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WebPImagePlugin.py decodes webp in open() #2483
Description
What did you do?
Calling Image.open() on a webp file
What did you expect to happen?
The call should be quick
What actually happened?
open() for a webp image actually decodes the webp into rgb !
So open() for a webp image is much slower than open() for a png for instance
The implementation in WebPImagePlugin.py is not efficient at all.
open should call WebPGetInfo or WebPGetFeatures but not WebPDecode !
What versions of Pillow and Python are you using?
Latest pillow (4.1) and python 2.7
Activity
hugovk commentedon Apr 11, 2017
PRs welcome.
Have a look at:
wiredfool commentedon Apr 11, 2017
There is actually a pr languishing that totally rewrites webp support.
hugovk commentedon Apr 11, 2017
christophegithubtts commentedon Apr 12, 2017
wiredfool : do you mean pr #1122 has some problems and will not be checked in ?
wiredfool commentedon Apr 12, 2017
No. I mean that there is a PR, and that it appeared to be a ground up rewrite which may or may not have the same issues as the current version of the webp plugin. IIRC, there was discussion around that PR, and then it went nowhere because it's a huge code drop that replaced existing functionality without ever discussing the differences between it and the current code.
radarhere commentedon Dec 28, 2018
#2761 being merged in on 6 Nov 2017 meant that WebPDecode is no longer called for newer versions of libwebp. Testing, if I force the legacy mode to be used, it is 424% of the time of PNG open. Testing the normal version of WebP open, I get 188% of the time of PNG open.
Is that speed up sufficient for this issue to be closed?
christophegithubtts commentedon Jan 3, 2019
That's better for sure
I guess the following line
self._decoder = _webp.WebPAnimDecoder(self.fp.read())
is responsible for 88% additional time compared to png ?
I let you close the ticket
radarhere commentedon Jan 4, 2019
No,
self._decoder = _webp.WebPAnimDecoder(self.fp.read())is only responsible for about 13% of the additional time compared to PNG.