Television terminal, method for converting HDR image into SDR image, and computer readable storage medium
Disclosed is a method for converting an HDR image into an SDR image. The method includes the following operations: acquiring, by a television terminal, input HDR image data, and processing, by the television terminal, the acquired HDR image data through a first normalization; linearizing, by the television terminal, the HDR image data processed through the first normalization; processing, by the television terminal, the linearized HDR image data through a second normalization; and converting, by the television terminal, the HDR image data processed through the second normalization into SDR image data with a supported format. The present disclosure further provides a television terminal and a computer readable storage medium. The present disclosure effectively avoids the technical problem of a poor image display effect caused by that the non-HDR receivers cannot show the HDR effect. The present disclosure enables non-HDR receivers to show the HDR effect and improves the image display effect.
1. A method for converting an HDR image into an SDR image, wherein the method comprises the following operations:
acquiring, by a television terminal, input HDR image data, and processing, by the television terminal, the acquired HDR image data through a first normalization;
linearizing, by the television terminal, the HDR image data processed through the first normalization;
processing, by the television terminal, the linearized HDR image data through a second normalization; and
converting, by the television terminal, the HDR image data processed through the second normalization into SDR image data with a supported format;
wherein the operation of “processing, by the television terminal, the acquired HDR image data through a first normalization” comprises:
determining, by the television terminal, a maximum coded value in the acquired HDR image data; and
processing, by the television terminal, all coded values in the acquired HDR image data through the first normalization and the maximum coded value, a value of the HDR image data processed through the first normalization has a range of [0, 1], wherein an equation for the first normalization is:
N=S HDR /(2 n −1), N is the value of the HDR image data processed through the first normalization, n is a bit depth of an image data signal, and S HDR is an input HDR signal quantization coded by Perceptual Quantizer.
2. The method of claim 1 , wherein the operation of “linearizing, by the television terminal, the HDR image data processed through the first normalization” comprises:
restoring, by the television terminal, the HDR image data processed through the first normalization to linear data before being coded, an equation for the restoring operation is:
L=(max[(N 1 /m2)−c1, 0]/(c2−c3N 1 /m2)) 1/m1 , wherein c1, c2, c3, m1 and m2 are constants.
3. The method of claim 2 , wherein the operation of “converting, by the television terminal, the HDR image data processed through the second normalization into SDR image data with a supported format” comprises:
acquiring, by the television terminal, a peak luminance value of a display; and
converting, by the television terminal, the HDR image data processed through the second normalization into the SDR image data with a format supported by the display based on the peak luminance value of the display, wherein an equation for the second normalization is:
L N =L/c m , wherein c m is a coded value of maximum luminance of the signal, and L is the linear data before being coded.
4. The method of claim 3 , wherein the second normalization is configured to normalize the coded value of maximum luminance of the signal, for normalizing the obtained value in a range of 0 to 1, and a minimum value is 0 and a maximum value is 1.
5. The method of claim 3 , wherein the method further comprises:
converting linear data in an HDR format into linear data in an SDR format based on a maximum peak luminance value of the display, and outputting SDR signal data, an equation for the converting operation is:
S SDR =(2 m −1)*M*L γ/ 2, wherein γ=1+aLog10(Y p /1000), Y p is the peak luminance value of the display (cd/m 2 ), a is a constant, m is a bit depth of an SDR signal, usually the SDR signal is 8 bits, i.e., m=8, and M has a range of 0 to 1 which is presented as an adjusting curve.
6. The method of claim 1 , wherein after the operation of “converting, by the television terminal, the HDR image data processed through the second normalization into SDR image data with a supported format”, the method further comprises:
outputting, by the television terminal, the converted SDR image data based on the format supported by the display.
7. The method of claim 1 , wherein after the operation of “converting, by the television terminal, the HDR image data processed through the second normalization into SDR image data with a supported format”, the method further comprises:
outputting, by the television terminal, the converted SDR image data based on the format supported by the display.
