame luma for
automatic exposure control. A brightness contrast can be calculated
between a center region of the first image and areas surrounding
the center region of the first image. A brightness value can be
ascertained for the entire first image. The first image can be
determined to be a stage scene image based on the brightness
contrast being greater than a stage scene contrast threshold and
the brightness value for the entire first image being less than a
stage scene brightness value threshold. The frame luma for the
automatic exposure control can be adjusted for correct exposure of
the center region of the first image in response to determining the
first image is a stage scene.
Inventors: |
Chen; Yin-Hu; (Deerfield,
IL) ; Marchevsky; Valeriy; (Glenview, IL) ;
Matsimanis; Peter A.; (Glenview, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Motorola Mobility LLC |
Chicago |
IL |
US |
|
|
Family ID: |
59410883 |
Appl. No.: |
15/016590 |
Filed: |
February 5, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 5/2351 20130101;
H04N 9/833 20130101; H04N 5/2354 20130101; H04N 5/2352 20130101;
H04N 5/2353 20130101; H04N 5/2356 20130101; H04N 5/57 20130101 |
International
Class: |
H04N 5/235 20060101
H04N005/235 |
Claims
1. A method comprising: capturing a first image of a scene using a
frame luma for automatic exposure control; calculating a brightness
contrast between a center region of the first image and areas
surrounding the center region of the first image; ascertaining a
brightness value for the entire first image; determining the first
image is a stage scene image based on the brightness contrast being
greater than a stage scene contrast threshold and the brightness
value for the entire first image being less than a stage scene
brightness value threshold; adjusting the frame luma for the
automatic exposure control for correct exposure of the center
region of the first image in response to determining the first
image is a stage scene; and capturing a second image of the scene
based on automatic exposure control using the adjusted frame
luma.
2. The method according to claim 1, further comprising: calculating
a number of saturated sub-regions in the center region, wherein
determining comprises determining the first image is a stage scene
image based on the brightness contrast being greater than a stage
scene contrast threshold, the brightness for the entire first image
value being less than a stage scene brightness value threshold, and
the number saturated sub-regions in the center region being higher
than a saturated regions threshold.
3. The method according to claim 2, wherein calculating the number
of saturated sub-regions in the center region comprises:
determining whether each sub-region in the center region has a
brightness greater than a saturated sub-region brightness value
threshold; and adding the number of sub-regions with a brightness
greater than the saturated sub-region brightness value threshold to
calculate the number of saturated sub-regions in the center
region.
4. The method according to claim 1, further comprising: calculating
a number of dark sub-regions in areas surrounding the center
region, wherein determining comprises determining the first image
is a stage scene image based on the brightness contrast being
greater than a stage scene contrast threshold, the brightness value
for the entire first image being less than a stage scene brightness
value threshold, and the number of dark sub-regions in the areas
surrounding the center region being higher than a dark regions
threshold.
5. The method according to claim 4, wherein calculating the dark
sub-regions in the areas surrounding the center region comprises:
determining whether each sub-region in the dark areas surrounding
the center region has a brightness less than a dark sub-region
brightness value threshold; and adding the number of sub-regions
with a brightness less than the dark sub-region brightness value
threshold to calculate the number of dark sub-regions in the areas
surrounding the center region.
6. The method according to claim 1, wherein adjusting the frame
luma for the automatic exposure control comprises decreasing a
target luma for proper exposure of the center region of the
image.
7. The method according to claim 1, wherein adjusting the frame
luma for the automatic exposure control comprises calculating the
frame luma only based on the center region of the image for proper
exposure of the center region of the image.
8. The method according to claim 1, wherein ascertaining a
brightness value of the first image comprises ascertaining the
brightness value using an ambient light sensor to evaluate ambient
light brightness for the brightness value.
9. The method according to claim 1, further comprising outputting
the second image.
