CN109215571B - Image processing method and device - Google Patents

Image processing method and device Download PDF

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CN109215571B
CN109215571B CN201811249126.7A CN201811249126A CN109215571B CN 109215571 B CN109215571 B CN 109215571B CN 201811249126 A CN201811249126 A CN 201811249126A CN 109215571 B CN109215571 B CN 109215571B
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pixel
luminance
input frame
value
frame image
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CN109215571A (en
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李福文
孔玮曼
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Granfi Smart Technology Beijing Co Ltd
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Shanghai Zhaoxin Integrated Circuit Co Ltd
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness

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  • Physics & Mathematics (AREA)
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  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

The invention provides an image processing method and device for realizing automatic current limiting, wherein the method comprises the following steps: reducing the overall brightness of the input frame image according to the global brightness value of the input frame image; increasing the individual brightness of each pixel in the input frame image according to the absolute difference between the characteristic brightness value of each pixel and the global brightness value of the input frame image; and increasing the individual luminance of each pixel according to the characteristic luminance value of each pixel and the global luminance value of the input frame image.

Description

Image processing method and device
Technical Field
The present invention relates to an image processing method and apparatus, and more particularly, to an image processing method and apparatus for implementing Automatic Current Limiting (ACL).
Background
The electronic device generally includes a display and a display driving device, and the display driving device can control the brightness of the image displayed by the display by controlling the magnitude of the current. The overall brightness (overall brightness refers to the visually perceived brightness) level of many displays can be adjusted. For example, the display may have settings for manually increasing or decreasing brightness by the user. The display may also have a setting that automatically adjusts the brightness according to ambient light.
For an oled (organic Light Emitting diode) display, an Automatic Current Limiting (ACL) method and apparatus (e.g., an ACL chip or an ACL module) are usually used by a display driving apparatus to reduce the brightness of an input frame image, so as to achieve the purpose of reducing the power consumption of the display and prolonging the service life of the display.
Reducing the brightness of an input frame image as referred to in the prior art generally refers to reducing the average brightness of the image, which, although reducing the power consumption of the display, may result in poor quality of the image displayed by the display, and thus, poor user experience. For example, in the case of dim lighting conditions or low brightness settings, when an image with high average brightness is detected, the use of an auto current limit algorithm that further dims may greatly dim, making the image displayed on the display blurred.
Therefore, how to make the display device reduce power consumption and ensure the quality of the image display is a technical problem to be solved.
Disclosure of Invention
The following summary is merely exemplary and is not intended to limit the present invention in any manner. In addition to the illustrative aspects, embodiments, and features, other aspects, embodiments, and features will be apparent by reference to the drawings and the following detailed description. That is, the following summary is provided to introduce concepts, points, benefits and novel and non-obvious technical advantages described herein. Selected (but not all) embodiments will be described in further detail below. Thus, the following summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used in determining the scope of the claimed subject matter.
The present invention determines a global luminance ratio by calculating a global luminance value of an input frame image. Then, the method calculates the characteristic brightness value and the global brightness value of each pixel in the input frame image, further determines a first pixel brightness adjustment ratio and a second pixel brightness adjustment ratio according to the characteristic brightness value and the global brightness value of each pixel in the input frame image, and obtains a final pixel brightness ratio corresponding to each pixel in the input frame image according to the first pixel brightness adjustment ratio, the second pixel brightness adjustment ratio and the global brightness value; the first pixel brightness adjustment ratio can be used for keeping the image brightness, the second pixel brightness adjustment ratio can be used for keeping the image contrast, and the global brightness value is used for determining the proportion of the first pixel brightness adjustment ratio and the second pixel brightness adjustment ratio respectively when the pixel brightness ratio is calculated so as to keep the visual effect of the output frame image. Finally, the brightness of each pixel in the input frame image is adjusted according to the final pixel brightness ratio to obtain each pixel in the output frame image, so that the technical effect of reducing the overall power consumption of the output frame image and maintaining the definition of the output frame image can be achieved.
In order to enable an electronic device to reduce power consumption and maintain image display quality, the invention provides an image processing method for realizing automatic current limiting, which comprises the following steps: reducing the overall brightness of the input frame image according to the global brightness value of the input frame image; increasing the individual brightness of each pixel in the input frame image according to the absolute difference between the characteristic brightness value of each pixel and the global brightness value of the input frame image; and increasing the individual luminance of each pixel according to the characteristic luminance value of each pixel and the global luminance value of the input frame image.
The invention provides a computer storage medium comprising microcode for implementing an image processing method for automatic current limiting, wherein the image processing method comprises: reducing the overall brightness of the input frame image according to the global brightness value of the input frame image; increasing the individual brightness of each pixel in the input frame image according to the absolute difference between the characteristic brightness value of each pixel and the global brightness value of the input frame image; and increasing the individual luminance of each pixel according to the characteristic luminance value of each pixel and the global luminance value of the input frame image.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. It is to be understood that the figures are not necessarily to scale, some elements may be shown larger than actual implementation sizes in order to clearly illustrate the concepts of the present invention.
FIG. 1 is a diagram of an electronic device according to an embodiment of the invention.
Fig. 2A is a flowchart of an image processing method used in the automatic current limiter 128 of fig. 1 according to an embodiment of the present invention.
Fig. 2B is a flowchart illustrating a more detailed process of step S220 in fig. 2A according to an embodiment of the invention.
Fig. 2C is a flowchart illustrating a more detailed process of step S220 in fig. 2A according to another embodiment of the present invention.
Fig. 3 is a diagram illustrating an embodiment of obtaining a global luminance ratio corresponding to an input frame image according to a global luminance value of the input frame image and a look-up table.
Fig. 4A is a diagram illustrating an example of computing a first pixel luminance adjustment ratio corresponding to each pixel of an input frame image according to a luminance difference absolute value interpolation of a characteristic luminance value and a global luminance value of each pixel of the input frame image according to an embodiment of the invention.
Fig. 4B is a diagram illustrating a luminance adjustment ratio of a first pixel corresponding to each pixel of an input frame image according to a luminance difference absolute value interpolation of a characteristic luminance value and a global luminance value of each pixel of the input frame image according to another embodiment of the invention.
Fig. 5A and 5B are schematic diagrams illustrating an interpolation calculation of a second pixel brightness adjustment ratio corresponding to each pixel of an input frame image according to a characteristic brightness value of each pixel of the input frame image according to an embodiment of the present invention.
