U.S. patent application number 15/944431 was filed with the patent office on 2018-08-09 for electronic device having dynamically controlled flashlight for image capturing and related control method.
This patent application is currently assigned to MEDIATEK INC.. The applicant listed for this patent is Mediatek Inc.. Invention is credited to Ding-Yun Chen, Cheng-Tsai Ho, Guo-Feng Wei.
Application Number | 20180227573 15/944431 |
Document ID | / |
Family ID | 56850179 |
Filed Date | 2018-08-09 |
United States Patent
Application |
20180227573 |
Kind Code |
A1 |
Chen; Ding-Yun ; et
al. |
August 9, 2018 |
ELECTRONIC DEVICE HAVING DYNAMICALLY CONTROLLED FLASHLIGHT FOR
IMAGE CAPTURING AND RELATED CONTROL METHOD
Abstract
A control method of an electronic device with an image capture
function is provided. The control method includes the following
steps: detecting a distance between the electronic device and at
least one subject in a scene to be captured to generate a distance
detection result; and utilizing a controller for referring to the
distance detection result to determine whether to turn on or turn
off a flashlight of the electronic device to capture the scene.
Inventors: |
Chen; Ding-Yun; (Taipei
City, TW) ; Wei; Guo-Feng; (Hsinchu City, TW)
; Ho; Cheng-Tsai; (Taichung City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mediatek Inc. |
Hsin-Chu City |
|
TW |
|
|
Assignee: |
MEDIATEK INC.
Hsin-Chu City
TW
|
Family ID: |
56850179 |
Appl. No.: |
15/944431 |
Filed: |
April 3, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14641431 |
Mar 8, 2015 |
9973743 |
|
|
15944431 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 5/23293 20130101;
H04N 5/23241 20130101; H04N 5/23218 20180801; H04N 5/232935
20180801; H04N 5/2354 20130101; H04N 5/232411 20180801; H04N
2013/0081 20130101; H04N 5/23219 20130101; H04N 13/239 20180501;
H04N 5/23216 20130101 |
International
Class: |
H04N 13/239 20060101
H04N013/239; H04N 5/232 20060101 H04N005/232; H04N 5/235 20060101
H04N005/235 |
Claims
1. A control method of an electronic device with an image capture
function, comprising: obtaining a plurality of images associated
with a scene, wherein the plurality of images includes a left eye
preview image and a right eye preview image that constitute a
stereoscopic image; detecting a distance between the electronic
device and at least one subject in the scene based on the plurality
of images; generating a distance detection result based on the
detected distance; and determining, via a controller, whether to
turn on or turn off a flashlight of the electronic device to
capture the scene based on the distance detection result.
2. The control method of claim 1, further comprising: determining a
brightness value associated with an environmental brightness of the
scene based on at least one of the plurality of images.
3. The control method of claim 1, wherein determining whether to
turn on or turn off the flashlight comprises: checking if a capture
trigger event occurs; and when it is detected that the capture
trigger event occurs, referring to the distance detection result to
turn on or turn off the flashlight to capture the scene.
4. The control method of claim 1, wherein detecting the distance
between the electronic device and the at least one subject in the
scene based on the plurality of images comprises: calculating
disparity information and/or depth information of at least a part
of the plurality of images to determine the distance.
5. The control method of claim 4, wherein said at least a part of
the plurality of images comprises a region-of-interest (ROI) of the
plurality of images.
6. The control method of claim 1, wherein when at least a part of
the plurality of images comprises a human face, detecting the
distance between the electronic device and the at least one subject
in the scene based on the plurality of images comprises: performing
face detection to generate a face detection result, and using the
face detection result to determine the distance.
7. The control method of claim 1, wherein determining whether to
turn on or turn off the flashlight comprises: determining whether
the distance is within a predetermined range according to the
distance detection result.
8. The control method of claim 7, wherein when it is determined
that the distance is within the predetermined range, determining,
via the controller, to turn on the flashlight, and when it is
determined that the distance is beyond the predetermined range,
determining, via the controller, to turn off the flashlight.
9. The control method of claim 7, wherein the predetermined range
is determined according to at least one of flashlight illumination
ability, an aperture size, lens parameters and optical sensitivity
of the electronic device.
10. The control method of claim 1, further comprising adjusting
light intensity of the flashlight after determining to turn on the
flashlight.
11. A control method of an electronic device with an image capture
function, comprising: obtaining a plurality of images associated
with a scene, wherein the plurality of images includes a pair of
images generated by dividing incident light based on phase
detection; detecting a distance between the electronic device and
at least one subject in the scene based on the plurality of images;
generating a distance detection result based on the detected
distance; and determining, via a controller, whether to turn on or
turn off a flashlight of the electronic device to capture the scene
based on the distance detection result.
12. The control method of claim 11, wherein determining whether to
turn on or turn off the flashlight comprises: checking if a capture
trigger event occurs; and when it is detected that the capture
trigger event occurs, referring to the distance detection result to
turn on or turn off the flashlight to capture the scene.
13. The control method of claim 11, wherein detecting the distance
between the electronic device and the at least one subject in the
scene based on the plurality of images comprises: calculating
disparity information and/or depth information of at least a part
of the plurality of images to determine the distance.
14. The control method of claim 11, wherein determining whether to
turn on or turn off the flashlight comprises: determining whether
the distance is within a predetermined range according to the
distance detection result.
15. The control method of claim 14, wherein when it is determined
that the distance is within the predetermined range, determining,
via the controller, to turn on the flashlight, and when it is
determined that the distance is beyond the predetermined range,
determining, via the controller, to turn off the flashlight.
