IP Library › Granted Patent US 12671848
Granted Patent B2
US 12671848 · App. 18/602,449 · Granted Jun 30, 2026

Pixel value mapping method

Inventors: Zhiwei Huang (Hangzhou, CN); Jianhua Chen (Hangzhou, CN); Yan Ye (San Diego, CA)
Assignee: Alibaba (China) Co., Ltd.
H04N19/85H04N19/182
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Quick Facts
Patent No.
US 12671848
App. No.
18/602,449
Granted
Jun 30, 2026
Kind
B2
Abstract

Embodiments of the present disclosure provide a pixel value mapping method, including: determining a to-be-processed image and a mapping table corresponding to the to-be-processed image; performing a table lookup on pixel values of multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain mapped values each corresponding to a pixel of the multiple pixels; and determining a mapped image corresponding to the to-be-processed image according to the mapped values obtained based on the table lookup.

Claims (86)

1 . A method for encoding a video sequence, the method comprising:

receiving a video sequence; and

encoding the video sequence by:

determining a to-be-processed image and a mapping table corresponding to the to-be-processed image;

performing a table lookup on pixel values of multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain mapped values each corresponding to a pixel of the multiple pixels; and

determining a mapped image corresponding to the to-be-processed image according to the mapped values obtained based on the table lookup;

comparing the pixel values of the multiple pixels to determine a maximum pixel value and a minimum pixel value; wherein performing the table lookup on the pixel values of the multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

determining a first sub-table of a pixel value range corresponding to the maximum pixel value and the minimum pixel value from the mapping table; and

performing the table lookup on the pixel values of the multiple pixels according to the first sub-table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels.

2 . The method according to claim 1 , wherein the number of the multiple pixels is m times of a degree of parallelism of the table lookup, m being a positive integer, and performing the table lookup on the pixel values of the multiple pixels according to the first sub-table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

dividing the pixel values of the multiple pixels into m groups of to-be-queried pixel values according to the degree of parallelism; and

performing a NEON-based parallel table lookup on the to-be-queried pixel values according to the first sub-table by groups to obtain the mapped values each corresponding to a pixel of the multiple pixels.

3 . The method according to claim 2 , wherein performing the NEON-based parallel table lookup on the to-be-queried pixel values according to the first sub-table by groups to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

segmenting the first sub-table to obtain multiple second sub-tables;

performing the NEON-based parallel table lookup on the to-be-queried pixel values according to the multiple second sub-tables by groups to obtain multiple sets of query results corresponding to respective groups of the to-be-queried pixel values; and

merging the multiple sets of query results to obtain respective mapped values corresponding to respective groups of the to-be-queried pixel values.

4 . The method according to claim 1 , wherein comparing the pixel values of the multiple pixels to determine the maximum pixel value and the minimum pixel value comprises:

initializing a maximum value register and a minimum value register, where the number of pixel values stored in the maximum value register or the minimum value register is i, and the number of the multiple pixels is n times the number of the pixel values i, n being a positive integer;

dividing the pixel values of the multiple pixels into n groups of to-be-compared pixel values, where each group of the to-be-compared pixel values comprises i pixel values;

comparing each group of the to-be-compared pixel values with the pixel values stored in the maximum value register bit by bit, and updating the i pixel values stored in the maximum value register according to the maximum value in the comparison result;

comparing each group of the to-be-compared pixel values with the pixel values stored in the minimum value register bit by bit, and updating the i pixel values stored in the minimum value register according to the minimum value in the comparison result; and

determining the maximum pixel value from the i pixel values stored in the maximum value register, and determining the minimum pixel value from the i pixel values stored in the minimum value register.

5 . The method according to claim 1 , wherein determining the first sub-table of the pixel value range corresponding to the maximum pixel value and the minimum pixel value from the mapping table comprises:

determining the number of pixel values of the first sub-table according to a difference between the maximum pixel value and the minimum pixel value; and

determining the first sub-table from the mapping table according to the number of pixel values starting from the minimum pixel value.

6 . The method according to claim 1 , wherein performing the table lookup on the pixel values of the multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

segmenting the mapping table to obtain multiple third sub-tables;

performing parallel table lookups on the pixel values of the multiple pixels in the multiple third sub-tables respectively to obtain multiple sets of query results; and

merging the multiple sets of query results to obtain respective mapped values each corresponding to a pixel of the multiple pixels.

7 . The method according to claim 1 , further comprising:

storing a bitstream that is generated based on the encoding.

8 . A method for decoding a bitstream, the method comprising:

receiving a bitstream; and

decoding the bitstream to generate a video sequence, the decoding comprising:

determining a to-be-processed image and a mapping table corresponding to the to-be-processed image;

performing a table lookup on pixel values of multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain mapped values each corresponding to a pixel of the multiple pixels; and

determining a mapped image corresponding to the to-be-processed image according to the mapped values obtained based on the table lookup;

comparing the pixel values of the multiple pixels to determine a maximum pixel value and a minimum pixel value; wherein performing the table lookup on the pixel values of the multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

determining a first sub-table of a pixel value range corresponding to the maximum pixel value and the minimum pixel value from the mapping table; and

performing the table lookup on the pixel values of the multiple pixels according to the first sub-table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels.

9 . The method according to claim 8 , wherein the number of the multiple pixels is m times of a degree of parallelism of the table lookup, m being a positive integer, and performing the table lookup on the pixel values of the multiple pixels according to the first sub-table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

dividing the pixel values of the multiple pixels into m groups of to-be-queried pixel values according to the degree of parallelism; and

performing a NEON-based parallel table lookup on the to-be-queried pixel values according to the first sub-table by groups to obtain the mapped values each corresponding to a pixel of the multiple pixels.