[ notation ] to show
100 electronic device
110 display
112I/O port
114 input structure
116 processor
118 memory
120 storage device
122 light sensor
124 networking device
126 power supply
128 automatic current limiter
200. 201, 202 method flow chart
S205, S210, S215, S220, S225
B2200, B2202, B2205, B2210, B2215 steps
C2200, C2202, C2205, C2210, C2215 steps
idx _ x [ i ], idx _ x [ i +1] luminance index values
acl _ lut, acl _ lut [ i ], aclGR, acl _ lut [ i +1] luminance ratio
Sub-pixel values of dataR, dataG, dataB pixels
First luminance value of dataY
M, N positive integer
Lavg、LMaxOriginal value of brightness value
Yavg、YMaxBrightness value
ΔLMaxOriginal value of absolute value of brightness difference
ΔYMaxAbsolute value of brightness difference
acl _ pixrthavg, acl _ pixrthavg1, acl _ pixrlowth, acl _ pixrth threshold
aclwgratioPreset value
ωcWeighted value
aclLRA and aclLRC pixel brightness adjustment ratio
aclLGR base pixel luminance ratio
Detailed Description
Aspects of the present invention will be described more fully hereinafter with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this specification. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Based on the teachings of this specification, those skilled in the art should appreciate that the scope of the present disclosure is intended to cover any embodiment disclosed in this specification, whether implemented alone or in combination with any other embodiment of the specification. For example, any number of means or performing methods set forth herein may be used to implement the method. In addition, the scope of the present invention is intended to cover apparatuses or methods implemented using other structures, functions, or structures and functions in addition to the embodiments disclosed herein. It is to be understood that any embodiment disclosed herein may be embodied by one or more elements of a claim.
The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment of the present disclosure or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments of the present disclosure or design.
Although specific embodiments have been described herein, many variations and permutations of these embodiments fall within the scope of the invention. Although some benefits and advantages of the preferred embodiments are mentioned, the scope of the invention is not intended to be limited to a particular benefit, use or objective. Rather, the invention is intended to be broadly applicable to different technologies, system configurations, networks and protocols, some of which are illustrated by way of example in the accompanying drawings and in the following description of the preferred embodiments. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.
The invention relates to an image processing method and device for realizing automatic current limiting. Organic Light Emitting Diode (OLED) displays can display images on the entire display using an OLED array; each OLED subpixel emits light of a particular color and brightness based on the drive current it receives. In an embodiment, red, green, and blue emitters may be used to display various colors. In another embodiment, a white emitter may be used and a color filter or fluorescent material is used to convert the white color to the respective color. The emitted light may be red, green and blue, but also another white sub-pixel may be used. In another embodiment, red, green, and blue emitters may be used to emit various colors, and these colors may be further refined by passing through a set of color filters such that each emitted color matches a color filter of a particular color.
Various electronic devices may incorporate OLED displays with Automatic Current Limiting (ACL). Examples of suitable electronic devices may include various internal and/or external components that facilitate the function of the device. FIG. 1 is a diagram of an electronic device 100 according to an embodiment of the invention. Those skilled in the art will appreciate that the various functional modules illustrated in fig. 1 may include hardware elements (including circuitry), software elements (including computer program code stored on a computer-readable medium) or a combination of both hardware and software elements. It should also be noted that fig. 1 is merely an example of a particular implementation and is intended to illustrate only the types of elements that may be present in electronic device 100. For example, in the presently illustrated embodiment, electronic device 100 may include a display 110, an I/O port 112, an input structure 114, one or more processors 116, a memory 118, a storage device 120, one or more light sensors 122, a networking device 124, a power supply 126, and an Automatic Current Limiter (ACL) 128.
For each of these elements, the display 110 may be used to display various images generated by the electronic device 100. In one embodiment, the display 110 may be an Organic Light Emitting Diode (OLED) display. An OLED display may include a plurality of pixels or picture elements that may be used to show an image on the display 110. In an OLED display, each pixel may be composed of three pixel components (also referred to as sub-pixels), red, green, and blue, respectively; alternatively, four pixel components, namely red, green, blue and white, may be employed. Each sub-pixel may display a corresponding color using an electroluminescent layer (i.e., an organic compound film) that emits light in response to current. The color of the light observed may be the light emitted directly by the sub-pixels or the color changed by passage through a color filter comprising an absorbing material or a fluorescent material. Thus, the display 110 may use a relatively high power level when a bright image is presented on the display 110.
The I/O ports 112 may include ports configured to connect to a variety of external devices, such as a power supply, a headset or sound box, or other electronic devices (such as handheld devices and/or computers, printers, projectors, external displays, modems, expansion slots, etc.). The input structures 114 may include various devices, circuits, and paths for providing user input or feedback to the processor 116. Input structures 114 may be configured to control functions of electronic device 100, applications running on electronic device 100, and/or any interface or device connected to electronic device 100 or used by electronic device 100.
The one or more processors 116 may provide processing capabilities to execute the operating system, programs, user and application interfaces, and any other functions of the electronic device 100. Instructions or data processed by the one or more processors 116 may be stored in a computer-readable medium, such as memory 118. The Memory 118 may be volatile Memory, such as Random Access Memory (RAM), and/or non-volatile Memory, such as Read-only Memory (ROM). Electronic device 100 may further include other forms of computer-readable media, such as storage device 120, where storage device 120 may be a non-volatile storage device for persistently storing data and/or instructions. Storage 120 may also include flash memory, a hard drive, or other optical, magnetic, and/or firmware storage media for storing firmware, data files, software, wireless connection information, and any other suitable data.
The electronic device 100 shown in fig. 1 may also include one or more light sensors 122. The light sensor 122 may include a sensor such as a photodetector, photodiode, photo resistors (photo resistors), photo cells (photo cells), or any other sensor capable of detecting ambient light. In various embodiments, the light sensor 122 may be disposed on the substrate such that it receives light from the substrate direction, the direction opposite the substrate, or both. In some embodiments, a camera may be mounted in the electronic device 100 and act as a light sensor.
