Update WebP encoder (cwebp) to support Alpha.

Updated cwebp (Webp Encoder) binary to support Alpha encoding.
Modified man page and WebP container spec appropriately.

Change-Id: I52f6a5cb3e870c386591e9a7776293fa6a8fb04b
This commit is contained in:
Vikas Arora
2011-12-01 15:11:34 +05:30
parent 667b769aee
commit a0ec9aace9
3 changed files with 27 additions and 28 deletions

View File

@ -32,10 +32,15 @@ A summary of all the possible options.
Print the version number (as major.minor.revision) and exit.
.TP
.B \-q float
Specify the compression factor between 0 and 100. A small factor
produces a smaller file with lower quality. Best quality is achieved
Specify the compression factor for RGB channels between 0 and 100. A small
factor produces a smaller file with lower quality. Best quality is achieved
using a value of 100. The default is 75.
.TP
.B \-alpha_q int
Specify the compression factor for alpha compression between 0 and 100.
Lossless compression of alpha is achieved using a value of 100, while the lower
values result in a lossy compression. The default is 100.
.TP
.B \-f int
Specify the strength of the deblocking filter, between 0 (no filtering)
and 100 (maximum filtering). A value of 0 will turn off any filtering.
@ -137,6 +142,14 @@ range from 1 to 6. This is only meant to help debugging.
Specify a pre-processing filter. This option is a placeholder
and has currently no effect.
.TP
.B \-alpha_method int
Specify the algorithm used for alpha compression: 0 or 1. Algorithm 0 denotes
no compression, 1 uses uses backward reference counts encoded with arithmetic
encoder. The default is 1.
.TP
.B \-noalpha
Using this option will discard the alpha channel.
.TP
.B \-noasm
Disable all assembly optimizations.
.TP