10. An apparatus comprising: a sensor to capture a first image of a
scene using a frame luma for automatic exposure control; and a
controller to calculate a brightness contrast between a center
region of the first image and areas surrounding the center region
of the first image, ascertain a brightness value for the entire
first image, determine the first image is a stage scene image based
on the brightness contrast being greater than a stage scene
contrast threshold and the brightness value for the entire first
image being less than a stage scene brightness value threshold, and
adjust the frame luma for the automatic exposure control for
correct exposure of the center region of the first image in
response to determining the first image is a stage scene, wherein
the sensor captures a second image of the scene based on automatic
exposure control using the adjusted frame luma.
11. The apparatus according to claim 10, wherein the controller
calculates a number of saturated sub-regions in the center region,
and determines the first image is a stage scene image based on the
brightness contrast being greater than a stage scene contrast
threshold, the brightness value for the entire first image being
less than a stage scene brightness value threshold, and the number
saturated sub-regions in the center region being higher than a
saturated regions threshold.
12. The apparatus according to claim 11, wherein the controller
calculates the number of saturated sub-regions in the center region
by determining whether each sub-region in the center region has a
brightness greater than a saturated sub-region brightness value
threshold, and adding the number of sub-regions with a brightness
greater than the saturated sub-region brightness value threshold to
calculate the number of saturated sub-regions in the center
region.
13. The apparatus according to claim 10, wherein the controller
calculates a number of dark sub-regions in the areas surrounding
the center region, and determines the first image is a stage scene
image based on the brightness contrast being greater than a stage
scene contrast threshold, the brightness for the entire first image
value being less than a stage scene brightness value threshold, and
the number of dark sub-regions in the areas surrounding the center
region being higher than a dark regions threshold.
14. The apparatus according to claim 13, wherein the controller
calculates the dark sub-regions in the areas surrounding the center
region by determining whether each sub-region in the dark areas has
a brightness less than a dark sub-region brightness value
threshold, and adding the number of sub-regions with a brightness
less than the dark sub-region brightness value threshold to
calculate the number of dark sub-regions in the areas surrounding
the center region.
15. The apparatus according to claim 10, wherein the controller
adjusts the frame luma for the automatic exposure control by
decreasing a target luma for proper exposure of the center region
of the image.
16. The apparatus according to claim 10, wherein the controller
adjusts the frame luma for the automatic exposure control by
calculating the frame luma only based on the center region of the
image for proper exposure of the center region of the image.
17. The apparatus according to claim 10, wherein the controller
ascertains a brightness value of the first image using an ambient
light sensor to evaluate ambient light brightness for the
brightness value.
18. The apparatus according to claim 10, further comprising an
output to output the second image.
19. The apparatus according to claim 10, wherein the apparatus
comprises a smartphone.
20. A method comprising: capturing a first image of a scene using a
frame luma for automatic exposure control; calculating a brightness
contrast between a bright center region of the first image and dark
areas surrounding the center region of the first image;
ascertaining a brightness value for the entire first image;
calculating a number of saturated sub-regions in the center region;
calculating a number of dark sub-regions in the dark areas
surrounding the center region; determining the first image is a
stage scene image based on the brightness contrast being greater
than a stage scene contrast threshold, the brightness value for the
entire first image being less than a stage scene brightness value
threshold, the number saturated sub-regions in the center region
being higher than a saturated regions threshold, and the number of
dark sub-regions in the dark areas being higher than a dark regions
threshold; adjusting the frame luma for the automatic exposure
control for correct exposure of the center region of the first
image in response to determining the first image is a stage scene;
capturing a second image of the scene based on automatic exposure
control using the adjusted frame luma; and outputting the second
image.
Description
BACKGROUND
[0001] 1. Field
[0002] The present disclosure is directed to a method and apparatus
for automatic stage scene detection. More particularly, the present
disclosure is directed to automatically detecting a stage scene and
adjusting exposure to capture an image of the stage scene.
[0003] 2. Introduction
[0004] Presently, people take pictures and videos using portable
devices that have cameras. Such portable devices can include
smartphones, tablet computers, flip phones, point and shoot
cameras, DSLR cameras, laptop computers, and other portable devices
that include cameras. These devices include automatic exposure
control algorithms that automatically sets the exposure so the
pictures and videos show proper illumination of the subject matter
in a scene.