16. The control method of claim 14, wherein the predetermined range
is determined according to at least one of flashlight illumination
ability, an aperture size, lens parameters and optical sensitivity
of the electronic device.
17. The control method of claim 11, further comprising adjusting
light intensity of the flashlight after determining to turn on the
flashlight.
18. An electronic device, comprising: a flashlight configured to
illuminate a scene to be captured; an image capturing system
configured to: obtain a plurality of images associated with a
scene, wherein the plurality of images includes a left eye preview
image and a right eye preview image that constitute a stereoscopic
image, or a pair of images generated by dividing incident light
based on phase detection; detect a distance between the electronic
device and at least one subject in the scene based on the plurality
of images; and generate a distance detection result based on the
detected distance; and a controller, coupled to the flashlight and
the image capturing system, the controller is configured to
determine whether to turn on or turn off the flashlight to capture
the scene based on the distance detection result.
19. The electronic device of claim 18, wherein an image capturing
module in the image capturing module is a stereo camera.
20. The electronic device of claim 18, wherein an image capturing
module in the image capturing module is a camera having color pixel
and phase detection pixel on image sensor.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation application of
U.S. patent application Ser. No. 14/641,431 filed on Mar. 8, 2015,
the entirety of which are incorporated by reference herein.
BACKGROUND
[0002] The disclosed embodiments of the present invention relate to
flashlight control, and more particularly, to a control method of
an electronic device having a dynamically controlled flashlight for
image capturing and a related electronic device with an image
capture function.
[0003] A flashlight of a conventional camera turns on automatically
to provide extra light whenever the light level is low for a good
exposure or when a main subject is backlit, wherein a flashlight
output is determined according to a brightness value (BV), an
aperture value, an exposure time (a shutter speed) and/or an ISO
speed of the camera. In addition, the flashlight turns on according
to a scene (e.g. a landscape scene or a portrait scene) analyzed by
the camera.
[0004] However, the flashlight has a limited effective flash output
distance. For example, an effective flash output distance of a
conventional camera phone is about two to three meters. Hence, even
though a flashlight of the camera phone turns on according to
alight level in the environment or an analyzed scene, the
flashlight cannot provide sufficient light for a subject when the
subject is far away from the camera phone. Specifically, an
exposure time is relatively short because an auto exposure (AE)
algorithm assumes that the flashlight can brighten the subject,
thus resulting in a relatively dark subject. Further, battery power
of the camera phone consumes while the flashlight has no help to
brighten the subject, resulting in wasting the battery power.
[0005] Thus, there is a need for a novel control mechanism to
dynamically control a flashlight of an image capturing
apparatus.
SUMMARY
[0006] In accordance with exemplary embodiments of the present
invention, a control method of an electronic device having a
dynamically controlled flashlight for image capturing and a related
electronic device with an image capture function are proposed to
solve the above-mentioned problems.
[0007] According to an embodiment of the present invention, an
exemplary control method of an electronic device with an image
capture function is disclosed. The exemplary control method
comprises the following steps: detecting a distance between the
electronic device and at least one subject in a scene to be
captured to generate a distance detection result; and utilizing a
controller for referring to the distance detection result to
determine whether to turn on or turn off a flashlight of the
electronic device to capture the scene.
[0008] According to an embodiment of the present invention, an
exemplary electronic device is disclosed. The exemplary electronic
device comprises a flashlight, an image capturing system and a
controller. The flashlight is arranged for illuminating a scene to
be captured. The image capturing system is arranged for capturing
the scene, and detecting a distance between the electronic device
and at least one subject in the scene to generate a distance
detection result. The controller is coupled to the flashlight and
the image capturing system, and is arranged for referring to the
distance detection result to determine whether to turn on or turn
off the flashlight.
[0009] The proposed electronic device with an image capture
function and related control method refer to a distance between the
electronic device and at least one subject to control a flashlight,
thereby effectively controlling activation timing of the
flashlight, reducing power consumption and improving image quality.
The proposed electronic device with the image capture function and
related control method can be employed in a variety of portable
electronic apparatuses.
[0010] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a flow chart illustrating an exemplary control
method of an electronic device with an image capture function
according to an embodiment of the present invention.
[0012] FIG. 2 is a block diagram illustrating an exemplary
electronic device according to an embodiment of the present
invention.
[0013] FIG. 3 is a diagram illustrating an image capturing
operation of an exemplary electronic device according to an
embodiment of the present invention.
[0014] FIG. 4, which is a diagram illustrating an image capturing
operation of the camera phone shown in FIG. 3.
[0015] FIG. 5 is a flow chart illustrating an exemplary control
method of an electronic device with an image capture function
according to another embodiment of the present invention.
[0016] FIG. 6 is a diagram illustrating a shooting distance between
the camera phone and the subject shown in FIG. 3/FIG. 4 and a
predetermined range associated therewith according to an embodiment
of the present invention.
[0017] FIG. 7 is a flow chart illustrating an exemplary control
method of an electronic device with an image capture function
according to another embodiment of the present invention.
[0018] FIG. 8 is a flowchart illustrating an exemplary control
method of an electronic device with an image capture function
according to another embodiment of the present invention.
[0019] FIG. 9 is a block diagram illustrating an exemplary
electronic device according to another embodiment of the present
invention.
