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Container spec: clarify the background color field

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Change-Id: I03f634cbd147c2851eb06ddbc7b1014e04e21038
This commit is contained in:
Urvang Joshi 2013-03-26 17:22:18 -07:00
parent 4299f39852
commit cc635efa01
1 changed files with 12 additions and 6 deletions
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18
doc/webp-container-spec.txt
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@ -376,6 +376,7 @@ Future specifications MAY add more fields.
An animation is controlled by ANIM and ANMF chunks.
ANIM Chunk:
{:#anim_chunk}
For an animated image, this chunk contains the _global parameters_ of the
animation.
@ -392,10 +393,14 @@ animation.
Background Color: 32 bits (_uint32_)
: The background color of the canvas in \[Blue, Green, Red, Alpha\] byte order.
The background color is the color used for those pixels of the canvas that are
not covered by a frame. Background color is also used when disposal method is
`1`.
: The default background color of the canvas in \[Blue, Green, Red, Alpha\]
byte order. This color is used to fill the unused space on the canvas around the
frames, as well as the transparent pixels of the first frame. Background color
is also used when disposal method is `1`.
**Note**: Viewers that have a preferred background against which to present the
images (web browsers, for example) should ignore this value and use their
preferred background color instead.
Loop Count: 16 bits (_uint16_)
@ -463,8 +468,9 @@ the next frame on canvas:
* `0`: Do not dispose. Keep the area used by this frame as it is and render
the next frame on top of it.
* `1`: Dispose to background color (also part of this chunk). Restore the
area used by this frame to background color before rendering the next frame.
* `1`: Dispose to background color. Restore the area used by this frame to
background color before rendering the next frame. The background color is
part of the [ANIM chunk](#anim_chunk).
Frame Data: _Chunk Size_ - `16` bytes