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2753536587 / libyuv

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argb channel isolator #59

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
For some operations it would be useful to isolate 1 channel.
e.g. copy alpha from ARGB to an 8 bit image.

3 ways to do this
1. shuffle/stride
2. mask/shift
3. madd.

all 3 are already implemented and could be adapted to a new public function.

1. shuffle - similar to bayer.  read 16 bytes, pshufb, write 4.  unroll for 
more.

2. scale4 point sampler does this. shift/pack/pack.

3. The last one would isolate the channel by multiplying by 1's and 0's.  But 
an existing function already does this - ARGBToY.  So allowing this to take the 
vector as a parameter might be a flexible function.

Original issue reported on code.google.com by fbarch...@google.com on 26 Jul 2012 at 8:33

GoogleCodeExporter commented 9 years ago 
This is not immediately needed, so marking as wont fix.

Original comment by fbarch...@google.com on 16 Aug 2012 at 8:47

GoogleCodeExporter commented 9 years ago 
Deferred indefinitely.  If anyone needs this, reopen.

Original comment by fbarch...@chromium.org on 13 Sep 2012 at 12:00