DETAILED DESCRIPTION
[0020] Certain terms are used throughout the description and
following claims to refer to particular components. As one skilled
in the art will appreciate, manufacturers may refer to a component
by different names. This document does not intend to distinguish
between components that differ in name but not function. In the
following description and in the claims, the terms "include" and
"comprise" are used in an open-ended fashion, and thus should be
interpreted to mean "include, but not limited to . . . ". Also, the
term "coupled" is intended to mean either an indirect or direct
electrical connection. Accordingly, if one device is electrically
connected to another device, that connection may be through a
direct electrical connection, or through an indirect electrical
connection via other devices and connections.
[0021] In order to effectively control activation timing of a
flashlight, the proposed flashlight control mechanism may determine
operations of the flashlight according to a distance between an
electronic device and a subject to be captured/photographed. FIG. 1
is a flow chart illustrating an exemplary control method of an
electronic device with an image capture function according to an
embodiment of the present invention. The exemplary control method
may be summarized as below.
[0022] Step 100: Start.
[0023] Step 110: Detect a distance between the electronic device
and at least one subject in a scene to be captured to generate a
distance detection result.
[0024] Step 120: Utilize a controller for referring to the distance
detection result to determine whether to turn on or turn off a
flashlight of the electronic device to capture the scene.
[0025] In step 110, the distance detection result may be generated
in various manners. By way of example but not limitation, the
distance detection result may be obtained by analyzing image(s) of
the at least one subject, wherein the distance detection result may
be depth information, disparity information and/or geometric
characteristics of the at least one subject. In another example, a
specific signal (e.g. an infrared light signal or an audio signal)
may be emitted to the at least one subject first, and then the
distance detection result may be generated according to a reflected
signal reflected from the at least one subject in response to the
specific signal.
[0026] In step 120, when the electronic device receives a capture
trigger event (e.g. a user presses a shutter button of the
electronic device), the controller may refer to the distance
detection result to turn on or turn off the flashlight to capture
the scene. In this embodiment, the distance detection (step 110)
and the determination of flashlight activation (step 120) may be
performed before the electronic device receives the capture trigger
event, which means that the distance detection may be performed in
real time to determine whether to turn on or turn off the
flashlight. This is not meant to be a limitation of the present
invention. In one implementation, the distance detection and the
determination of flashlight activation may be performed after the
electronic device receives the capture trigger event.
[0027] In practice, the controller may be implemented in the
electronic device so that the electronic device may
determine/control operations of the flashlight according to the
distance between the electronic device and the at least one
subject. Please refer to FIG. 2 in conjunction with FIG. 1. FIG. 2
is a block diagram illustrating an exemplary electronic device
according to an embodiment of the present invention. The electronic
device 200 shown in FIG. 2 may employ the control method shown in
FIG. 1 to control/determine operations of a flashlight. The
electronic device 200 may be implemented by a portable electronic
apparatus (e.g. a camera or a camera phone), and may include, but
is not limited to, a flashlight 210, an image capturing system 220
and a controller 230. The flashlight 210 is arranged for
illuminating a scene SC to be captured, and the image capturing
system 220 is arranged for capturing the scene SC. The controller
230 is coupled to the flashlight 210 and the image capturing system
220, and is used to control operations of the flashlight 210 and
the image capturing system 220.
[0028] Firstly, as shown in step 110, the image capturing system
220 may detect a distance DS between the electronic device 200 and
at least one subject (e.g. a subject SB) in the scene SC to
generate a distance detection result DR1. In this embodiment, the
distance detection result DR1 may be obtained by analyzing image(s)
of the at least one subject. By way of example but not limitation,
the image capturing system 220 may include an image capturing
module 224 (e.g. a camera module) and a processing circuit 226. The
image capturing module 224 may be arranged to capture at least one
preview image of the at least one subject. By way of example but
not limitation, the image capturing module 224 may include
sensor(s), lens(es) and/or image processor(s) (not shown in FIG. 2)
so as to perform image capture. The processing circuit 226 is
coupled to the image capturing module 224, and may be arranged to
generate the distance detection result DR1 according to the at
least one preview image. In one implementation, the processing
circuit 226 may analyze/calculate image information (e.g. depth
information, disparity information and/or face information) of at
least one part of the at least one preview image to generate
distance detection result DR1.
[0029] Next, as shown in step 120, the controller 230 may refer to
the distance detection result DR1 to determine whether to turn on
or turn off the flashlight 210 to capture the scene SC. By way of
example but not limitation, when the distance detection result DR1
indicates that the distance DS is within a predetermined range, the
activation of the flashlight 210 may provide enough illumination to
the at least one subject. Hence, the controller 230 may determine
to turn on the flashlight 210 (e.g. turning on the flashlight 210
while capturing the scene SC). When the distance detection result
DR1 indicates that the distance DS is not within (or beyond) the
predetermined range, the controller 230 may determine to turn off
the flashlight 210 (e.g. keeping the flashlight 210 turned off
while capturing the scene SC) because the flashlight 210 may not
provide adequate illumination. When the electronic device 200
receives a capture trigger event (e.g. a user presses a shutter
button) to capture the scene SC, the controller 230 may turn on or
turn off the flashlight 210 accordingly, and control the image
capturing system 220 to capture the scene SC.
[0030] For better understanding of the present invention, an
exemplary electronic device implemented by a camera phone is given
in the following for further description of the proposed flashlight
control mechanism. However, a person skilled in the art should
understand that the proposed flashlight control mechanism may be
employed in other types of electronic devices. Please refer to FIG.