[0005] Unfortunately, automatic exposure control algorithms cannot
account for stage scenes where a portion of a scene is brightly
illuminated and the rest of the scene is dark. For example,
performers on stage at a concert or in a club are brightly
illuminated while the audience and surrounding areas are kept dark
to focus the audience's attention on the performers. When an
attendee attempts to take a picture, their device will consider
both the dark areas and the light areas when setting the exposure
of the camera. Because the camera sensor has a limited sensitivity
range, both the light areas and the dark areas cannot be properly
exposed at the same time. This results in the light area of the
captured image being overblown and the dark area being underexposed
when the device averages out the exposure of the two areas. This
happens because the device does not know the scene is a stage scene
where the subject of the scene is illuminated drastically brighter
than the surrounding area.
[0006] Thus, there is a need for a method and apparatus for
automatic stage scene detection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In order to describe the manner in which advantages and
features of the disclosure can be obtained, a description of the
disclosure is rendered by reference to specific embodiments thereof
which are illustrated in the appended drawings. These drawings
depict only example embodiments of the disclosure and are not
therefore to be considered to be limiting of its scope.
[0008] FIG. 1 is an example block diagram of a system according to
a possible embodiment
[0009] FIG. 2 is an example illustration of regions of an image
according to a possible embodiment;
[0010] FIG. 3 is an example flowchart illustrating the operation of
a portable device according to a possible embodiment;
[0011] FIG. 4 is an example flowchart illustrating the operation of
a portable device according to a possible embodiment;
[0012] FIG. 5 is an example block diagram of an apparatus according
to a possible embodiment;
[0013] FIG. 6 is an example representation of an image captured
without stage scene detection and compensation according to a
possible embodiment; and
[0014] FIG. 7 is an example representation of an image captured
with stage scene detection and compensation according to a possible
embodiment.
DETAILED DESCRIPTION
[0015] Embodiments provide a method and apparatus for automatic
stage scene detection. According to a possible embodiment, a first
image of a scene can be captured using a frame luma for automatic
exposure control. A brightness contrast can be calculated between a
center region of the first image and areas surrounding the center
region of the first image. A brightness value can be ascertained
for the entire first image. The first image can be determined to be
a stage scene image based on the brightness contrast being greater
than a stage scene contrast threshold and the brightness value for
the entire first image being less than a stage scene brightness
value threshold. The frame luma for the automatic exposure control
can be adjusted for correct exposure of the center region of the
first image in response to determining the first image is a stage
scene. A second image of the scene can be captured based on
automatic exposure control using the adjusted frame luma.
[0016] FIG. 1 is an example block diagram of a system 100 according
to a possible embodiment. The system 100 can include an apparatus
110 and a stage scene 150. The stage scene 150 can be an indoor
stage scene, an outdoor stage scene at night, an amphitheater stage
scene, a scene with a spotlight on a subject, or any other scene
where a subject near the center 152 of scene is more brightly lit
than the surrounding areas 154 of the scene. The apparatus 110 can
be a wireless terminal, a portable wireless communication device, a
smartphone, a cellular telephone, a flip phone, a personal digital
assistant, a personal computer, a selective call receiver, a tablet
computer, a laptop computer, a camera apparatus or any other device
that is capable of capturing an image of a scene. The apparatus 110
can include a camera module 120, a controller 130, and an output
140. The controller 130 can be a microprocessor, a digital signal
processor, an image processor, an image processing engine, a media
processor, hardware, software, or any other device that can process
an image. The camera module 120 can include a lens 122 and a sensor
124. The sensor 124 can be a Bayer grid sensor, a Red Green Blue
Clear (RGBC) sensor, a luminance and chrominance sensor, such as a
YUV sensor, an infrared sensor, a Complementary Metal Oxide
Semiconductor (CMOS) sensor, a Charge-Coupled Device (CCD) sensor,
and/or any other sensor that can be used to capture an image. The
output 140 can be a display, can be an output from the controller
130 to a memory, can be a memory card reader output, can be a
transceiver, can be a local port, and/or can be any other output
that can output an image.
[0017] In operation, the sensor 124 can capture a first image of
the scene 150 using a frame luma for automatic exposure control.
