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Fast filters#2679

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wiredfool merged 21 commits intopython-pillow:masterfrom
uploadcare:fast-filters
Sep 10, 2017
Merged

Fast filters#2679
wiredfool merged 21 commits intopython-pillow:masterfrom
uploadcare:fast-filters

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@homm homm commented Aug 12, 2017 •
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               Ubuntu 14.04    i2f or 16.04       Optimized
Smooth        12.47 Mpx/s     28.81 Mpx/s       44.71 Mpx/s
Sharpen       12.34 Mpx/s     29.94 Mpx/s       44.74 Mpx/s
Smooth More    4.41 Mpx/s     12.49 Mpx/s       17.61 Mpx/s

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homm commented Aug 12, 2017
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PIL/Image.py Outdated
"instance or class")

if self.im.bands == 1:
multiband = getattr(filter, 'is_multiband', False)
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@homm homm Aug 12, 2017

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All filters used to work only with single-channel images. As this is public API and there are can be custom filters in a wild, we can't just send multi-channel images to all filters. So is_multiband flag indicates that the filter is ready for multi-channel images.

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@homm homm Aug 28, 2017

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@wiredfool As of naming things is one of the hard problems in programming, I need your help there )

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I think that's a reasonable name, at least, I haven't thought of anything better.

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@homm homm Sep 7, 2017

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The another option is subclass MultibandFilter.

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That's probably cleaner, especially with an eye towards the typing PR.

_imaging.c
}

for (i = 0; i < kernelsize; ++i) {
kerneldata[i] /= divisor;
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Precompute by dividing coefficients to divisor rather than each result pixel.

@homm homm added this to the 4.3.0 milestone Aug 12, 2017
@homm homm mentioned this pull request Aug 12, 2017
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homm commented Aug 13, 2017

Oh my god! I clash with the same bug in Intel x64 CPUs with int to float conversion, as I did when was working on resampling for Pillow 2.7.

In essence: GCC version < 4.9 (at least Ubuntu 14.04, Debian 7 Wheezy, Red Hat Linux 7) generates code which runs about 2.5 times slower than GCC >= 4.9. This can be fixed using ugly hack with assembler. We decided to include this hack in Pillow 2.7 (released Jan 1, 2015). After rewriting the resampling using fixed point arithmetics, this hack become obsolete and was removed in Pillow 3.3 (Jul 1, 2016). Unlike for resampling, I don't see a way to implement kernel filters on FPA. So, I suggest to include this hack again.

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homm commented Aug 13, 2017 •
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I've just tried SSE4 for multiband images, with no specific optimizations some optimizations.

                Simple SSE4     Optimized SSE4    OpenCV
Smooth         137.25 Mpx/s    192.01 Mpx/s      163.68 Mpx/s
Sharpen        133.55 Mpx/s    171.32 Mpx/s      163.81 Mpx/s
Smooth More     45.71 Mpx/s     69.34 Mpx/s       64.01 Mpx/s

@homm homm removed the Needs Tests label Aug 15, 2017
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homm commented Sep 10, 2017

@wiredfool implemented through MultibandFilter

@wiredfool wiredfool merged commit 3b5c2c3 into python-pillow:master Sep 10, 2017
@homm homm deleted the fast-filters branch September 11, 2017 00:07
@hugovk hugovk mentioned this pull request Jan 12, 2018
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@homm homm mentioned this pull request May 21, 2018
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