3, which is a diagram illustrating an image capturing operation of
an exemplary electronic device according to an embodiment of the
present invention. In this embodiment, the proposed electronic
device may be implemented by a camera phone 300, wherein the
architecture of the camera phone 300 is based on the architecture
of the electronic device 200 shown in FIG. 2. The camera phone 300
may include, but is not limited to, a flashlight 310, an image
capturing system (not shown in FIG. 3), a controller (not shown in
FIG. 3) and a display screen 340, wherein the flashlight 310 is
disposed on a first side FS (e.g. a rear side) of the phone camera
phone 300, and the display screen 340 is disposed on a second side
RS (e.g. a front side) of the phone camera phone 300 in this
embodiment. The image capturing system may include an image
capturing module 324 and a processing circuit (not shown in FIG.
3), and the image capturing module 324 may be implemented by a
stereo camera (including dual cameras DL1 and DL2). Please note
that the flashlight 310, the image capturing system and the
controller may be implemented by the flashlight 210, the image
capturing system 220 and the controller 230 shown in FIG. 2
respectively. As FIG. 3 illustrates a physical appearance of the
camera phone 300, the image capturing system, the controller and
the processing circuit included in the camera phone 300 are not
shown in FIG. 3 for brevity.
[0031] In this embodiment, the camera phone 300 may operate in an
auto flash mode. In other words, the camera phone 300 may determine
whether to turn on the flashlight 310 according to environment
brightness. For example, the image capturing system may further
determine whether the environment brightness is less than a
threshold before performing distance detection. In this embodiment,
the camera phone 300 may utilize the image capturing module 324 to
capture a preview image of the scene SC.sub.P1. The processing
circuit may calculate at least one of a brightness value, an
aperture value, an exposure time and an ISO speed, and accordingly
determine whether the environment brightness is less than a
threshold. When it is determined that the environment brightness is
less than the threshold (i.e. the environment brightness is
insufficient), the camera phone 300 (the image capturing system)
may detect a distance to a subject SB.sub.P (i.e. a distance DS1
between the camera phone 300 and subject SB.sub.P) to thereby
determine whether to turn on the flashlight 310. When it is
determined that the environment brightness is greater than or equal
to the threshold, it will be unnecessary to turn on the flashlight
310 due to the sufficient environment brightness.
[0032] In a case where it is determined that the environment
brightness is less than the threshold, the camera phone 300 may
further utilize the image capturing module 324 to capture a stereo
image IMG.sub.P1 (including a right eye preview image captured by
the camera DL1 and a left eye preview image captured by the camera
DL2), and the processing circuit may detect the distance between
the camera phone 300 and subject SB.sub.P according to the stereo
image IMG.sub.P1 to thereby generate a distance detection result.
By way of example but not limitation, the processing circuit may
calculate depth information (and/or disparity information) of at
least one part of the stereo image IMG.sub.P1 to generate the
distance detection result, wherein the distance detection result
may indicate the distance DS1 between the camera phone 300 and
subject SB.sub.P (as shown in the upper portion of FIG. 3).
[0033] Next, the controller of the camera phone 300 may determine
whether the distance DS1 is within a predetermined range (e.g. an
effective flash output distance) according to the distance
detection result. In this embodiment, the camera phone 300 is close
enough to the subject SB.sub.P, the distance DS1 is within the
predetermined range. This means that the activation of the
flashlight 310 may provide sufficient illumination to the scene
SC.sub.P1 (the subject SB.sub.P). The controller may determine to
turn on the flashlight 310 to capture the scene SC.sub.P1, and the
image quality can be improved accordingly. When a user
presses/touches a shutter button VS displayed on the display screen
340 (as shown in the lower portion of FIG. 3), the controller may
turn on the flashlight 310 to capture the scene SC.sub.P1 a stereo
image IMG.sub.S1). As shown in FIG. 3, the image capturing system
324 receives more illumination when capturing the stereo image
IMG.sub.S1 (an actually captured image) than when capturing the
stereo image IMG.sub.P1 (a preview image).
[0034] When the camera phone 300 is distant from the subject
SB.sub.P, the flashlight 310 may not provide sufficient
illumination. Hence, the controller may determine to turnoff the
flashlight 310. Please refer to FIG. 4, which is a diagram
illustrating an image capturing operation of the camera phone 300
shown in FIG. 3. In this embodiment, a distance DS2 between the
subject SB.sub.P and the camera phone 300 is not within the
predetermined range. Hence, when the user presses/touches the
shutter button VS, the controller will not turn on the flashlight
310, thus avoiding unnecessary power consumption. As shown in FIG.
4, each of a stereo image IMG.sub.2 (including a left eye preview
image and a right eye preview image) and a stereo image IMG.sub.S2
(an actually captured image) is captured without turning on the
flashlight 310.
[0035] The image capturing operations shown in FIG. 3 and FIG. 4
may be summarized in a flowchart shown in FIG. 5. FIG. 5 is a flow
chart illustrating an exemplary control method of an electronic
device with an image capture function according to another
embodiment of the present invention. The control method shown in
FIG. 5 is based on the control method shown in FIG. 1 and therefore
may be employed in a variety of electronic devices. Step 110 shown
in FIG. 1 may be implemented by steps 512 and 514 shown in FIG. 5,
and step 120 shown in FIG. 1 may be implemented by steps 522-527
shown in FIG. 5. Provided that the result is substantially the
same, the steps are not required to be executed in the exact order
shown in FIG. 5. The control method shown in FIG. 5 may be
summarized as below.
[0036] Step 500: Start.