The controller 130 can calculate a brightness contrast between a
center region 152 of the first image and areas 154 surrounding the
center region of the first image. The controller 130 can ascertain
a brightness value for the entire first image. The controller 130
can determine the first image is a stage scene image based on the
brightness contrast being greater than a stage scene contrast
threshold and the brightness value for the entire first image being
less than a stage scene brightness value threshold. The controller
130 can adjust the frame luma for the automatic exposure control
for correct exposure of the center region of the first image in
response to determining the first image is a stage scene. The
sensor 124 can capture a second image of the scene based on
automatic exposure control using the adjusted frame luma. The
second image can be a still image or frame in a picture or a frame
of multiple frames in a video.
[0018] FIG. 2 is an example illustration of regions of an image 200
according to a possible embodiment. A standard Automatic Exposure
Control (AEC) algorithm runs on Bayer Grid (BG) stats of a Field of
View (FOV) of the image 200. The BG stats can be divided by
M.times.N regions, such as 64.times.48 regions and the average
luminance (Y) for each region is be calculated from the BG stats
(R,Gr,B,Gb). A normal standard AEC algorithm uses frame average or
weighted, such as center weighted or spot weighted, luminance to
calculate the frame luma from each region and its weighting with
the following formula:
Frame_Luma = [ ( Y sum [ i ] .times. W [ i ] ) W [ i ] ] ,
##EQU00001##
where i represents each region. The AEC algorithm can use average
luminance, center weighted luminance, such as where the center
regions get a weighting of 2.40 and surrounding regions get a
weighting of 0.533, spot weighted luminance, or other indicators of
luminance to determine the frame luma. The AEC algorithm can
compare the frame luma with pre-defined luma target. If the frame
luma is within a tolerance, the AEC is settled and the algorithm
can write the line-count and gain from a sensor-specific exposure
table to the sensor 124 to control the sensitivity.
[0019] A standard AEC algorithm cannot handle a stage scene because
the scene has very high dynamic range, with certain regions of the
scene in low light or in the dark and some regions very bright. The
normal standard AEC algorithm gives desired results only for the
average or weighted frame luma, and is not capable of handling the
high dynamic range scene of a stage scene, which can also be
considered a concert scene, a spotlight scene, or other scene that
has a high dynamic range between a bright central area and
surrounding dark areas. For example, as stage scenes can happen
indoors with certain proportion of the regions in low light or in
the dark, a normal standard AEC will use longer exposure time, and
will get the stage area highlight region totally over-blown. Thus,
the AEC needs to handle stage scenes differently from other scenes
to avoid impacting the other scenes. Embodiments can employ
algorithm to detect and handle stage scenes automatically. This
special handling of AEC enhancement can be used for the stage
scenes, while the normal standard AEC can apply to all other
scenes.
[0020] FIG. 3 is an example flowchart 300 illustrating the
operation of a portable device including a camera according to a
possible embodiment. At 310, the AEC on the device can run a stage
scene detection algorithm At 320, the device can determine if the
scene is a stage scene. At 330, if the scene is a stage scene, AEC
enhancement can be applied for the stage scene. At 340, if the
scene is not a stage scene, normal standard AEC can be applied.
[0021] Stage scenes have certain properties that can be used to
determine if the scene is a stage scene. One property is that a
stage scene has a very high dynamic range, with a central area very
bright and surrounding areas dim or dark. Another property is that
a stage scene is typically an indoor scene or night outdoor scene
with a low overall Brightness Value (BV). Another property is that
some regions are oversaturated in the central bright/highlight
area. Another property is some regions in the surrounding shadow
areas of a stage scene are dark. Some or all of these properties
can be used to determine if a scene is a stage scene.
[0022] To automatically detect a stage scene, the brightness
contrast ratio between the stage highlight area and the surrounding
shadow area can be calculated to determine the high dynamic range
level. Among the whole M.times.N grid BG stats, such as a
64.times.48 grid, of the FOV, an area can be defined that is used
for stage highlight region, such as a 24.times.18 area for the
region. The average Y of this 24.times.18 highlight regions can be
calculated as Y_highlight and the average Y of the surrounding
regions can be calculated as Y_shadow. The brightness contrast
ratio, B_contrast, can be determined based on
Y_highlight/Y_shadow.