The electronic device 100 shown in fig. 1 further includes a Network connection device 124, such as a Network controller or a Network Interface Card (NIC). The network device 124 may be a Wi-Fi device, a radio frequency device, a Bluetooth device,
Figure BDA0001841234050000061
Devices, cellular communication devices, and the like. Network device 124 may allow electronic device 100 to communicate over a Network, such as a Local Area Network (LAN), Wide Area Network (WAN), or the Internet (Internet). Additionally, the electronic device 100 may also include a power source 126, such as a battery or an alternating current power source.
To prevent the display 110 from consuming power excessively, the electronic device 100 may also include an automatic current limiter 128. The automatic current limiter 128 may monitor the overall power or current used by the display 110 and reduce the overall power consumption in the display 110 by controlling the current provided to the display 110. In one embodiment, the automatic current limiter 128 may estimate the power consumption expected for an image frame to be displayed on the display 110 and may be capable of automatically adjusting the brightness of the output frame image based on the content of the input frame image to reduce the power consumption of the display 110 and maintain the visual effect of the output frame image.
Fig. 2 is a flow chart 200 of an image processing method used in the automatic current limiter 128 of fig. 1. The process flow shown in the method flow chart 200 can be implemented in two embodiments, the first embodiment can be described with reference to fig. 2B, 3, 4A, 5A, and 5B, and the second embodiment can be described with reference to fig. 2C, 3, 4B, 5A, and 5B. A first embodiment of the method flowchart 200 is described below with reference to fig. 2B, 3, 4A, 5A, and 5B.
In step S205, the auto current limiter 128 receives an input frame image. In step S210, the auto-limiter 128 calculates a global luminance value of the input frame image. In more detail, the auto-limiter 128 calculates a luminance value (also referred to as a first luminance value) of each pixel in the input frame image, accumulates the luminance values of each pixel, and averages the accumulated luminance values to obtain a global luminance value of the input frame image. The luminance value of each pixel can be calculated from the sub-pixel values of the red channel, the green channel and the blue channel of each pixel according to a conversion formula, wherein the conversion formula is expressed as follows:
dataY＝ω1×dataR+ω2×dataG+ω3×dataB
where dataY is the first luminance value, dataR, dataG, and dataB are the sub-pixel values of the red, green, and blue channels, ω, respectively, of a pixel in the input frame image1、ω2And omega3Each weight value is between 0 and 1. In one embodiment, ω is1、ω2And omega3The sum of (a) and (b) is 1. in another embodiment, the above conversion formula may further include a constant term. Therefore, the global luminance value original value L of the input frame imageavgCan be expressed as follows:
Figure BDA0001841234050000071
wherein, dataYijA first luminance value corresponding to the jth column of row i (or jth column jth row) pixels in the input frame image, Μ, Ν are positive integers, and Μ × Ν is the total number of pixels in the input frame image.
At another placeIn one embodiment, the original value L of the global luminance valueavgA first luminance value dataY corresponding to the brightest pixel or the darkest pixel in the input frame image. The present invention is not limited thereto, and any value that can represent the global feature of the input frame image can be used as the global luminance value original value Lavg。
Global luminance value YavgFor global luminance value original value L of input frame imageavgNormalized value, global luminance value YavgThe maximum value is 1 and the minimum value is 0.
In step S215, the automatic current limiter 128 calculates a characteristic luminance value of each pixel of the input frame image. In more detail, the original value L of the characteristic luminance value of each pixel of the input frame imageMaxIs represented as follows:
LMax＝MAX(dataR，dataG，dataB)
where MAX (dataR, dataG, dataB) is the maximum value among the subpixel values dataR, dataG, and dataB corresponding to the three channels of red, green, and blue in each pixel. In another embodiment, the original value L of the characteristic brightness value of each pixelMaxIs the first luminance value dataY of the corresponding pixel. In other embodiments, the original value L of the characteristic brightness value of each pixelMaxMay take the value of the sub-pixel value dataR or dataG or dataB of the corresponding pixel.
Characteristic brightness value YMaxFor a characteristic luminance value original value L of each pixel of an input frame imageMaxNormalized value, characteristic brightness value YMaxThe maximum value is 1 and the minimum value is 0.
In step S220, the auto-limiter 128 determines a characteristic luminance value Y of each pixel in the input frame imageMaxAnd global luminance value Y of input frame imageavgCalculating the final pixel brightness ratio aclLR of each pixel; fig. 2B is a flowchart 201 illustrating a more detailed process of step S220 in fig. 2A according to an embodiment of the present invention, and the flowchart 201 will be described in more detail with reference to fig. 3, fig. 4A, fig. 5A, and fig. 5B.
In step B2200, the auto current limiter 128 computes each of the input frame imagesCharacteristic luminance value Y of a pixelMaxAnd global luminance value Y of input frame imageavgAbsolute value of luminance difference Δ Y ofMax(ii) a Original value of brightness difference value DeltaLMaxIs represented as follows:
ΔLMax＝|Lavg-LMax| (1)
in another embodiment, the original value of the absolute value of the brightness difference Δ LMaxCan be substituted by another formula (2), which is expressed as follows:
ΔLMax＝MAX(|Lavg-dataR|，|Lavg-dataG|，|Lavg-dataB|) (2)
wherein L isavgFor the global luminance value original value, dataR, dataG, data beta are the sub-pixel values of the red, green and blue channels in each pixel in the input frame image; MAX (| L)avg-dataR|，|Lavg-dataG|，|Lavg-dataB |) represents taking | Lavg-dataR|、|Lavg-dataG|、|Lavg-maximum among dataB |.
Absolute value of brightness difference DeltaYMaxIs the original value of the absolute value of the brightness difference Δ LMaxNormalized value, absolute value of brightness difference DeltaYMaxThe maximum value is 1 and the minimum value is 0.