[0037] Step 502: Capture a first preview image of a scene to be
captured (e.g. the scene SC.sub.P1 shown in FIG. 3 or the scene
SC.sub.P2 shown in FIG. 4).
[0038] Step 504: Determine whether environment brightness is less
than a threshold according to the first preview image. If yes,
proceed to step 512; otherwise, go to step 525.
[0039] Step 512: Capture a plurality of second preview images (e.g.
a left eye preview image and a right eye preview image) of the
scene to be captured.
[0040] Step 514: Detect a distance between the electronic device
(e.g. the camera phone 300) and at least one subject (e.g. the
subject SB.sub.P shown in FIG. 3/FIG. 4) in the scene to generate a
distance detection result.
[0041] Step 522: Determine whether the distance is within a
predetermined range according to the distance detection result. If
yes, go to step 524; otherwise, go to step 525.
[0042] Step 524: Check if a capture trigger event (e.g. the user
touches the shutter button VS shown in FIG. 3/FIG. 4) occurs. If
yes, proceed to step 526; otherwise, return to step 502.
[0043] Step 525: Check if a capture trigger event occurs. If yes,
proceed to step 527; otherwise, return to step 502.
[0044] Step 526: Turn on a flashlight (e.g. the flashlight 310
shown in FIG. 3/FIG. 4) and capture the scene.
[0045] Step 527: Turn off the flashlight and capture the scene.
[0046] To facilitate understanding, steps of the control method
shown in FIG. 5 are described below with reference to FIG. 3 and
FIG. 4.
[0047] In step 504, the processing circuit of the camera phone 300
may calculate at least one shooting parameter (e.g. a brightness
value, an aperture value, an exposure time and an ISO speed)
according to the first preview image, and compare the at least on
shooting parameter with at least one predetermined value included
in the threshold in order to determine if the environment
brightness is insufficient. In other words, the calculated at least
one shooting parameter may represent the environment brightness.
Please note that the threshold (the at least one predetermined
value) may be set in advance or adjusted dynamically. For example,
the processing circuit may adjust/select the threshold according to
a current scene mode and/or a current camera setting.
[0048] In step 512 and step 514, the obtained distance detection
result may indicate the distance between the camera phone 300 and
the subject SB.sub.P. Please note that the number of second preview
images used for detecting a shooting distance is not limited to
two. Additionally, the distance detection may be implemented in
different manners in response to different numbers/types of second
preview images. Further description is described below.
[0049] In one implementation, the image capturing module 324 may
capture more than two second preview images (e.g. a plurality of
stereo images), and the processing circuit may calculate average
depth information and/or disparity information of the stereo images
to generate the distance detection result. In another
implementation, the second preview images captured by the image
capturing module 324 are not limited to a left eye preview image
and a right eye preview image (i.e. two color images). For example,
the camera DL1 may be implemented by a color camera, and the camera
DL2 may be implemented by a depth camera. Hence, the stereo image
IMG.sub.P1/IMG.sub.P2 captured by the image capturing module 324
may be synthesized by a color image captured by the camera DL1 and
a depth image captured by the camera DL2, and the processing
circuit may calculate depth information and/or disparity
information of the depth image to generate the distance detection
result.
[0050] In yet another implementation, the second preview images may
be captured by a plurality of cameras having different resolutions
and/or image sensing structures (e.g. a lens structure, a sensor
structure and/or a color filter structure). For example, the image
capturing module 324 may include a first camera having a first
resolution (e.g. the camera DL1) and a second camera having a
second resolution from the first resolution (e.g. the camera DL2),
and the processing circuit may calculate depth information and/or
disparity information according to a first preview image captured
by the first camera and a second preview image captured by the
second camera. In another example, the image capturing module 324
may include a first camera having a first image sensing structure
(e.g. the camera DL1) and a second camera having a second image
sensing structure from the first image sensing structure (e.g. the
camera DL2), and the processing circuit may calculate depth
information and/or disparity information according to a first
preview image captured by the first camera and a second preview
image captured by the second camera.
[0051] In still another implementation, the image capturing module
324 may include only a single camera, wherein the single camera
captures the second preview images at different times. For example,
the single camera may capture the second preview images of the
scene SC.sub.P at different positions, and the processing circuit
may calculate depth information and/or disparity information of the
second preview images. In another example, the single camera may
capture the second preview images under different camera settings
(e.g. auto white balance, auto focus and auto exposure) to thereby
calculate depth information and/or disparity information of the
second preview images. In still another example, the single camera
may capture the second preview images with different focus
settings, and analyze the second preview images to obtain depth
information and/or disparity information thereof.
[0052] In an alternative design, the image capturing module 324 may
capture a single second preview image only, and the processing
circuit may generate the distance detection result according to the
single second preview image. For example, the image capturing
module 324 may include a camera, wherein an image sensor of the
camera includes a color pixel and a depth pixel. Hence, the
processing circuit may calculate depth/disparity information of the
captured second preview image. In another example, the image
capturing module 324 may include a camera, wherein an image sensor
of the camera includes a color pixel and a phase detection pixel.
When the camera captures a preview image of the subject SB.sub.P,
incident light may be divided into a pair of images, and the phase
detection pixel may capture the pair of images. The processing
circuit may detect the distance between the subject SB.sub.P and
the camera phone 300 according to the pair of images so as to
generate the distance detection result. As a person skilled in the
art should understand image sensing principles of the depth pixel
and the phase detection pixel, further description is omitted here
for brevity.
[0053] In view of the above, the processing circuit may generate
the distance detection result according to at least one second
preview image captured by the image capturing module 324.
