CN117319621A - Control device and control method - Google Patents

Control device and control method Download PDF

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Publication number
CN117319621A
CN117319621A CN202311319103.XA CN202311319103A CN117319621A CN 117319621 A CN117319621 A CN 117319621A CN 202311319103 A CN202311319103 A CN 202311319103A CN 117319621 A CN117319621 A CN 117319621A
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CN
China
Prior art keywords
eetf
image
circuit
input
brightness
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Pending
Application number
CN202311319103.XA
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Chinese (zh)
Inventor
诸葛慧
苏峻贤
和家璞
李启祯
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AU Optronics Corp
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AU Optronics Corp
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Publication of CN117319621A publication Critical patent/CN117319621A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/77—Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/42—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/68—Circuits for processing colour signals for controlling the amplitude of colour signals, e.g. automatic chroma control circuits

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)

Abstract

A control device is disclosed. The control device comprises an input circuit, a processor and an output circuit. The input circuit is used for receiving an input image. The processor is coupled to the input circuit. The processor comprises an EETF (electric transfer function) processing circuit, a signal compression circuit and an EOTF (electric transfer function) processing circuit. The EETF processing circuit is used for EETF converting the input image to generate an EETF converted image. The signal compression circuit is used for compressing the EETF-converted image so as to compress the EETF-converted image to the brightness upper limit value and generate the compressed image. The EOTF processing circuit is used for performing EOTF conversion on the compressed image to generate an output image. The output circuit is used for transmitting the output image to the display device.