In step B2202, the auto-limiter 128 operates on the global luminance value Y of the input frame imageavgA global luminance ratio aclGR is determined and then a base pixel luminance ratio aclLGR for each pixel in the input frame image is calculated based on the global luminance ratio aclGR. In particular, the auto-limiter 128 may be based on a look-up table and the global luminance value Y of the input frame imageavgA global luminance ratio aclGR is determined and then a base pixel luminance ratio aclLGR for each pixel in the input frame image is calculated based on the global luminance ratio aclGR. In other words, the global luminance value Y of the input frame image is found in the look-up tableavgThe corresponding luminance ratio is used as the global luminance ratio aclGR of the input frame image, and the luminance of each pixel in the input frame image is reduced by using the global luminance ratio aclGR, that is, the luminance of each pixel in the input frame image is calculated according to the global luminance ratio aclGRThe basic pixel luminance ratio aclLGR of the pixel is used to reduce the overall luminance of the input frame image so as to achieve the purpose of power saving without affecting the visual effect. For example, in FIG. 3, assume that the lookup table includes a luminance index value idx _ x [ i [ ]]、idx_x[i+1]And respectively correspond to luminance index values idx _ x [ i]、idx_x[i+1]Luminance ratio acl _ lut [ i ]]、acl_lut[i+1](ii) a As shown in fig. 3, the horizontal axis may represent the luminance index value, the vertical axis may represent the luminance ratio, and the luminance ratio corresponding to the luminance index value may be obtained by the lookup table. It should be noted that, as shown in FIG. 3, the luminance index value idx _ x [ i ]]Less than the luminance index value idx _ x [ i +1 [)]Luminance ratio acl _ lut [ i ]]Greater than the luminance ratio acl _ lut [ i +1]](ii) a When the global brightness value Y of the input frame imageavgWhen the brightness of the whole domain of the input frame image is smaller, the global brightness ratio aclGR of the input frame image is set to be a larger value, so that the smaller brightness of the darker input frame image is reduced to avoid the displayed image from being too dark, and the whole brightness and the visual effect of the input frame image are further ensured; when the global brightness value Y of the input frame imageavgWhen larger, the global luminance ratio aclGR of the input frame image is set to a smaller value, which will give a brighter input frame image a larger luminance reduction to avoid the displayed image being too bright. Therefore, after the adjustment of the global luminance ratio aclGR, the visual effect can be maintained even when the overall luminance of the input frame image is reduced. In other words, if the global luminance value Y of an input frame imageavgIs larger than the global brightness value Y of another input frame imageavgThe global luminance ratio aclGR of the input frame image is smaller than the global luminance ratio aclGR of another input frame image; if the global brightness value Y of an input frame imageavgGlobal luminance value Y smaller than another input frame imageavgThe global luminance ratio aclGR of the input frame image is greater than that of another input frame image. In one embodiment, a slope value of the luminance index and the luminance ratio can be obtained through a lookup table, and then the corresponding global luminance value Y can be calculated according to the slope valueavgThe global luminance ratio aclGR. For example, the global luminance ratio aclGR may be calculated by the following equation (3):
Figure BDA0001841234050000091
it should be noted that in the present embodiment, the lookup table only includes two sets of luminance index values idx _ x [ i]、idx_x[i+1]And its corresponding luminance ratio acl _ lut [ i ]]、acl_lut[i+1](since can pass (idx _ x [ i ]]，acl_lut[i]) And (idx _ x [ i +1]]acl_lut[i+1]) The line defined by the two points calculates the global luminance ratio aclGR), but the present invention is not limited thereto. For example, in one embodiment, the lookup table may include eight sets of luminance index values and corresponding luminance ratios, such that the global luminance value YavgPossibly in seven intervals of luminance index values. In one embodiment, the lookup table is built by the processor 116 after the automatic current limiter 128 is accessed, but the invention is not so limited.
As previously described, the global luminance ratio aclGR may be used to reduce the overall luminance of the input frame image to obtain a base pixel luminance ratio aclLGR for each pixel of the input frame image. In one embodiment, the automatic current limiter 128 uses the global luminance ratio aclGR of the input frame image as the base pixel luminance ratio aclLGR for each pixel to reduce the overall luminance of the input frame image. In another embodiment, a region is drawn with the center point of the input frame image as the center for the human eye to watch the image, wherein the drawn region may be a circle with the center point of the image as the center point, or a square or rectangle with the center point of the image as the center point, but the invention is not limited thereto, and the drawn region may be in any shape; the auto current limiter 128 uses the global luminance ratio aclGR of the input frame image as the base pixel luminance ratio aclLGR of each pixel within the drawn area, and uses a value smaller than the global luminance ratio aclGR of the input frame image as the base pixel luminance ratio aclLGR of each pixel outside the drawn area, to reduce the overall luminance of the input frame image. In another embodiment, the input frame image may be divided into a plurality of regions, each region using a value related to the global luminance ratio aclGR of the input frame image as the base pixel luminance ratio aclLGR of each pixel to reduce the overall luminance of the input frame image. The present invention is not limited thereto and any method of dividing the input frame image may be used to calculate a base pixel luminance ratio aclLGR of each pixel for reducing the overall luminance of the input frame image.
Next, in order to reduce the overall brightness of the input frame image while maintaining the visual effect of the output frame image, the auto current limiter 128 calculates a first pixel brightness adjustment ratio aclLRA and a second pixel brightness adjustment ratio aclLRC for each pixel of the input frame image, and then calculates a final pixel brightness ratio aclLR for each pixel from the base pixel brightness ratio aclLGR, the first pixel brightness adjustment ratio aclLRA, and the second pixel brightness adjustment ratio aclLRC for each pixel of the input frame image, as follows.