[0054] Additionally, in step 514, the processing circuit may
calculate depth information and/or disparity information of at
least one part of at least one second preview image captured by the
image capturing module 324 to generate the distance detection
result. For example, the processing circuit may calculate depth
information and/or disparity information of a whole second preview
image, a downsized second preview image or a region-of-interest
(ROI) of a second preview image. The ROI may be, but is not limited
to, a subject region, a center of the second preview image (a
left/right eye image), a high texture region of the second preview
image, a human face region or a touch focus region.
[0055] Further, in a case where the processing circuit calculates
depth information and/or disparity information to generate the
distance detection result, the processing circuit may perform
statistical operations upon the depth/disparity information of the
ROI to generate the distance detection result. For example, an
average, a maximum, an average of several maxima, a histogram or a
statistics value obtained from the depth/disparity information may
be used as the distance detection result.
[0056] It should be noted that, in a case where the at least one
subject (e.g. the subject SB.sub.P) is human subject or includes a
human face, the processing circuit may perform face detection upon
at least one second preview image (captured by the image capturing
module 324) to generate a face detection result, wherein the face
detection result may be used as the distance detection result. In
one implementation, the processing circuit may perform the face
detection upon a single second preview image to generate the face
detection result, wherein the face detection result may indicate a
region/position, a size and/or an age of the human face. Next, the
controller may determine the distance between the camera phone 300
and the subject SB.sub.P according to the face detection result
(e.g. at least one of the size and the age of the human face).
Please note that, when the processing circuit detects that the
second preview image includes a plurality of human faces (i.e. a
plurality of subjects), the processing circuit may use information
associated with one of the human faces (e.g. a human face of
maximum size) as the face detection result, or average information
associated with the human faces (e.g. averaging human sizes) to
generate the face detection result.
[0057] In another implementation, the processing circuit may
perform the face detection upon the second preview images to
generate the face detection result. For example, the processing
circuit may perform the face detection upon each of the second
preview images to generate the face detection result. In another
example, the processing circuit may perform the face detection upon
one of the second preview images, predict size(s) and/or
position(s) of human face(s) in other second preview images, and
generate the face detection result accordingly. Next, the
controller circuit may determine the distance between the camera
phone 300 and the subject SB.sub.p according to the face detection
result.
[0058] In an alternative design, after a human face region is
detected, the processing circuit may calculate depth information
and/or disparity information associated with the human face region
to generate the distance detection result.
[0059] In step 522, after completing the distance determination,
the electronic device may generate a message to inform the user
whether the distance is within the predetermined range. For
example, in the embodiment shown in FIG. 3, when the controller
determines that the distance DS1 is within the predetermined range,
the display screen 340 may display a message "F.sub.ON". Hence, the
user may know that the scene SC.sub.P1 will be captured under a
condition where the flashlight 310 turns on. In the embodiment
shown in FIG. 4, when the controller determines that the distance
DS2 is beyond the predetermined range, the display screen 340 may
display a message "F.sub.OFF". Hence, the user may know that the
scene SC.sub.P2 will be captured under a condition where the
flashlight 310 turns off.
[0060] The aforementioned predetermined range may be determined
according to flashlight intensity and/or optical characteristics of
the electronic device. For example, the predetermined range may be
determined/calibrated in advance according to at least one of
flashlight illumination ability, an aperture size, lens parameters
and optical sensitivity of the electronic device.
[0061] Additionally, in step 522, when a shooting distance (the
distance between the camera phone 300 and the subject SB.sub.P) is
beyond the predetermined range, it may imply that the shooting
distance is too long or too short. Please refer to FIG. 6, which is
a diagram illustrating a shooting distance between the camera phone
300 and the subject SB.sub.P shown in FIG. 3/FIG. 4 and a
predetermined range associated therewith according to an embodiment
of the present invention. In this embodiment, the predetermined
range RG.sub.1 may be defined by a first boundary (a distance
D.sub.1) and a second boundary (a distance D.sub.2), wherein the
first boundary is greater than the second boundary. The first
boundary may be used to determine whether the shooting distance
D.sub.SH is too long (greater than the distance D.sub.1), and the
second boundary may be used to determine whether the shooting
distance D.sub.SH is too short (less than the distance D.sub.2). In
a case where the shooting distance D.sub.SH is too long (e.g. the
subject SB.sub.P located at a distance D.sub.A from the camera
phone 300), the flashlight 310 may not provide enough illumination
to a scene to be captured (the subject SB.sub.P). Hence, the
controller may turn off the flashlight 310 (or keep the flashlight
310 turned off), and the image capturing module 324 may use a
flash-off setting (e.g. an adequate ISO speed and/or exposure time)
to avoid underexposure. In a case where the shooting distance
D.sub.SH is too short (e.g. the subject SB.sub.P located at a
distance D.sub.B from the camera phone 300), the activation of the
flashlight 310 may result in overexposure. Hence, the controller
may turn off the flashlight 310 (or keep the flashlight 310 turned
off), and the image capturing module 324 may use a flash-off
setting to avoid overexposure.
[0062] In step 524 and step 525, when the capture trigger event
occurs, the image capturing module 324 may capture the scene (e.g.
the scene SC.sub.P1/SC.sub.P2). In one implementation, the capture
trigger event may be triggered by the user (e.g. touching the
shutter button VS). In another implementation, the capture trigger
event may be generated internally by the camera phone 300. For
example, in a case where the camera phone 300 operates in a flash
on mode and the user holing the camera phone 300 is distant from
the scene to be captured, the controller may generate a hint
displayed on the screen 340 so as to suggest the user move toward
the scene. When the user moves toward the scene such that the
distance between the camera phone 300 and the scene is within than
the predetermined range, the controller may trigger the image
capture event. After the scene is captured, the camera phone 300
may return to a camera preview mode (return to step 502). The
camera phone 300 may also return to the camera preview mode if no
capture trigger event occurs.