[0023] Also, the Brightness Value (BV) of the whole frame or the
exposure_index of the whole frame can be obtained from the normal
standard AEC algorithm A typical stage scene happens indoor or at
night, so use the BV value or exposure_index can be used to
determine the scene is an indoor or outdoor stage scene based on
overall brightness being low to differentiate the stage scene from
otherwise bright scenes that are not stage scenes. As an alternate
from normal standard AEC algorithm detecting the brightness for a
stage scene, an Ambient Light Sensor (ALS) can be used to evaluate
the ambient light brightness.
[0024] Additionally, a number of saturated regions can be
calculated from the pre-defined highlight area, such as the
24.times.18 grid, from BG stats as stage_saturated_regions_num. For
example, for each region of the pre-defined highlight area, such as
in 24.times.18 regions, if the average Y of the region is bigger
than certain threshold, such as 250 on a 0.about.255 scale of
brightness, this region can be counted as saturated region, and
stage_saturated_regions_num can be increased by 1.
[0025] Furthermore, the number of dark regions can be calculated
from the surrounding shadow area from BG stats as
stage_darkness_regions_num. For example, for each region of the
surrounding area, such as in 64.times.48-24.times.18 regions, if
the average Y of the region is less than certain threshold, such as
1 on a 0.about.255 scale of brightness, this region can be counted
as dark region and stage_darkness_regions_num can be increased by
1.
[0026] Tunable parameters for can be defined for detection of a
stage scene. These parameters can include stage_scene_contrast
threshold to check the dynamic range level,
stage_scene_BV_threshold to check whether it is a stage scene with
a low BV value, stage_scene_saturated_regions_threshold, to check
whether the scene has a certain number of saturated regions, and
stage_scene_darkness_regions_threshold, to check whether the scene
has a certain number of dark regions.
[0027] The scene can classified as stage/concert scene if some or
all the following conditions are met: the brightness contrast
B_contrast is bigger than threshold stage_scene_contrast_threshold;
the frame BV value is less than threshold Stage_scene_BV_threshold;
the highlight area saturated regions number
stage_saturated_regions_num is bigger than threshold
stage_scene_saturated_regions_threshold; and/or the surrounding
shadow area darkness regions number stage_darkness_regions_num is
bigger than threshold Stage_scene_darkness_regions_threshold.
[0028] When a stage scene is detected, AEC enhancement methods can
be used based on the luma target to get the stage area properly
exposed. For example, the luma target can be decreased. With the
lower luma target, the exposure integration time can be shorter and
the bright highlight region of stage area can be properly exposed,
instead of overexposed. As another example, the frame_luma can be
calculated only based on the stage area and the dark surrounding
area can be discarded from the calculated, which will make the
stage area properly exposed as only stage area stats can be
considered.
[0029] FIG. 4 is an example flowchart 400 illustrating the
operation of a portable device, such as the apparatus 110,
according to a possible embodiment. The operation can be done in
both non-zoom captures and zoom captures with different Bayer grid
stats, grid sizes, RGBC stats, or other zoom captures. According to
a possible embodiment, digital or optical zooming can be used on
the subject of an image to reduce effects of the background and
ensure the stage area of a scene fills most of the image.
[0030] At 410, a first image of a scene can be captured using a
frame luma for automatic exposure control. The first image can be a
preview image, a frame buffer image, or any other image that can be
obtained from an image sensor to determine exposure.
[0031] At 415, a brightness contrast can be calculated between a
center region of the first image and areas surrounding the center
region of the first image. For example, a brightness contrast can
be calculated between a central bright region and a surrounding
dark region.
[0032] At 420, a determination can be made as to whether the
brightness contrast is greater than a stage scene contrast
threshold. For example, the brightness contrast can be compared to
stage_scene_contrast_threshold. If it is greater, the flowchart 400
can advance to block 425. If not, the flowchart 400 can advance to
block 470.