Description

Control device and control method
Technical Field
The embodiments described in this disclosure relate to a control apparatus and a control method, and more particularly, to a control apparatus and a control method for high dynamic range video (HDR, high dynamic range).
Background
Almost all products with screens on the market not only emphasize the image quality and definition of the display, but also show excellent color reproduction capability. High Dynamic Range (HDR) is a term often used to describe viewing experiences on displays, and the addition of HDR technology to display products allows greater contrast between shades and improves color rendering and brightness, making films and images look better, either in whole or in detail.
The input format of a general HDR is divided into three types of RGB color space, YCbCr color space, ICtCp color space. The HDR film contains relevant luminance information when making the film, which is recorded in the relay data (Metadata), and the display device must capture the information when viewing the HDR film, restore the HDR film by EETF (electronic transfer function), and map the film luminance range to the luminance range of the user display, so as to faithfully present the director's shot content. However, the YCbCr color space is not a uniform color space, which will cause reduced color distortion, resulting in color shift. How to solve the color shift after conversion is one of the problems to be solved in the field.
Disclosure of Invention
One aspect of the present disclosure is to provide a control device. The control device comprises an input circuit, a processor and an output circuit. The input circuit is used for receiving an input image. The processor is coupled to the input circuit. The processor comprises an EETF (electric transfer function) processing circuit, a signal compression circuit and an EOTF (electric transfer function) processing circuit. The EETF processing circuit is used for EETF converting the input image to generate an EETF converted image. The signal compression circuit is coupled to the EETF processing circuit for compressing the EETF-converted image, so as to compress the EETF-converted image to the brightness upper limit value and generate a compressed image. The EOTF processing circuit is coupled to the signal compression circuit and is used for performing EOTF conversion on the compressed image to generate an output image. The output circuit is coupled to the processor and used for transmitting the output image to the display device.
Another aspect of the present disclosure is to provide a control method. The control method is suitable for the control device, wherein the control method comprises the following steps: receiving an input image; EETF conversion is carried out on the input image so as to generate an EETF converted image; compressing the EETF-converted image to compress the EETF-converted image to a brightness upper limit value and generate a compressed image; EOTF conversion is carried out on the compressed image so as to generate an output image; and transmitting the output image to the display device.
Drawings
The foregoing and other objects, features, advantages and embodiments of the present disclosure will be apparent from the following description of the drawings in which:
FIG. 1 is a schematic diagram of a control device according to some embodiments of the present disclosure;
FIG. 2 is a schematic diagram of a control method according to some embodiments of the present disclosure;
FIG. 3 is a schematic diagram of a control flow depicted in accordance with some embodiments of the present disclosure;
FIG. 4 is a schematic diagram of a brightness adjustment according to some embodiments of the present disclosure; and
fig. 5 is a diagram of experimental data illustrating a compression process according to some embodiments of the present disclosure.
Wherein, the reference numerals:
100 control device
110 input circuit
130 processor
131 preprocessing circuit
EETF processing circuit
134 signal compression circuit
EOTF processing circuit 136
137 post-processing circuit
150 output circuit
800 signal source device
900 display device
200 control method
S210, S230, S250, S270, S290 step
300 control flow
310,330,340,350,370,390 square block
Detailed Description
The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Elements and configurations in specific examples are used in the following discussion to simplify the present disclosure. Any exemplifications set out herein are for illustrative purposes only, and are not intended to limit the scope and meaning of the invention or its exemplifications in any manner. Moreover, the present disclosure may repeat reference numerals and/or letters in the various examples, which are for the purpose of simplicity and illustration, and does not in itself dictate a relationship between the various embodiments and/or configurations discussed below.
The words (terms) used throughout this specification and claims have the ordinary meaning of each word used in this field, in the disclosure herein, and in the special context, unless otherwise specifically noted. Certain terms used to describe the disclosure are discussed below, or elsewhere in this specification, to provide additional guidance to those skilled in the art in describing the disclosure.
As used herein, "coupled" or "connected" may mean that two or more elements are in direct physical or electrical contact with each other, or in indirect physical or electrical contact with each other, and "coupled" or "connected" may also mean that two or more elements are in operation or action with each other.
The terms first, second, third, etc. are used herein to describe various elements, components, regions, layers and/or blocks. These elements, components, regions, layers and/or blocks should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another. Accordingly, a first element, component, region, layer and/or section discussed below could be termed a second element, component, region, layer and/or section without departing from the spirit of the present invention. As used herein, the term "and/or" includes any combination of one or more of the listed associated items. Reference in this disclosure to "and/or" means any, all, or any combination of at least one of the listed elements.
Please refer to fig. 1. Fig. 1 is a schematic diagram of a control device 100 according to some embodiments of the present disclosure. As shown in fig. 1, the control device 100 includes an input circuit 110, a processor 130, and an output circuit 150. In connection, the input circuit 110 is coupled to the processor 130, and the processor 130 is coupled to the output circuit 150.
In some embodiments, the processor 130 as shown in fig. 1 includes an EETF (electric transfer function) processing circuit 132, a signal compression circuit 134, and an EOTF (electro-optical transfer function) processing circuit 136. In connection, the EETF processing circuit 132 is coupled to the signal compressing circuit 134, and the signal compressing circuit 134 is coupled to the EOTF processing circuit 136.
In some embodiments, the processor 130 as shown in fig. 1 further includes a preprocessing circuit 131 and a post-processing circuit 137. The preprocessing circuit 131 is coupled to the EETF processing circuit 132, and the post-processing circuit 137 is coupled to the EOTF processing circuit 136.
The detailed operation of the control device 100 of fig. 1 will be described below with reference to fig. 2 to 3.
Please refer to fig. 2. FIG. 2 is a schematic diagram of a control method 200 according to some embodiments of the present disclosure. As shown in fig. 2, the control method 200 includes steps S210 to S290.
In step S210, an input image is received. Please refer to fig. 1. In some embodiments, step S210 is performed by the input circuit 110 shown in fig. 1. In some embodiments, the signal source device 800 generates an input image and transmits the input image to the input circuit 110.
Please refer to fig. 3. FIG. 3 is a schematic diagram of a control flow 300 according to some embodiments of the present disclosure. As shown in block 310 of FIG. 3, the format of the input image may include RGB color parameters, YCbCr color parameters, or ICtCp color parameters.
In some embodiments, when the input image includes RGB color parameters, the preprocessing circuit 131 shown in fig. 1 converts the RGB color parameters into YCbCr color parameters, and then sends the input image including the YCbCr color parameters to the EETF processing circuit 132. In other embodiments, when the input image includes YCbCr color parameters or ICtCP color parameters, the preprocessing circuit 131 converts the color format of the input image into a 4:4:4 chroma sampling format, and then sends the color-format-converted input image to the EETF processing circuit 132.
Please refer back to fig. 2. In step S230, the input image is subjected to EETF conversion to generate an EETF converted image. In some embodiments, step S230 is performed by the EETF processing circuit 132 shown in fig. 1.
Please refer to fig. 3. In block 330, EETF is converted for the input image. The input image containing YCbCr color parameters still contains YCbCr color parameters after EETF conversion, and the input image containing ICtCP color parameters still contains ICtCP color parameters after EETF conversion.
In some embodiments, the EETF processing circuit 132 performs conversion according to the following EETF functions. Wherein (Y' 1 ,Cb′ 1 ,Cr′ 1 ) For the YCbCr color parameters input to EETF processing circuit 132, and (Y' 2 ,Cb′ 2 ,Cr′ 2 ) YCbCr color parameters are output for the EETF processing circuit 132.
Y′ 2 ＝EETF(Y′ 1 )。
In other embodiments, the EETF processing circuit 132 performs conversion according to the following EETF functions. Wherein (I' 1 ,Ct 1 ,Cp 1 ) For ICtCp color parameters input to EETF processing circuit 132, and (I' 2 ,Ct 2 ,Cp′ 2 ) The ICtCp color parameters output for the EETF processing circuit 132.
I′ 2 ＝EETF(I′ 1 )。
As can be seen from the EETF conversion function, only Y color parameters are converted during EETF conversion, and Cb color parameters and Cr color parameters are adjusted in a fixed ratio according to the input/output ratio of Y color parameters. This may cause a partial color transition to a brightness greater than the white of the display device 900 as depicted in fig. 1. In this way, the color shift of the converted color occurs, and the embodiments of the present invention solve this problem.
Please continue to refer to fig. 3. In some embodiments, step S230 further includes a block 340. After the EETF conversion, the EETF processing circuit 132 of the processor 130 shown in fig. 1 is further configured to perform color parameter conversion on the input image in a 3×3 matrix to convert YCbCr color parameters into RGB color parameters and convert ICtCp color parameters into LMS color parameters.
Please refer back to fig. 2. In step S250, the EETF converted image is compressed to compress the EETF converted image to the luminance upper limit value, and a compressed image is generated. In some embodiments, step S250 is performed by the signal compressing circuit 134 shown in fig. 1.
In some embodiments, the step S250 further includes reducing the luminance of the EETF converted image when the luminance of the EETF converted image is higher than the luminance threshold. In some embodiments, the brightness threshold is at least 0.5 times the brightness upper limit. In some embodiments, the luminance includes RGB color parameters or LMS color parameters.
In some embodiments, the compression function of the signal compression circuit 134 is a linear function. Please refer to fig. 4. Fig. 4 is a schematic diagram illustrating a brightness adjustment according to some embodiments of the present disclosure. RGBin in fig. 4 is a color parameter input to the signal compressing circuit 134, and rgbeout is a color parameter output from the signal compressing circuit 134. Lmax is the luminance upper limit value. Sr is the ratio between the brightness upper limit value and the brightness threshold value. Lmax Sr is the luminance threshold. RGBmax is the maximum value among the color parameters input to the signal compression circuit 134.
As shown in fig. 4, the color parameters below the brightness threshold remain the original values, and the brightness of the color parameters above the brightness threshold is reduced. RGB (nL) and RGB (nH) in fig. 4 are conversion functions that are not compressed by the signal compression circuit 134. Rgbaclip (nL) and rgbaclip (nH) are conversion functions compressed by the signal compression circuit 134.
In some embodiments, the signal compression circuit 134 compresses according to the following conversion function.
nL＝find(RGB<Lmax×Sr)。
nH＝find(RGB≥Lmax×Sr)。
RGBmax＝max(max(RGB))。
RGBclip(nL)＝RGB(nL)。
RGBclip(nH)
＝(Lmax×Sr)+((RGB(nH)-Lmax×Sr)/(RGBmax-Lmax×Sr))×((1-Sr)×Lmax)。
As shown in fig. 4, after the compression by the conversion function, the original values of the color parameters below the brightness threshold are maintained, and the brightness of the color parameters above the brightness threshold is reduced to be within the brightness upper limit.
Please refer to fig. 3. Step S250 includes block 350 depicted in fig. 3. As depicted in fig. 3. When the color parameters input to the signal compressing circuit 134 are RGB, the color parameters output by the signal compressing circuit 134 are RGB. When the color parameter input to the signal compression circuit 134 is LMS, the color parameter output by the signal compression circuit 134 is LMS. The compression method regarding the LMS color parameters is similar to the compression method of the RGB color parameters and will not be described in detail herein.
The compression function as depicted in fig. 4 is a linear function. However, various compression functions are within embodiments of the present invention. For example, the compression function may be a stepwise linear function.
It should be noted that if the compression function is a nonlinear function, the calculation amount is too large. In addition, the problem of color gradation becomes worse as the luminance threshold value is closer to the luminance upper limit value.
Please refer back to fig. 2. In step S270, EOTF conversion is performed on the compressed image to generate an output image. In some embodiments, step S270 is performed by the EOTF processing circuit 136 in fig. 1.
Please refer to fig. 3. Step S270 includes block 370 of fig. 3. As shown in fig. 3, when the color parameters input to the EOTF processing circuit 136 are RGB, the color parameters output by the EOTF processing circuit 136 are RGB. When the color parameter input to the EOTF processing circuit 136 is LMS, the color parameter output by the EOTF processing circuit 136 is LMS. Various EOTF conversion functions are within the present embodiments. An embodiment of EOTF conversion function will be presented below, but the embodiment of the present invention is not limited thereto.
An implementation of the EOTF conversion function is as follows:
the perceptually quantized inverse EOTF transfer function is as follows:
wherein E' is a nonlinear signal value in the range [0,1 ];
F D to display brightness, unit cd/m 2 ；
Y＝F D 10000, which is a nonlinear display value, in the range of 0,1]When y=1 represents 10000cd/m 2 Is a display luminance peak value;
in some embodiments, step S270 further includes performing color gamut conversion of the 3×3 matrix by the post-processing circuit 137 in fig. 1 to generate an output image. Referring to fig. 3, as shown in block 390 of fig. 3, when the color parameters input to the post-processing circuit 137 are RGB, the color parameters output by the post-processing circuit 137 are RGB. When the color parameter input to the post-processing circuit 137 is LMS, the color parameter output by the post-processing circuit 137 is RGB.
One color gamut conversion function in the case where the color parameters input to the post-processing circuit 137 are RGB is illustrated below, however, the embodiment is not limited thereto.
Above-mentionedFor the color parameters input to the post-processing circuit 137, < >>Color parameters output for post-processing circuitry 137. [ M ] Display ] -1 To correspond to the conversion matrix of the display device 900 in fig. 1, [ M ] Scene ]Is a transformation matrix corresponding to the input content metadata of the signal source device 800 in fig. 1.
Please refer back to fig. 2. In step S290, the output image is transmitted to the display device. In some embodiments, step S290 is performed by the post-processing circuit 137 in fig. 1, and the output image is transmitted to the display device 900 in fig. 1 to play the image.
Please refer to fig. 5. Fig. 5 is a diagram of experimental data illustrating a compression process according to some embodiments of the present disclosure. Fig. 5 shows the Input to the signal compression circuit 134 and the Output of the signal compression circuit 134 at different ratios Sr. As can be seen from fig. 5, when the value of the proportion Sr is high, the problem of color overlay is more serious. On the other hand, when the value of the proportion Sr is low, the brightness of the color may be suppressed, possibly resulting in excessive darkness of the image.
As can be seen from the above embodiments of the present disclosure, the embodiments of the present disclosure provide a control device and a control method, by adding a signal compression circuit after the EETF processing circuit and before the EOTF processing circuit, to compress the color parameter portion exceeding the white upper limit of the display into the upper limit, so as to prevent the converted color from exceeding the white upper limit of the display, and thus the user can obtain a better viewing experience.
In addition, the above examples include exemplary steps in a sequence, but the steps need not be performed in the order shown. It is within the contemplation of the present disclosure that the steps be executed in a different order. It is contemplated that steps may be added, substituted, altered in order and/or omitted within the spirit and scope of the embodiments of the disclosure.
While the present disclosure has been described with reference to the embodiments, it should be understood that the invention is not limited thereto, but may be variously modified and modified by those skilled in the art without departing from the spirit and scope of the present disclosure, and the scope of the present disclosure is accordingly defined by the appended claims.

Claims (10)

1. A control apparatus, comprising:
an input circuit for receiving an input image;
a processor coupled to the input circuit, wherein the processor comprises:
an EETF processing circuit for EETF-converting the input image to generate an EETF-converted image;
the signal compression circuit is coupled to the EETF processing circuit and used for compressing the EETF converted image so as to compress the EETF converted image into a brightness upper limit value and generate a compressed image; and
an EOTF processing circuit, coupled to the signal compression circuit, for performing EOTF conversion on the compressed image to generate an output image; and
an output circuit, coupled to the processor, for transmitting the output image to a display device.
2. The control apparatus of claim 1, wherein the signal compression circuit is further configured to reduce the luminance of the EETF-converted image when a luminance of the EETF-converted image is higher than a luminance threshold.
3. The control device of claim 2, wherein the brightness threshold is at least 0.5 times the brightness upper limit.
4. The control apparatus of claim 2, wherein the signal compression circuit is further configured to reduce the brightness of the EETF converted image by a linear function.
5. The control device of claim 2 wherein the luminance includes an RGB color parameter or an LMS color parameter.
6. A control method, suitable for a control device, wherein the control method comprises:
receiving an input image;
EETF converting the input image to generate an EETF converted image;
compressing the EETF-converted image to compress the EETF-converted image to a brightness upper limit value and generate a compressed image;
EOTF conversion is carried out on the compressed image so as to generate an output image; and
transmitting the output image to a display device.
7. The control method of claim 6, further comprising:
when a brightness of the EETF-converted image is higher than a brightness threshold, the brightness of the EETF-converted image is reduced.
8. The control method of claim 7, wherein the brightness threshold is at least 0.5 times the brightness upper limit.
9. The control method of claim 7, further comprising;
the brightness of the EETF-converted image is reduced by a linear function.
10. The control method of claim 7, wherein the luminance includes an RGB color parameter or an LMS color parameter.
CN202311319103.XA 2023-04-26 2023-10-12 Control device and control method Pending CN117319621A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
TW112115606 2023-04-26
TW112115606 2023-04-26

Publications (1)

Publication Number Publication Date
CN117319621A true CN117319621A (en) 2023-12-29

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Application Number Title Priority Date Filing Date
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