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webp-lossless-bitstream-spec: remove use of 'dynamics'

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when bit width or precision are meant.

Change-Id: I89c2279e99b02c3e8a3bf39860364d2ce6d909c8
This commit is contained in:
James Zern 2023-05-12 15:08:44 -07:00
parent ed27437160
commit 17e0ef1da5
1 changed files with 5 additions and 6 deletions
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11
doc/webp-lossless-bitstream-spec.txt
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@ -162,8 +162,8 @@ int image_width = ReadBits(14) + 1;
int image_height = ReadBits(14) + 1; int image_height = ReadBits(14) + 1;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 14-bit dynamics for image size limit the maximum size of a WebP lossless The 14-bit precision for image width and height limits the maximum size of a
image to 16384✕16384 pixels. WebP lossless image to 16384✕16384 pixels.
The alpha_is_used bit is a hint only, and should not impact decoding. It should The alpha_is_used bit is a hint only, and should not impact decoding. It should
be set to 0 when all alpha values are 255 in the picture, and 1 otherwise. be set to 0 when all alpha values are 255 in the picture, and 1 otherwise.
@ -428,7 +428,7 @@ performed using 8-bit two's complement (that is: uint8 range \[128..255\] is
mapped to the \[-128..-1\] range of its converted int8 value). mapped to the \[-128..-1\] range of its converted int8 value).
The multiplication is to be done using more precision (with at least 16-bit The multiplication is to be done using more precision (with at least 16-bit
dynamics). The sign extension property of the shift operation does not matter precision). The sign extension property of the shift operation does not matter
here: only the lowest 8 bits are used from the result, and there the sign here: only the lowest 8 bits are used from the result, and there the sign
extension shifting and unsigned shifting are consistent with each other. extension shifting and unsigned shifting are consistent with each other.
@ -489,9 +489,8 @@ void AddGreenToBlueAndRed(uint8 green, uint8 *red, uint8 *blue) {
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This transform is redundant as it can be modeled using the color transform, but This transform is redundant as it can be modeled using the color transform, but
it is still often useful. Since it can extend the dynamics of the color since there is no additional data here, the subtract green transform can be
transform and there is no additional data here, the subtract green transform can coded using fewer bits than a full-blown color transform.
be coded using fewer bits than a full-blown color transform.
### 4.4 Color Indexing Transform ### 4.4 Color Indexing Transform