10 . The method according to claim 9 , wherein performing the NEON-based parallel table lookup on the to-be-queried pixel values according to the first sub-table by groups to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

segmenting the first sub-table to obtain multiple second sub-tables;

performing the NEON-based parallel table lookup on the to-be-queried pixel values according to the multiple second sub-tables by groups to obtain multiple sets of query results corresponding to respective groups of the to-be-queried pixel values; and

merging the multiple sets of query results to obtain respective mapped values corresponding to respective groups of the to-be-queried pixel values.

11 . The method according to claim 8 , wherein comparing the pixel values of the multiple pixels to determine the maximum pixel value and the minimum pixel value comprises:

initializing a maximum value register and a minimum value register, where the number of pixel values stored in the maximum value register or the minimum value register is i, and the number of the multiple pixels is n times the number of the pixel values i, n being a positive integer;

dividing the pixel values of the multiple pixels into n groups of to-be-compared pixel values, where each group of the to-be-compared pixel values comprises i pixel values;

comparing each group of the to-be-compared pixel values with the pixel values stored in the maximum value register bit by bit, and updating the i pixel values stored in the maximum value register according to the maximum value in the comparison result;

comparing each group of the to-be-compared pixel values with the pixel values stored in the minimum value register bit by bit, and updating the i pixel values stored in the minimum value register according to the minimum value in the comparison result; and

determining the maximum pixel value from the i pixel values stored in the maximum value register, and determining the minimum pixel value from the i pixel values stored in the minimum value register.

12 . The method according to claim 8 , wherein determining the first sub-table of the pixel value range corresponding to the maximum pixel value and the minimum pixel value from the mapping table comprises:

determining the number of pixel values of the first sub-table according to a difference between the maximum pixel value and the minimum pixel value; and

determining the first sub-table from the mapping table according to the number of pixel values starting from the minimum pixel value.

13 . The method according to claim 8 , wherein performing the table lookup on the pixel values of the multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

segmenting the mapping table to obtain multiple third sub-tables;

performing parallel table lookups on the pixel values of the multiple pixels in the multiple third sub-tables respectively to obtain multiple sets of query results; and

merging the multiple sets of query results to obtain respective mapped values each corresponding to a pixel of the multiple pixels.

14 . A method for signaling a bitstream, the method comprising:

receiving a video sequence;

encoding the video sequence by:

determining a to-be-processed image and a mapping table corresponding to the to-be-processed image;

performing a table lookup on pixel values of multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain mapped values each corresponding to a pixel of the multiple pixels; and

determining a mapped image corresponding to the to-be-processed image according to the mapped values obtained based on the table lookup;

comparing the pixel values of the multiple pixels to determine a maximum pixel value and a minimum pixel value; wherein performing the table lookup on the pixel values of the multiple pixels in the to-be-processed image according to the mapping table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

determining a first sub-table of a pixel value range corresponding to the maximum pixel value and the minimum pixel value from the mapping table; and

performing the table lookup on the pixel values of the multiple pixels according to the first sub-table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels; and

signaling a bitstream that is generated based on the encoding.

15 . The method according to claim 14 , wherein the number of the multiple pixels is m times of a degree of parallelism of the table lookup, m being a positive integer, and performing the table lookup on the pixel values of the multiple pixels according to the first sub-table in parallel to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

dividing the pixel values of the multiple pixels into m groups of to-be-queried pixel values according to the degree of parallelism; and

performing a NEON-based parallel table lookup on the to-be-queried pixel values according to the first sub-table by groups to obtain the mapped values each corresponding to a pixel of the multiple pixels.

16 . The method according to claim 15 , wherein performing the NEON-based parallel table lookup on the to-be-queried pixel values according to the first sub-table by groups to obtain the mapped values each corresponding to a pixel of the multiple pixels comprises:

segmenting the first sub-table to obtain multiple second sub-tables;

performing the NEON-based parallel table lookup on the to-be-queried pixel values according to the multiple second sub-tables by groups to obtain multiple sets of query results corresponding to respective groups of the to-be-queried pixel values; and

merging the multiple sets of query results to obtain respective mapped values corresponding to respective groups of the to-be-queried pixel values.

17 . The method according to claim 14 , wherein comparing the pixel values of the multiple pixels to determine the maximum pixel value and the minimum pixel value comprises:

initializing a maximum value register and a minimum value register, where the number of pixel values stored in the maximum value register or the minimum value register is i, and the number of the multiple pixels is n times the number of the pixel values i, n being a positive integer;

dividing the pixel values of the multiple pixels into n groups of to-be-compared pixel values, where each group of the to-be-compared pixel values comprises i pixel values;

comparing each group of the to-be-compared pixel values with the pixel values stored in the maximum value register bit by bit, and updating the i pixel values stored in the maximum value register according to the maximum value in the comparison result;

comparing each group of the to-be-compared pixel values with the pixel values stored in the minimum value register bit by bit, and updating the i pixel values stored in the minimum value register according to the minimum value in the comparison result; and

determining the maximum pixel value from the i pixel values stored in the maximum value register, and determining the minimum pixel value from the i pixel values stored in the minimum value register.

18 . The method according to claim 14 , wherein determining the first sub-table of the pixel value range corresponding to the maximum pixel value and the minimum pixel value from the mapping table comprises:

determining the number of pixel values of the first sub-table according to a difference between the maximum pixel value and the minimum pixel value; and

determining the first sub-table from the mapping table according to the number of pixel values starting from the minimum pixel value.