[0033] At 425, a brightness value can be ascertained for the entire
first image. The brightness value can be any value representing
brightness and can include an exposure index parameter, can be the
result of a line count multiplied by sensor gain, can be a
luminance parameter, or can be any other value that represents the
brightness of a scene. According to a possible embodiment, the
brightness value can be ascertained using an ambient light sensor
to evaluate ambient light brightness for the brightness value.
According to another possible embodiment, the brightness value can
be ascertained from the first image without employing an ambient
light sensor, such as by using an AEC algorithm.
[0034] At 430, a determination can be made as to whether the
brightness value for the entire first image is less than a stage
scene brightness value threshold. For example, the brightness value
can be compare to stage_scene_BV_threshold. If it is less, the
flowchart 400 can advance to block 435. If not, the flowchart 400
can advance to block 470.
[0035] At 435, a number of saturated sub-regions in the center
region can be calculated. For example, the number of saturated
sub-regions in the center region can be calculated by determining
whether each sub-region in the center region has a brightness
greater than a saturated sub-region brightness value threshold and
then adding the number of sub-regions with a brightness greater
than the saturated sub-region brightness value threshold to
calculate the number of saturated sub-regions in the center region.
For example, the center region can be broken up into a number of
sub-regions and the average brightness of each sub-region can be
compared to the saturated region brightness value threshold. As a
further example, the number of saturated regions in a central
highlight region can be calculated.
[0036] At 440, a determination can be made as to whether the number
saturated sub-regions in the center region is higher than a
saturated regions threshold. For example, the number of saturated
sub-regions can be compared to
Stage_scene_saturated_regions_threshold. If it is greater, the
flowchart 400 can advance to block 445. If not, the flowchart 400
can advance to block 470.
[0037] At 445, a number of dark sub-regions in areas surrounding
the center region can be calculated. For example, the dark
sub-regions in the areas surrounding the center region can be
calculated by determining whether each sub-region in the dark areas
surrounding the center region has a brightness less than a dark
sub-region brightness value threshold and then adding the number of
sub-regions with a brightness less than the dark sub-region
brightness value threshold to calculate the number of dark
sub-regions in the areas surrounding the center region. As a
further example, a number of dark regions of a surrounding shadow
region can be calculated.
[0038] At 450, a determination can be made as to whether the number
of dark sub-regions in the areas surrounding the center region is
higher than a dark regions threshold. For example, the number of
dark regions can be compared to Stage_scene_dark_regions_threshold.
If it is greater, the flowchart 400 can advance to block 455. If
not, the flowchart 400 can advance to block 470.
[0039] Each of the blocks above can be used to determine the first
image is a stage scene image. However, while all of the
determinations can be made to determine whether the first image is
a stage scene image according a possible embodiment, not all
determinations are necessary according to other embodiments.
[0040] At 455, the frame luma for the automatic exposure control
can be adjusted for correct exposure of the center region of the
first image in response to determining the first image is a stage
scene. According to a possible embodiment, adjusting the frame luma
for the automatic exposure control can include decreasing a target
luma for proper exposure of the center region of the image.
According to another possible embodiment, adjusting the frame luma
for the automatic exposure control can include calculating the
frame luma only based on the center region of the image for proper
exposure of the center region of the image.
[0041] At 460, a second image of the scene can be captured based on
automatic exposure control using the adjusted frame luma. At 465,
the second image can be output. At 470, the flowchart 400 can
determine the image is not of a stage scene and automatic exposure
control can be performed without stage scene adjustments.
[0042] It should be understood that, notwithstanding the particular
steps as shown in the figures, a variety of additional or different
steps can be performed depending upon the embodiment, and one or
more of the particular steps can be rearranged, repeated or
eliminated entirely depending upon the embodiment. Also, some of
the steps performed can be repeated on an ongoing or continuous
basis simultaneously while other steps are performed. Furthermore,
different steps can be performed by different elements or in a
single element of the disclosed embodiments.
