code review 5683050: go.image/tiff: optimize reading uncompressed files from...

go.image/tiff: optimize reading uncompressed files from a tiff.buffer.

In case the image is read via a tiff.buffer, avoid copying the
data strip before decoding it. Remove corresponding TODO.
Speeds up reading uncompressed images (which is the common case)
and uses much less memory.

benchmark                      old ns/op    new ns/op    delta
BenchmarkDecodeCompressed        4619438      4630774   +0.25%
BenchmarkDecodeUncompressed       260809       219875  -15.70%

[bsiegert, 2012-02-20 19:02:15]

Hello nigeltao@golang.org (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go.image

[nigeltao, 2012-02-21 00:24:11]

LGTM.

[nigeltao, 2012-02-21 00:25:33]

*** Submitted as a06dc69107c7 ***

go.image/tiff: optimize reading uncompressed files from a tiff.buffer.

In case the image is read via a tiff.buffer, avoid copying the
data strip before decoding it. Remove corresponding TODO.
Speeds up reading uncompressed images (which is the common case)
and uses much less memory.

benchmark                      old ns/op    new ns/op    delta
BenchmarkDecodeCompressed        4619438      4630774   +0.25%
BenchmarkDecodeUncompressed       260809       219875  -15.70%

R=nigeltao
CC=golang-dev
http://codereview.appspot.com/5683050

Committer: Nigel Tao <nigeltao@golang.org>