[0063] Next, in step 526, the controller may turn on the flashlight
310, and the image capturing module 324 may use a flash-on setting
(e.g. an adequate ISO speed and/or exposure time) to capture the
scene (e.g. capturing the stereo image shown IMG.sub.S1 in FIG. 3).
In step 527, the controller may turn off the flashlight 310, and
the image capturing module 324 may use a flash-off setting to
capture the scene (e.g. capturing the stereo image IMG.sub.S2 shown
in FIG. 4). Although an actually captured image in the embodiment
shown in FIG. 3/FIG. 4 is a stereo image, this is for illustrative
purposes only and is not meant to be a limitation of the present
invention. In an alternative, it is possible to capture an image
from only a single camera (e.g. the camera DL2 used for capturing a
right eye image) as the actually captured image in step
526/527.
[0064] It should be noted that, after the controller turns on the
flashlight 310 according to the distance detection result (step
526), the controller may further refer to the distance detection
result to adjust light intensity of the flashlight 310 to capture
the scene (e.g. the scene SC.sub.P1/SC.sub.P2). In one
implementation, when the shooting distance increases (still within
the predetermined range), the controller may increase the light
intensity of the flashlight 310 to provide sufficient illumination.
In another implementation, when the shooting distance decreases
(still within the predetermined range), the controller may decrease
the light intensity of the flashlight 310 to avoid overexposure. In
view of this, the proposed flashlight control mechanism may refer
to the distance detection result directly rather perform a
pre-flash operation in advance to adjust light intensity of the
flashlight.
[0065] Additionally, before the scene is captured, a variation of
the shooting distance near a boundary of the predetermined range
(e.g. the distance D.sub.1/D.sub.2 shown in FIG. 6) may affect the
determination of the flashlight activation. For example, in step
522, the display screen 340 may display the message "F.sub.ON" or
"F.sub.OFF" to show the determination of the flashlight activation.
When the shooting distance moves back and forth across the boundary
of the predetermined range, the display screen 340 may display the
messages "F.sub.ON" and "F.sub.OFF" alternately. Hence, after
referring to the distance detection result to determine to switch
the flashlight 310 from one of an ON state and an OFF state to the
other of the ON state and the OFF, the controller may further
adjust the predetermined range to facilitate the determination of
the flashlight activation. Please refer to FIG. 6 again. As shown
in FIG. 6, the shooting distance D.sub.SH is D.sub.A initially, and
the corresponding predetermined range is labeled RG.sub.1. When
shooting distance D.sub.SH is shortened to D.sub.C (e.g. the
subject SB.sub.P moves toward the camera phone 300, and/or the
camera phone 300 moves toward the subject SB.sub.P) and falls
within the predetermined range RG.sub.1, the controller may
determine to turn on the flashlight 310 to capture the scene, and
adjust the first boundary from the distance D.sub.1 to a distance
D.sub.11. Hence, even though the shooting distance D.sub.SH varies
slightly (e.g. the subject SB.sub.P moves slightly from the
distance D.sub.C to a distance D.sub.C'), the controller may
determine to turn on the flashlight 310 to capture the scene.
[0066] Next, when shooting distance D.sub.SH is lengthened from
D.sub.C' to D.sub.D (e.g. the subject SB.sub.P moves away from the
camera phone 300, and/or the camera phone 300 moves away from the
subject SB.sub.P) and falls beyond the predetermined range defined
by the distances D.sub.2 and D.sub.11, the controller may determine
to turn off the flashlight 310 to capture the scene, and adjust the
first boundary from the distance D.sub.11 to a distance D.sub.12.
Hence, even though the shooting distance D.sub.SH varies slightly
(e.g. the subject SB.sub.P moves slightly from the distance D.sub.D
to a distance D.sub.C'), the controller may determine to turn off
the flashlight 310 to capture the scene.
[0067] For illustrative purposes, the predetermined range is
adjusted by changing the first boundary (used for determining
whether the shooting distance D.sub.SH is too long). However, this
is not meant to be a limitation of the present invention. After
reading the above paragraphs directed to FIG. 6, a person skilled
in the art should understand that the predetermined range may be
adjusted by changing the second boundary (used for determining
whether the shooting distance D.sub.SH is too short). Similar
descriptions are not repeated for the sake of brevity.
[0068] The determination of the environment brightness as described
in step 502 and step 504 is for illustrative purposes only, and is
not meant to be a limitation of the present invention. For example,
the aforementioned second preview image(s) may be used to determine
the environment brightness. Please refer to FIG. 7, which is a flow
chart illustrating an exemplary control method of an electronic
device with an image capture function according to another
embodiment of the present invention. The control method shown in
FIG. 7 is based on the control method shown in FIG. 5, wherein the
main difference is that the control method shown in FIG. 7 may
determine the environment brightness according to preview images(s)
used for detecting the shooting distance. The control method shown
in FIG. 7 may be summarized as below.
[0069] Step 700: Start.
[0070] Step 712: Capture a plurality of preview images (e.g. the
second preview images as described in step 512) of a scene to be
captured.