[0043] FIG. 5 is an example block diagram of an apparatus 500, such
as the apparatus 110, according to a possible embodiment. The
apparatus 500 can include a housing 510, a controller 520 within
the housing 510, audio input and output circuitry 530 coupled to
the controller 520, a display 540 coupled to the controller 520, a
transceiver 550 coupled to the controller 520, an antenna 555
coupled to the transceiver 550, a user interface 560 coupled to the
controller 520, a memory 570 coupled to the controller 520, and a
network interface 580 coupled to the controller 520. The apparatus
500 can also include a camera 590, such as the camera 120. The
apparatus 500 can perform the methods described in all the
embodiments.
[0044] The camera 590 can include a lens 592 and a sensor 594, such
as the lens 122 and the sensor 124. The display 540 can be a
viewfinder, a liquid crystal display (LCD), a light emitting diode
(LED) display, a plasma display, a projection display, a touch
screen, or any other device that displays information. The
transceiver 550 can include a transmitter and/or a receiver. The
audio input and output circuitry 530 can include a microphone, a
speaker, a transducer, or any other audio input and output
circuitry. The user interface 560 can include a keypad, a keyboard,
buttons, a touch pad, a joystick, a touch screen display, another
additional display, or any other device useful for providing an
interface between a user and an electronic device. The network
interface 580 can be a Universal Serial Bus (USB) port, an Ethernet
port, an infrared transmitter/receiver, an IEEE 1394 port, a WLAN
transceiver, or any other interface that can connect an apparatus
to a network, device, or computer and that can transmit and receive
data communication signals. The memory 570 can include a random
access memory, a read only memory, an optical memory, a flash
memory, a removable memory, a hard drive, a cache, or any other
memory that can be coupled to a device.
[0045] The apparatus 500 or the controller 520 may implement any
operating system, such as Microsoft Windows.RTM., UNIX.RTM., or
LINUX.RTM., Android.TM., or any other operating system. Apparatus
operation software may be written in any programming language, such
as C, C++, Java or Visual Basic, for example. Apparatus software
may also run on an application framework, such as, for example, a
Java.RTM. framework, a .NET.RTM. framework, or any other
application framework. The software and/or the operating system may
be stored in the memory 570 or elsewhere on the apparatus 500. The
apparatus 500 or the controller 520 may also use hardware to
implement disclosed operations. For example, the controller 520 may
be any programmable processor. Disclosed embodiments may also be
implemented on a general-purpose or a special purpose computer, a
programmed microprocessor or microprocessor, peripheral integrated
circuit elements, an application-specific integrated circuit or
other integrated circuits, hardware/electronic logic circuits, such
as a discrete element circuit, a programmable logic device, such as
a programmable logic array, field programmable gate-array, or the
like. In general, the controller 520 may be any controller or
processor device or devices capable of operating a device and
implementing the disclosed embodiments.
[0046] In operation, the sensor 594 can capture, via the lens 592,
a first image of a scene using a frame luma for automatic exposure
control. The controller 520 can calculate a brightness contrast
between a center region of the first image and areas surrounding
the center region of the first image. The controller 520 can
ascertain a brightness value for the entire first image. According
to a possible embodiment, the controller 520 can ascertain a
brightness value of the first image using an ambient light sensor
to evaluate ambient light brightness for the brightness value.
According to another possible embodiment, the controller 520 can
ascertain a brightness value using an automatic exposure control
process or any other way of ascertaining a brightness value of an
image. The controller 520 can determine the first image is a stage
scene image based on the brightness contrast being greater than a
stage scene contrast threshold and the brightness value for the
entire first image being less than a stage scene brightness value
threshold.
[0047] According to a possible embodiment, the controller 520 can
calculate a number of saturated sub-regions in the center region.
According to a possible implementation, the controller 520 can
calculate the number of saturated sub-regions in the center region
by determining whether each sub-region in the center region has a
brightness greater than a saturated sub-region brightness value
threshold and adding the number of sub-regions with a brightness
greater than the saturated sub-region brightness value threshold to
calculate the number of saturated sub-regions in the center region.
The controller 520 can determine the first image is a stage scene
image based on the brightness contrast being greater than a stage
scene contrast threshold, the brightness value for the entire first
image being less than a stage scene brightness value threshold, and
the number saturated sub-regions in the center region being higher
than a saturated regions threshold.