In step B2205, the automatic current limiter 128 determines the absolute value of the brightness difference Δ YMaxA corresponding first pixel luminance adjustment ratio aclLRA is generated for increasing the individual luminance of each pixel in the input frame image. Specifically, as shown in fig. 4A, the automatic current limiter 128 calculates the absolute value of the brightness difference Δ Y according to the formula (1) or (2)MaxTo calculate the first pixel brightness adjustment ratio aclLRA of each pixel, so as to make the absolute value of the brightness difference Δ Y of the pixelMaxThe smaller one (i.e. the characteristic luminance value Y of the pixel)MaxGlobal luminance value Y closer to input frame imageavg) Has larger brightness amplification and absolute value of brightness difference value delta YMaxThe larger one (i.e. the characteristic luminance value Y of the pixel)MaxGlobal luminance value Y of the farther away from the input frame imageavg) With less brightness increase. This makes it possible to make the absolute value of the luminance difference Δ YMaxLarger absolute value of pixel ratio brightness difference DeltaYMaxSmaller pixels have less brightness increase to achieve the goal of maintaining the brightness of the input frame image. In detail, the auto-limiter 128 will limit the absolute value of all brightness differences Δ YMaxThe corresponding first pixel luminance adjustment ratio aclLRA is set as the first threshold acl _ pixrthavg, and all the luminance difference absolute values Δ Y are set as the lowest luminance difference absolute valuesMaxIs defined as the absolute value of the highest luminance difference value, and the corresponding first pixel luminance adjustment ratio aclLRA is set to 0. Therefore, the first pixel luminance adjustment ratio aclLRA corresponding to each pixel in the input frame image can be calculated by interpolation calculation. It should be noted thatThat is, the lowest luminance difference value in fig. 4A may be recorded as 0, and the highest luminance difference value may be recorded as 1. The horizontal axis in fig. 4A represents the absolute value of the luminance difference value for each pixel, and the vertical axis represents the first pixel luminance adjustment ratio. In one embodiment, the first threshold acl _ pixrthavg can be a predetermined value, and the first threshold acl _ pixrthavg is greater than 0. The operation of the first pixel luminance adjustment ratio aclLRA corresponding to each pixel of the input frame image will be further described with reference to the second pixel luminance adjustment ratio aclLRC. As shown in fig. 4A, the first pixel luminance adjustment ratio aclLRA corresponding to the input frame pixel having a luminance difference absolute value between 0 and 1 can be interpolated by the following formula (4):
aclLRA＝acl_pixrthavg X(1-ΔYMax) (4)
therefore, the absolute value of the luminance difference Δ Y of each pixel in the input frame image can be calculated using the above formulaMaxThe corresponding first pixel brightness adjustment ratio aclLRA.
In step B2210, the auto-limiter 128 calculates a characteristic luminance value Y for each pixel in the input frame image based on the luminance valuesMaxAnd global luminance value Y of input frame imageavgA corresponding second pixel luminance adjustment ratio aclLRC is generated for increasing the individual luminance of each pixel in the input frame image. In detail, the auto-limiter 128 is based on the characteristic luminance value Y of each pixel in the input frame imageMaxAnd global luminance value Y of input frame imageavgThe second pixel luminance adjustment ratio aclLRC corresponding to each pixel in the input frame image is determined, wherein the second pixel luminance adjustment ratio aclLRC can maintain the contrast of the output frame image, which will be described in detail below with reference to fig. 5A and 5B.
In detail, when the characteristic brightness value Y of each pixel in the input frame imageMaxGlobal luminance value Y smaller than input frame imageavgThen, the characteristic brightness value Y of these input frame pixels is calculatedMaxThe second pixel luminance adjustment ratio aclLRC corresponding to the minimum value in (b) is set to the second threshold value acl _ pixrlowth (as shown in fig. 5A); when the characteristic brightness value Y of the input frame pixel in the input frame imageMaxGlobal luminance greater than input frame imageValue YavgThen, the characteristic brightness value Y of these pixels is calculatedMaxThe second pixel luminance adjustment ratio aclLRC corresponding to the maximum value in (B) is set to the third threshold acl _ pixrth (as shown in fig. 5B); when the characteristic brightness value Y of the input frame pixel in the input frame imageMaxEqual to the global luminance value Y of the input frame imageavgThen, the second pixel luminance adjustment ratio aclLRC corresponding to the input frame pixel is set to 0. Therefore, the characteristic luminance value Y of each pixel in the input frame image can be determinedMaxThe second pixel luminance adjustment ratio aclLRC corresponding to each pixel is calculated by interpolation. Thus, by determining the second pixel luminance adjustment ratio aclLRC of the pixels in the input frame image according to fig. 5A and 5B, (1) the characteristic luminance value Y can be setMaxIn the global brightness value YavgThe brightness of the nearby pixels is adjusted slightly; (2) characteristic brightness value YMaxDistance global luminance value YavgThe brightness of the farther pixels is adjusted more. Then, after such processing, the characteristic luminance value YMaxMinimum pixel and characteristic luminance value YMaxThe maximum pixel brightness increase is large and thus the contrast of the input frame image display is maintained.
FIG. 5A shows the characteristic luminance value Y of a pixel of an input frameMaxGlobal luminance value Y smaller than input frame imageavgAn embodiment of determining a second pixel brightness adjustment ratio aclLRC corresponding to an input frame pixel, wherein the horizontal axis represents a characteristic brightness value of the input frame pixel and the vertical axis represents the second pixel brightness adjustment ratio, and the characteristic brightness value Y is obtained by dividing the characteristic brightness value by the average brightness valueMaxIs 0 (i.e., the original value L of the characteristic luminance value in the input frame pixel)MaxSmallest) of the input frame pixels is set to a second threshold value acl _ pixrlowth, setting the characteristic luminance value Y to a second pixel luminance adjustment ratio aclLRC of the input frame pixelsMaxEqual to the global luminance value YavgThe second pixel luminance adjustment ratio aclLRC of the input frame pixel is set to 0, and the characteristic luminance value Y is set toMaxGlobal luminance value Y from 0 to input frame imageavgThe second pixel luminance adjustment ratio aclLRC corresponding to the input frame pixel in between can be interpolated by the following equation (5):
aclLRC＝acl_pixrlowth×(Yavg-YMax)/Yavg(5)
FIG. 5B shows the characteristic luminance value Y of a pixel when an input frame is inputtedMaxGlobal luminance value Y greater than input frame imageavgOne embodiment of determining the second pixel brightness adjustment ratio aclLRC for the input frame pixel, wherein the horizontal axis represents the characteristic brightness value of the input frame pixel, the vertical axis represents the second pixel brightness adjustment ratio, and the characteristic brightness value is set to 1 (i.e., the original value L of the characteristic brightness value in the input frame pixel)MaxMaximum) is set to the third threshold value acl _ pixrth, the characteristic luminance value is equal to the global luminance value YavgThe second pixel luminance adjustment ratio aclLRC of the input frame pixel is set to 0, and the characteristic luminance value Y is set toMaxGlobal luminance value Y from 1 to the input frame imageavgThe second pixel luminance adjustment ratio aclLRC corresponding to the input frame pixel in between can be interpolated by the following equation (6):
aclLRC＝acl_pixrth×(YMax-Yavg)/(1-Yavg) (6)
in one embodiment, the second threshold acl _ pixrlowth and the third threshold acl _ pixrth may be preset values, and the third threshold acl _ pixrth and the second threshold acl _ pixrlowth are both greater than 0, so that each pixel in the input frame image is again adjusted to be high-luminance after the input frame pixel is processed as shown in fig. 3. And the characteristic brightness value YMaxAnd global luminance value YavgThe pixels having larger differences (for example, the pixels having the characteristic luminance values closer to 1 in fig. 5B or the pixels having the characteristic luminance values closer to 0 in fig. 5A) are adjusted higher again in luminance by a larger magnitude, so that the contrast of the output frame image can be maintained. Further, the present invention is not limited to the characteristic luminance value Y according to each pixel in the input frame imageMaxAnd global luminance value Y of input frame imageavgThe second pixel luminance adjustment ratio aclLRC corresponding to each pixel in the input frame image is determined. For example, in one embodiment, the auto current limiter 128 may also be based on the absolute value of the luminance difference Δ Y for each pixel in the input frame imageMaxAnd global luminance value Y of input frame imageavgTo determine each of the input frame imagesA second pixel luminance adjustment ratio aclLRC corresponding to a pixel. Accordingly, equation (5) may be replaced by equation (7), and equation (6) may be replaced by equation (8), where equations (7) and (8) may be expressed as:
aclLRC＝acl_pixrlowth×ΔYMax/Yavg(7)
aclLRC＝acl_pixrth×ΔYMax/(1-Yavg) (8)
in other words, the present invention depends on the characteristic luminance value Y of each pixel in the input frame imageMaxAnd global luminance value Y of input frame imageavgThe second pixel luminance adjustment ratio aclLRC corresponding to each pixel in the input frame image can be determined.
In the above embodiment, the basic pixel luminance ratio aclLGR is calculated first, the first pixel luminance adjustment ratio aclLRA is calculated, and the second pixel luminance adjustment ratio aclLRC is calculated only finally. However, the present invention is not limited thereto, and in another embodiment, the first pixel luminance adjustment ratio aclLRA may be calculated first, then the second pixel luminance adjustment ratio aclLRC may be calculated, and finally the basic pixel luminance ratio aclLGR may be calculated; that is, in the present invention, the calculation of the base pixel luminance ratio aclLGR, the first pixel luminance adjustment ratio aclLRA, and the second pixel luminance adjustment ratio aclLRC may be performed in an arbitrary order.
In step B2215, the auto-limiter 128 adjusts the luminance of each pixel in the input frame image according to the corresponding basic pixel luminance ratio aclLGR, the first pixel luminance adjustment ratio aclLRA, the second pixel luminance adjustment ratio aclLRC and the global luminance value Y of the input frame imageavgCalculating a final pixel luminance ratio aclLR for each pixel, wherein the final pixel luminance ratio aclLR for each pixel in the input frame image can be calculated by equation (9):
aclLR＝aclLGR+ωc×aclLRC+(1-ωc)×aclLRA (9)
wherein ω iscIs a weight value between 0 and 1, and the weight value omegacCan be calculated according to the following equation (10):
ωc＝aclwgratio×(1-Yavg) (10)
acl thereinwgratioThe preset value can be adjusted by a display operator or a consumer to determine the brightness and/or contrast of the output frame image. For example, before the display leaves the factory, the manufacturer adjusts acl according to the condition of the individual panelwgratioAnd after the value is adjusted to the most appropriate value, the value is written into a ROM or a Flash of a display for storage, and the value is used for adjusting the display of the input frame image on a panel. As can be seen from the equation (10), the global luminance value Y of the input frame image can be usedavgCalculating a weight value omegacIf the global luminance value Y of the input frame imageavgThe larger the weight value omegacThe smaller, the larger the weight occupied by the first pixel luminance adjustment ratio aclLRA and the smaller the weight occupied by the second pixel luminance adjustment ratio aclLRC when calculating the final pixel luminance ratio aclLR of the input frame pixel according to equation (9); on the contrary, if the global luminance value Y of the input frame imageavgThe smaller the weight value omegacThe larger the ratio, the smaller the proportion of the first pixel luminance adjustment ratio aclLRA and the larger the proportion of the second pixel luminance adjustment ratio aclLRC when calculating the final pixel luminance ratio aclLR of the input frame pixels according to equation (9). By such processing, the luminance value Y having a small global area is obtainedavgThe output frame image corresponding to the input frame image can maintain more contrast and has larger global brightness value YavgThe output frame image corresponding to the input frame image can keep less contrast, thereby avoiding the expansion of noise, and realizing the purpose of keeping the display visual effect while reducing the overall brightness of the output frame image.
In step S225, the automatic current limiter 128 adjusts the luminance of each pixel of the input frame image according to the final pixel luminance ratio aclLR corresponding to each pixel. In more detail, the auto current limiter 128 multiplies the red, green and blue channel values of each pixel in the input frame image by the final pixel luminance ratio aclLR corresponding to each pixel to obtain an adjustment value of each pixel of the input frame image, and transmits the adjustment value of each pixel to the display to display the output frame image.
A second embodiment of the method flowchart 200 is described below in conjunction with fig. 2C, 3, 4B, 5A, and 5B; the second embodiment of the method flowchart 200 differs from the first embodiment thereof mainly in that in step S220, a first pixel luminance adjustment ratio aclLRA is calculated by reducing the luminance of each pixel of the input frame image. Fig. 2C is a flowchart 202 illustrating a more detailed process of step S220 in fig. 2A according to an embodiment of the invention, and the flowchart 202 will be described in more detail with reference to fig. 3, fig. 4B, fig. 5A and fig. 5B.
The specific operations of steps C2200, C2202, C2210 and C2215 in the process flow 202 in fig. 2C are the same as the corresponding steps B2200, B2202, B2210 and B2215 in the process flow 201 in fig. 2B; only the specific operation of step C2205 in the process flow 202 in fig. 2C differs from the corresponding specific operation of step B2205 in the process flow 201 in fig. 2B, and only the specific operation flow of step C2205 in the process flow 202 in fig. 2C will be described below.
In step C2205, the automatic current limiter 128 determines the absolute value of the brightness difference Δ YMaxA corresponding first pixel brightness adjustment ratio aclLRA is generated for reducing the individual brightness of each pixel in the input frame image. Specifically, as shown in fig. 4B, the automatic current limiter 128 calculates the absolute value of the brightness difference Δ Y according to the formula (1) or (2)MaxCalculating a first pixel luminance adjustment ratio aclLRA by reducing the luminance of each pixel of the input frame image to make the absolute value of the luminance difference Δ Y of the pixelMaxThe smaller one (i.e. the characteristic luminance value Y of the pixel)MaxGlobal luminance value Y closer to input frame imageavg) Has smaller brightness reduction amplitude, and the absolute value of the brightness difference value delta YMaxThe larger one (i.e. the characteristic luminance value Y of the pixel)MaxGlobal luminance value Y of the farther away from the input frame imageavg) Has larger brightness reduction amplitude. This makes it possible to make the absolute value of the luminance difference Δ YMaxLarger absolute value of pixel ratio brightness difference DeltaYMaxThe smaller pixels have larger brightness reduction to achieve the purpose of keeping the brightness of the input frame image. In detail, the auto-limiter 128 will limit the absolute value of all brightness differences Δ YMaxThe minimum value of the first and second pixel brightness adjustment ratios is defined as the absolute value of the lowest brightness difference, and the corresponding first pixel brightness adjustment ratio aclLRA is set toSet to 0, all luminance difference absolute values DeltaYMaxIs defined as the highest luminance difference absolute value, and the corresponding first pixel luminance adjustment ratio aclLRA is set to the fourth threshold acl _ pixrthavg 1. Therefore, the first pixel luminance adjustment ratio aclLRA corresponding to each pixel in the input frame image can be calculated by interpolation calculation. Note that the lowest luminance difference absolute value in fig. 4B may be written as 0, and the highest luminance difference absolute value may be written as 1. The horizontal axis in fig. 4B represents the absolute value of the luminance difference value for each pixel, and the vertical axis represents the first pixel luminance adjustment ratio. In one embodiment, the fourth threshold acl _ pixrthavg1 may be a predetermined value, and the fourth threshold acl _ pixrthavg1 is less than 0. In this way, the individual brightness of each pixel in the input frame image can be reduced. As shown in fig. 4B, the first pixel luminance adjustment ratio aclLRA corresponding to each pixel of the input frame image having a luminance difference absolute value between 0 and 1 can be interpolated by the following formula (4'):
aclLRA＝acl_pixrthavg1XΔYMax(4’)
in the present embodiment, since the brightness of the individual pixels is reduced again after the overall brightness of the input frame image is reduced, the second threshold acl _ pixrlowth and the third threshold acl _ pixrth in fig. 5A and 5B may be set higher than the second threshold acl _ pixrlowth and the third threshold acl _ pixrth set in the first embodiment using the method flowchart 200 of fig. 4A, so that the brightness of the individual pixels can be greatly increased to achieve better display effect.
In another embodiment, the third threshold acl _ pixrth may be set higher than the second threshold acl _ pixrlowth, so that the brightness value of the brighter pixel is increased by a larger magnitude than the brightness value of the dark pixel, so as to further increase the brightness value of the brighter pixel and further increase the contrast of the image.
In summary, the display brightness of each pixel in the input frame image is automatically adjusted according to the final pixel brightness ratio aclLR corresponding to each pixel in the input frame image, so that the overall power consumption of the display is reduced; moreover, the automatic current limiting adjusting mode adopted by the invention is simple, and the display quality of the output frame image can be ensured, such as the definition and/or the contrast of the output frame image are better.
In addition, in one embodiment, the processor 116 in the electronic device 100 can also execute the programs and instructions in the memory 118 to perform the actions and steps described in the above embodiments.
Any particular order of the processes disclosed herein is merely an example. Based upon design preferences, it should be understood that any specific order in a process may be rearranged within the scope of the present disclosure. The corresponding method claims present an order of the steps in an example sequence, and therefore should not be limited to the specific order presented.
The use of the ordinal terms "first," "second," "third," etc., in the claims to modify an element does not by itself connote any priority, precedence, order of various elements, or order of steps performed by the method, but are used merely to distinguish one element from another element having a same name (but for use of a different ordinal term).
Although the present disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present disclosure, and therefore, the scope of the present disclosure is to be determined by the terms of the appended claims.

Claims (17)

1. An image processing method for implementing automatic current limiting, comprising:
reducing the overall brightness of the input frame image according to the global brightness value of the input frame image;
increasing the individual brightness of each pixel in the input frame image according to the absolute value of the difference between the characteristic brightness value of each pixel and the global brightness value of the input frame image; and
increasing the individual luminance of each pixel according to the characteristic luminance value of each pixel and the global luminance value of the input frame image; wherein the method further comprises:
determining a first pixel brightness adjustment ratio and a second pixel brightness adjustment ratio according to a characteristic brightness value of each pixel in the input frame image and the global brightness value of the input frame image;
obtaining a final pixel brightness ratio corresponding to each pixel in the input frame image according to the first pixel brightness adjustment ratio, the second pixel brightness adjustment ratio, and the global brightness value of the input frame image; wherein,
the global brightness value is used to determine a ratio of the first pixel brightness adjustment ratio and the second pixel brightness adjustment ratio in calculating the final pixel brightness ratio,
the larger the global brightness value is, the larger the proportion of the first pixel brightness adjustment ratio is, and the smaller the proportion of the second pixel brightness adjustment ratio is; and
when the global brightness value is smaller, the proportion of the first pixel brightness adjustment ratio is smaller, and the proportion of the second pixel brightness adjustment ratio is larger.
2. The image processing method of claim 1, further comprising:
determining a global luminance ratio corresponding to the input frame image according to the global luminance value; and
and reducing the overall brightness of the input frame image according to the global brightness ratio of the input frame image.
3. The image processing method according to claim 2, wherein the larger the global luminance value of the input frame image, the lower the global luminance ratio corresponding to the input frame image.
4. The image processing method according to claim 3, wherein the calculation formula of the global luminance ratio corresponding to the input frame image is:
Figure FDA0002487825950000011
wherein aclGR is the global luminance ratio, Y, corresponding to the input frame imageavgThe global luminance value of the input frame image, idx _ x [ i ]]And idx _ x [ i +1]]Is a luminance index value, acl _ lut [ i ]]And acl _ lut [ i +1]]Is indexed by the luminance index value idx _ x [ i]And idx _ x [ i +1]]Corresponding luminance ratio, wherein the luminance index value idx _ x [ i ]]Less than the luminance index value idx _ x [ i +1 [)]Luminance ratio acl _ lut [ i ]]Greater than the luminance ratio acl _ lut [ i +1]]。
5. The image processing method according to claim 1,
the larger the absolute value of the difference between the characteristic luminance value of each pixel and the global luminance value of the input frame image is, the smaller the magnitude by which the individual luminance of each pixel is increased.
6. The image processing method according to claim 5, wherein the first pixel luminance adjustment ratio corresponding to each pixel is generated based on an absolute difference value between the characteristic luminance value of each pixel in the input frame image and the global luminance value of the input frame image, and the individual luminance of each pixel is increased using the first pixel luminance adjustment ratio, wherein the first pixel luminance adjustment ratio is calculated using the following formula:
aclLRA＝acl_pixrthavg×(1-ΔYMax)
wherein aclLRA is the first pixel brightness adjustment ratio, acl _ pixrthavg is the first threshold, Δ YMaxWherein acl _ pixrthavg is greater than 0, and is an absolute value of a difference between the characteristic luminance value of each pixel in the input frame image and the global luminance value of the input frame image.
7. The image processing method according to claim 1,
a characteristic luminance value of a brightest pixel among the pixels is larger than the global luminance value of the input frame image, and an absolute value of a difference between the characteristic luminance value of the brightest pixel and the global luminance value of the input frame image is a maximum value; and
a characteristic luminance value of a darkest pixel among the pixels is smaller than the global luminance value of the input frame image, and an absolute value of a difference between the characteristic luminance value of the darkest pixel and the global luminance value of the input frame image is a maximum value.
8. The image processing method according to claim 7,
a characteristic luminance value of a brighter pixel of the pixels is greater than the global luminance value of the input frame image and a characteristic luminance value of the brighter pixel is less than a characteristic luminance value of a brightest pixel of the pixels; and
a characteristic luminance value of a darker pixel of the pixels is smaller than the global luminance value of the input frame image and a characteristic luminance value of the darker pixel is larger than a characteristic luminance value of a darkest pixel of the pixels.
9. The image processing method according to claim 7, wherein the second pixel luminance adjustment ratio for each pixel is generated based on the characteristic luminance value of each pixel and the global luminance value of the input frame image, and the individual luminance of each pixel is increased using the second pixel luminance adjustment ratio, wherein when the characteristic luminance value of each pixel is smaller than the global luminance value of the input frame image, the second pixel luminance adjustment ratio is calculated using the following formula:
aclLRC＝acl_pixrlowth×(Yavg-YMax)/Yavg
when the characteristic luminance value of the pixel is greater than the global luminance value of the input frame image, a formula for calculating the second pixel luminance adjustment ratio is as follows:
aclLRC＝acl_pixrth×(YMax-Yavg)/(1-Yavg)
when the characteristic luminance value of the pixel is equal to the global luminance value of the input frame image, the second pixel luminance adjustment ratio is 0;
wherein aclLRC isThe second pixel brightness adjustment ratio is acl _ pixrlowth as the second threshold, acl _ pixrth as the third threshold, YavgIs the global luminance value, Y, of the input frame imageMaxThe characteristic luminance value of the pixel.
10. The image processing method of claim 1, further comprising:
generating a base pixel luminance ratio for each pixel of the input frame image based on the global luminance value;
generating the first pixel luminance adjustment ratio of the input frame image according to an absolute difference value between the feature luminance value of each pixel in the input frame image and the global luminance value of the input frame image; and
and generating the second pixel luminance adjustment ratio of the input frame image based on the characteristic luminance value of each pixel and the global luminance value of the input frame image.
11. The image processing method of claim 10, further comprising:
and reducing the luminance of each pixel in the input frame image based on the base pixel luminance ratio, the first pixel luminance adjustment ratio, the second pixel luminance adjustment ratio, and the global luminance value of each pixel in the input frame image.
12. The image processing method of claim 11, further comprising:
the final pixel luminance ratio for each pixel of the input frame image is generated based on the base pixel luminance ratio, the first pixel luminance adjustment ratio, the second pixel luminance adjustment ratio, and the global luminance value of the input frame image for each pixel of the input frame image, and the final pixel luminance ratio is used to reduce the luminance of each pixel of the input frame image.
13. The image processing method according to claim 12, wherein the final pixel luminance ratio of each pixel of the input frame image is calculated by:
aclLR＝aclLGR+ωc×aclLRC+(1-ωc)×aclLRA
wherein aclLR is the final pixel luminance ratio, aclLGR is the basic pixel luminance ratio, aclLRA is the first pixel luminance adjustment ratio, aclLRC is the second pixel luminance adjustment ratio, and ω iscIs a weighted value between 0 and 1.
14. The image processing method according to claim 13, wherein the weight value ω iscThe calculation formula of (2) is as follows:
ωc＝aclwgratio×(1-Yavg)
wherein, aclwgratioIs a predetermined value, YavgThe global luminance value of the input frame image.
15. The image processing method as claimed in claim 1, wherein the image processing method is applied to an Organic Light Emitting Diode (OLED) display driving device.
16. The image processing method as claimed in claim 15, wherein the image processing method is used in an Automatic Current Limiting (ACL) in the oled display driving apparatus.
17. A computer storage medium comprising microcode for implementing an image processing method for auto current limiting, wherein the image processing method comprises:
reducing the overall brightness of the input frame image according to the global brightness value of the input frame image;
increasing the individual brightness of each pixel in the input frame image according to the absolute difference between the characteristic brightness value of each pixel and the global brightness value of the input frame image; and
increasing the individual luminance of each pixel according to the characteristic luminance value of each pixel and the global luminance value of the input frame image; wherein the method further comprises:
determining a first pixel brightness adjustment ratio and a second pixel brightness adjustment ratio according to a characteristic brightness value of each pixel in the input frame image and the global brightness value of the input frame image;
obtaining a final pixel brightness ratio corresponding to each pixel in the input frame image according to the first pixel brightness adjustment ratio, the second pixel brightness adjustment ratio, and the global brightness value of the input frame image; wherein,
the global brightness value is used to determine a ratio of the first pixel brightness adjustment ratio and the second pixel brightness adjustment ratio in calculating the final pixel brightness ratio,
the larger the global brightness value is, the larger the proportion of the first pixel brightness adjustment ratio is, and the smaller the proportion of the second pixel brightness adjustment ratio is; and
when the global brightness value is smaller, the proportion of the first pixel brightness adjustment ratio is smaller, and the proportion of the second pixel brightness adjustment ratio is larger.
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