[0071] Step 704: Determine whether environment brightness is less
than a threshold according to at least one of the preview images.
If yes, proceed to step 714; otherwise, go to step 725.
[0072] Step 714: Detect a distance between the electronic device
and at least one subject in the scene to generate a distance
detection result.
[0073] Step 722: Determine whether the distance is within a
predetermined range according to the distance detection result. If
yes, go to step 724; otherwise, go to step 725.
[0074] Step 724: Check if a capture trigger event occurs. If yes,
proceed to step 726; otherwise, return to step 712.
[0075] Step 725: Check if a capture trigger event occurs. If yes,
proceed to step 727; otherwise, return to step 712.
[0076] Step 726: Turn on a flashlight and capture the scene.
[0077] Step 727: Turn off the flashlight and capture the scene.
[0078] Step 712 may be implemented by step 512 shown in FIG. 5. In
step 704, the processing circuit of the camera phone 300 shown in
FIG. 3/FIG. 4 may determine the environment brightness according to
only one of the preview images (step 504 shown in FIG. 5). In one
implementation, the processing circuit may perform brightness
detection according to the preview images so as to generate a
plurality of brightness detection results respectively (e.g.
calculate at least one shooting parameter of each preview image),
and compare an average of the brightness detection results with the
threshold to thereby determine whether the environment brightness
is insufficient. In this embodiment, the operations in steps 714,
722, 724, 725, 726 and 727 may be similar/identical to those in
steps 514, 522, 524, 525, 526 and 527 shown in FIG. 5 respectively.
However, this is not meant to be a limitation of the present
invention. As a person skilled in the art should understand the
operation of each step of the control method shown in FIG. 7 after
reading the above paragraphs directed to FIGS. 1-6, further
description is omitted here for brevity.
[0079] In an alternative design, the proposed flashlight control
mechanism may utilize an ambient light sensor to determine the
environment brightness. In another alternative design, it is
possible to omit the step of determining the environment
brightness. Please refer to FIG. 8, which is a flow chart
illustrating an exemplary control method of an electronic device
with an image capture function according to another embodiment of
the present invention. The control method shown in FIG. 8 is based
on the control method shown in FIG. 7, wherein the operations in
steps 812, 814, 822, 824, 825, 826 and 827 shown in FIG. 8 may be
similar/identical to those in steps 712, 714, 722, 724, 725, 726
and 727 shown in FIG. 7 respectively, and the main difference is
that the step of determining the environment brightness maybe
omitted in the control method shown in FIG. 8. For example, when
feeling that a preview image of a scene displayed on the display
screen 340 shown in FIG. 3 is dark, the user may activate a flash
on function of the camera phone 300 (i.e. the camera phone 300
operates in a flash on mode), wherein the camera phone 300
operating in the flash on mode may employ the control method shown
in FIG. 8 to control the flashlight 310. It should be noted that
the control method shown in FIG. 8 may be employed in an auto flash
mode, wherein the auto flash mode means that the phone camera 300
may turn on the flashlight 310 automatically according to the
shooting distance. As a person skilled in the art should understand
the operation of each step of the control method shown in FIG. 8
after reading the above paragraphs directed to FIGS. 1-7, further
description is omitted here for brevity.
[0080] In view of the above, the proposed control method of an
electronic device with an image capture function may effectively
control activation timing of the flashlight so as to provide
flexible flashlight control mechanism. Additionally, the proposed
control method may be employed in a variety of electronic devices.
Please refer to FIG. 9, which is a block diagram illustrating an
exemplary electronic device according to another embodiment of the
present invention. The architecture of the electronic device 900
shown in FIG. 9 is based on the architecture of the electronic
device 200 shown in FIG. 2, wherein the main difference is that the
electronic device 900 may generate a distance detection result DR2
according to a reflected signal reflected from the subject SBP. In
this embodiment, the electronic device 900 may include, but is not
limited to, the flashlight 210 and the controller 230 shown in FIG.
2 and an image capturing system 920. The image capturing system 920
may detect the distance DS between the electronic device 900 and at
least one subject (e.g. the subject SB) in the scene SC to be
captured to generate the distance detection result DR2. The image
capturing system 920 may include a light emitter (e.g. an infrared
light emitter) 924 and a processing circuit 926. The light emitter
924 is coupled to the controller 230, and is activated by the
controller 230 to emit a light signal L1 to the at least one
subject (e.g. the subject SB). When the light emitter 924 is
activated, the processing circuit 926 may receive a light signal L2
reflected from the at least one subject in response to the first
light signal L1, and generate the distance detection result DR2
according to the light signal L2, wherein the distance detection
result DR2 may indicate the distance DS between the electronic
device 900 and the at least one subject. Next, the controller 230
may refer to the distance detection result DR2 to determine whether
to turn on or turn off the flashlight 210 to capture the scene SC.
As a personal skilled in the art should understand the operations
of distance measurement using signal reflection, further
description is omitted here for brevity,
[0081] In one implementation, the electronic device 900 may further
include an image capturing module (e.g. a camera module; not shown
in FIG. 9), wherein the image capturing module may be controlled by
the controller 230 to perform image capturing, and may be arranged
for detecting a shooting distance (e.g. the image capturing module
224 shown in FIG. 2). After reading the above paragraphs directed
to FIGS. 1-8, a person skilled in the art should understand that
the electronic device 900 may employ the control methods shown in
FIG. 1, FIG. 5, FIG. 6 and/or FIG. 7 to control/determine the
operation of the flashlight 210. Further description is omitted
here for brevity.
[0082] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *