SEI message for film grain synthesis mask

1 . A method for video decoding, the method comprising:

obtaining video data comprising at least one coded picture;

reconstructing a coded picture associated in the video data with a film grain characteristics SEI message, a first sample, a second sample, a third alpha map sample, and a fourth alpha map sample, wherein after reconstruction the first sample and the third alpha map sample, and the second sample and the fourth alpha map sample are spatially co-located, the film grain characteristics SEI message comprises an “for region” syntax indicating:

any of partial and complete co-location of regions indicated by ones of the first sample, the second sample, the third alpha map sample, and the fourth alpha map sample, and

each of an “fgr_region_left[i]” value, an “fgr_region_top[i]” value, an “fgr_region_width[i]” value, and an “fgr_region_height[i]” value, of which the “fgr_region_left[i]” value, the “fgr_region_top[i]” value, the “fgr_region_width[i]” value, and the “fgr_region_height[i]” value represent coordinates of a top-left corner and a width and height of a bounding box of an i-th region of the coded picture;

applying film grain synthesis to the first sample based on a first value of the third sample; and

determining to not apply film grain syntheses to the second sample based on a second value of the fourth sample, wherein the first value and second value are different from each other.

2 . The method according to claim 1 , wherein

the “fgr_region_left[i]” value represents a first range of 0 to a PicWidthInLumaSamples values minus 1, inclusive,

the “fgr_region_top[i]” value represents a second range of 0 to a PicHeightInLumaSamples value minus 1, inclusive,

the “fgr_region_width[i]” value represents a third range of 0 to the PicWidthInLumaSamples value minus the “fgr_region_left[i]” value, and

the “fgr_region_height[i]” value represents a fourth range of 0 to the PicHeightInLumaSamples minus the “fgr_region_top[i]” value, inclusive.

3 . The method according to claim 1 ,

wherein the coded picture is further associated in the video data with an alpha channel information SEI message which indicates the third alpha map sample and the fourth alpha map sample, and

wherein the alpha channel information SEI message indicates alpha channel sample values and post-processing applied to decoded alpha planes coded in auxiliary pictures of type AUX_ALPHA and one or more associated primary pictures.

4 . The method according to claim 1 ,

wherein the coded picture is further associated in the video data with an alpha channel information SEI message which indicates the third alpha map sample and the fourth alpha map sample, and

wherein the alpha channel information SEI message having a predetermined value indicates that a simulated film grain value at a same position and color component sample is to be multiplied by interpretation sample values of a decoded auxiliary picture prior to calculating film grain values.

5 . The method according to claim 4 ,

wherein the value is an integer that is 3.

6 . The method according to claim 1 ,

wherein the film grain characteristics SEI message identifies a blending mode used to blend simulated film grain with input images.

7 . The method according to claim 6 ,

wherein the grain characteristics SEI message further identifies a weighting of the film grain synthesis to by applied to the first sample.

8 . A method for video encoding, the method comprising:

obtaining video data comprising at least one picture; and

encoding the video data such that reconstructing the at least one picture comprises reconstructing the at least one picture as associated in the video data with a film grain characteristics SEI message, a first sample, a second sample, a third alpha map sample, and a fourth alpha map sample, wherein after reconstruction the first sample and the third alpha map sample, and the second sample and the fourth alpha map sample are spatially co-located, the film grain characteristics SEI message comprises an “for region” syntax indicating:

any of partial and complete co-location of regions indicated by ones of the first sample, the second sample, the third alpha map sample, and the fourth alpha map sample, and

each of an “fgr_region_left[i]” value, an “fgr_region_top[i]” value, an “fgr_region_width[i]” value, and an “fgr_region_height[i]” value, of which the “fgr_region_left[i]” value, the “fgr_region_top[i]” value, the “fgr_region_width[i]” value, and the “fgr_region_height[i]” value represent coordinates of a top-left corner and a width and height of a bounding box of an i-th region of the coded picture;

wherein reconstructing the at least one picture further comprises applying film grain synthesis to the first sample based on a first value of the third sample and determining to not apply film grain syntheses to the second sample based on a second value of the fourth sample, wherein the first value and second value are different from each other.

9 . The method according to claim 8 , wherein

the “fgr_region_left[i]” value represents a first range of 0 to a PicWidthInLumaSamples values minus 1, inclusive,

the “fgr_region_top[i]” value represents a second range of 0 to a PicHeightInLumaSamples value minus 1, inclusive,

the “fgr_region_width[i]” value represents a third range of 0 to the PicWidthInLumaSamples value minus the “fgr_region_left[i]” value, and

the “fgr_region_height[i]” value represents a fourth range of 0 to the PicHeightInLumaSamples minus the “fgr_region_top[i]” value, inclusive.

10 . The method according to claim 8 ,

wherein encoding the video data comprises associating the picture in the video data with an alpha channel information SEI message which indicates the third alpha map sample and the fourth alpha map sample, and

wherein the alpha channel information SEI message indicates alpha channel sample values and post-processing applied to decoded alpha planes coded in auxiliary pictures of type AUX_ALPHA and one or more associated primary pictures.

11 . The method according to claim 8 ,

wherein encoding the video data comprises associating the picture in the video data with an alpha channel information SEI message which indicates the third alpha map sample and the fourth alpha map sample, and

wherein the alpha channel information SEI message having a predetermined value indicates that a simulated film grain value at a same position and color component sample is to be multiplied by interpretation sample values of a decoded auxiliary picture prior to calculating film grain values.

12 . The method according to claim 11 ,

wherein the value is an integer that is 3.

13 . The method according to claim 8 ,

wherein the film grain characteristics SEI message identifies a blending mode used to blend simulated film grain with input images.

14 . The method according to claim 13 ,

wherein the grain characteristics SEI message further identifies a weighting of the film grain synthesis to by applied to the first sample.

15 . A method of encoding visual media data, the method comprising:

generating a bitstream of the visual media data according to a an encoding process comprising:

encoding a coded picture associated in video data with a film grain characteristics SEI message, a first sample, a second sample, a third alpha map sample, and a fourth alpha map sample, wherein after reconstruction the first sample and the third alpha map sample, and the second sample and the fourth alpha map sample are spatially co-located, the film grain characteristics SEI message comprises an “for region” syntax indicating:

any of partial and complete co-location of regions indicated by ones of the first sample, the second sample, the third alpha map sample, and the fourth alpha map sample, and

each of an “fgr_region_left[i]” value, an “fgr_region_top[i]” value, an “fgr_region_width[i]” value, and an “fgr_region_height[i]” value, of which the “fgr_region_left[i]” value, the “fgr_region_top[i]” value, the “fgr_region_width[i]” value, and the “fgr_region_height[i]” value represent coordinates of a top-left corner and a width and height of a bounding box of an i-th region of the coded picture;

applying film grain synthesis to the first sample based on a first value of the third sample; and

determining to not apply film grain syntheses to the second sample based on a second value of the fourth sample, wherein the first value and second value are different from each other.

16 . The method according to claim 15 , wherein

the “fgr_region_left[i]” value represents a first range of 0 to a PicWidthInLumaSamples values minus 1, inclusive,

the “fgr_region_top[i]” value represents a second range of 0 to a PicHeightInLumaSamples value minus 1, inclusive,

the “fgr_region_width[i]” value represents a third range of 0 to the PicWidthInLumaSamples value minus the “fgr_region_left[i]” value, and

the “fgr_region_height[i]” value represents a fourth range of 0 to the PicHeightInLumaSamples minus the “fgr_region_top[i]” value, inclusive.

17 . The method according to claim 15 ,

wherein the coded picture is further associated in the video data with an alpha channel information SEI message which indicates the third alpha map sample and the fourth alpha map sample, and

wherein the alpha channel information SEI message indicates alpha channel sample values and post-processing applied to decoded alpha planes coded in auxiliary pictures of type AUX_ALPHA and one or more associated primary pictures.

18 . The method according to claim 15 ,

wherein the coded picture is further associated in the video data with an alpha channel information SEI message which indicates the third alpha map sample and the fourth alpha map sample, and

wherein the alpha channel information SEI message having a predetermined value indicates that a simulated film grain value at a same position and color component sample is to be multiplied by interpretation sample values of a decoded auxiliary picture prior to calculating film grain values.

19 . The method according to claim 18 ,

wherein the value is an integer that is 3.

20 . The method according to claim 15 ,

wherein the film grain characteristics SEI message identifies a blending mode used to blend simulated film grain with input images.