8. A television terminal, wherein the television terminal comprises a memory, a processor, and a program for converting an HDR image into an SDR image stored on the memory and executable on the processor, the program, when executed by the processor, implements the following operations:
acquiring input HDR image data, and processing the acquired HDR image data through a first normalization;
linearizing the HDR image data processed through the first normalization;
processing the linearized HDR image data through a second normalization; and
converting the HDR image data processed through the second normalization into SDR image data with a supported format;
wherein the operation of “processing the acquired HDR image data through a first normalization” comprises:
determining a maximum coded value in the acquired HDR image data; and
processing all coded values in the acquired HDR image data through the first normalization and the maximum coded value, a value of the HDR image data processed through the first normalization has a range of [0, 1], wherein an equation for the first normalization is:
N=S HDR /(2 n −1), N is the value of the HDR image data processed through the first normalization, n is a bit depth of an image data signal, and S HDR is an input HDR signal quantization coded by Perceptual Quantizer.
9. The television terminal of claim 8 , wherein the program, when executed by the processor, implements the following operations:
restoring the HDR image data processed through the first normalization to linear data before being coded, an equation for the restoring operation is:
L=(max[(N 1 /m2)−c1, 0]/(c2−c3N 1 /m2)) 1/m1 , wherein c1, c2, c3, m1 and m2 are constants.
10. The television terminal of claim 8 , wherein the program, when executed by the processor, implements the following operations:
acquiring a peak luminance value of a display; and
converting the HDR image data processed through the second normalization into the SDR image data with a format supported by the display based on the peak luminance value of the display, wherein an equation for the second normalization is:
L N =L/c m , wherein c m is a coded value of maximum luminance of the signal, and L is the linear data before being coded.
11. The television terminal of claim 10 , wherein the second normalization is configured to normalize the coded value of maximum luminance of the signal, for normalizing the obtained value in a range of 0 to 1, and a minimum value is 0 and a maximum value is 1.
12. The television terminal of claim 10 , wherein the program, when executed by the processor, implements the following operations:
converting linear data in an HDR format into linear data in an SDR format based on a maximum peak luminance value of the display, and outputting SDR signal data, an equation for the converting operation is:
S SDR =(2m−1)*M*L γ/ 2, wherein γ=1+aLog10(Y p /1000), Y p is the peak luminance value of the display (cd/m 2 ), a is a constant, m is a bit depth of an SDR signal, usually the SDR signal is 8 bits, i.e., m=8, and M has a range of 0 to 1 which is presented as an adjusting curve.
13. The television terminal of claim 8 , wherein the program, when executed by the processor, implements the following operations:
outputting the converted SDR image data based on the format supported by the display.
14. The television terminal of claim 8 , wherein the program, when executed by the processor, implements the following operations:
outputting the converted SDR image data based on the format supported by the display.
15. A non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium stores a program for converting an HDR image into an SDR image, the program, when executed by a processor, implements operations of the method for converting the HDR image into the SDR image, wherein the method comprises the following operations:
acquiring, by a television terminal, input HDR image data, and processing, by the television terminal, the acquired HDR image data through a first normalization;
linearizing, by the television terminal, the HDR image data processed through the first normalization;
processing, by the television terminal, the linearized HDR image data through a second normalization; and
converting, by the television terminal, the HDR image data processed through the second normalization into SDR image data with a supported format;
wherein the operation of “processing, by the television terminal, the acquired HDR image data through a first normalization” comprises:
determining, by the television terminal, a maximum coded value in the acquired HDR image data; and
processing, by the television terminal, all coded values in the acquired HDR image data through the first normalization and the maximum coded value, a value of the HDR image data processed through the first normalization has a range of [0, 1], wherein an equation for the first normalization is:
N=S HDR /(2 n −1), N is the value of the HDR image data processed through the first normalization, n is a bit depth of an image data signal, and S HDR is an input HDR signal quantization coded by Perceptual Quantizer.
16. The non-transitory computer readable storage medium of claim 15 , wherein the operation of “linearizing, by the television terminal, the HDR image data processed through the first normalization” comprises:
restoring, by the television terminal, the HDR image data processed through the first normalization to linear data before being coded, an equation for the restoring operation is:
L=(max[(N 1 /m2)−c1, 0]/(c2−c3N 1 /m2)) 1/m1 , wherein c1, c2, c3, m1 and m2 are constants.
17. The non-transitory computer readable storage medium of claim 15 , wherein after the operation of “converting, by the television terminal, the HDR image data processed through the second normalization into SDR image data with a supported format”, the method further comprises:
outputting, by the television terminal, the converted SDR image data based on the format supported by the display.