[0048] According to a possible embodiment, the controller 520 can
calculate a number of dark sub-regions in the areas surrounding the
center region. According to a possible implementation, the
controller 520 can calculate the dark sub-regions in the areas
surrounding the center region by determining whether each
sub-region in the dark areas has a brightness less than a dark
sub-region brightness value threshold and adding the number of
sub-regions with a brightness less than the dark sub-region
brightness value threshold to calculate the number of dark
sub-regions in the areas surrounding the center region. The
controller 520 can determine the first image is a stage scene image
based on the brightness contrast being greater than a stage scene
contrast threshold, the brightness for the entire first image value
being less than a stage scene brightness value threshold, and the
number of dark sub-regions in the areas surrounding the center
region being higher than a dark regions threshold.
[0049] The controller 520 can adjust the frame luma for the
automatic exposure control for correct exposure of the center
region of the first image in response to determining the first
image is a stage scene. According to a possible embodiment, the
controller 520 can adjust the frame luma for the automatic exposure
control by decreasing a target luma for proper exposure of the
center region of the image. According to another possible
embodiment, the controller 520 can adjust the frame luma for the
automatic exposure control by calculating the frame luma only based
on the center region of the image for proper exposure of the center
region of the image.
[0050] The sensor 594 can capture a second image of the scene based
on automatic exposure control using the adjusted frame luma. The
controller 520 can then output the second image via an output, such
as the display 540, the transceiver 550, the network interface 580,
an output to memory 570, or any other device for outputting an
image.
[0051] FIG. 6 is an example representation of an image 600 captured
without stage scene detection and compensation according to a
possible embodiment. Without the stage scene detection and
compensation of disclosed embodiments, the subject of the image 600
is overexposed and loses details that cannot be recovered.
[0052] FIG. 7 is an example representation of an image 700 captured
with stage scene detection and compensation according to a possible
embodiment. With the stage scene detection and compensation of
disclosed embodiments, the subject of the image 700 is properly
exposed.
[0053] The method of this disclosure can be implemented on a
programmed processor. However, the controllers, flowcharts, and
modules may also be implemented on a general purpose or special
purpose computer, a programmed microprocessor or microcontroller
and peripheral integrated circuit elements, an integrated circuit,
a hardware electronic or logic circuit such as a discrete element
circuit, a programmable logic device, or the like. In general, any
device on which resides a finite state machine capable of
implementing the flowcharts shown in the figures may be used to
implement the processor functions of this disclosure.
[0054] While this disclosure has been described with specific
embodiments thereof, it is evident that many alternatives,
modifications, and variations will be apparent to those skilled in
the art. For example, various components of the embodiments may be
interchanged, added, or substituted in the other embodiments. Also,
all of the elements of each figure are not necessary for operation
of the disclosed embodiments. For example, one of ordinary skill in
the art of the disclosed embodiments would be enabled to make and
use the teachings of the disclosure by simply employing the
elements of the independent claims. Accordingly, embodiments of the
disclosure as set forth herein are intended to be illustrative, not
limiting. Various changes may be made without departing from the
spirit and scope of the disclosure.
[0055] In this document, relational terms such as "first,"
"second," and the like may be used solely to distinguish one entity
or action from another entity or action without necessarily
requiring or implying any actual such relationship or order between
such entities or actions. The phrase "at least one of" followed by
a list is defined to mean one, some, or all, but not necessarily
all of, the elements in the list. The terms "comprises,"
"comprising," or any other variation thereof, are intended to cover
a non-exclusive inclusion, such that a process, method, article, or
apparatus that comprises a list of elements does not include only
those elements but may include other elements not expressly listed
or inherent to such process, method, article, or apparatus. An
element proceeded by "a," "an," or the like does not, without more
constraints, preclude the existence of additional identical
elements in the process, method, article, or apparatus that
comprises the element. Also, the term "another" is defined as at
least a second or more. The terms "including," "having," and the
like, as used herein, are defined as "comprising." Furthermore, the
background section is written as the inventor's own understanding
of the context of some embodiments at the time of filing and
includes the inventor's own recognition of any problems with
existing technologies and/or problems experienced in the inventor's
own work.
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