Lossy #16

kornelski · 2014-03-29T03:06:28Z

--lossy option that allows inexact match against LZW dictionary, which improves compression ratio. Lossy matching does a bit of 1-dimensional dithering.

This is a very basic implementation that does recursive search of dictionary nodes.

write_compressed_data contains some duplicated code, because the lossy search function needs to use less optimized code (ignores imageline), although this probably could be refactored a bit.

edit: fixed transparency

The results are pretty good:

3.3MB original

1.25MB lossy

kohler · 2014-04-04T17:09:02Z

I am really psyched for these contributions! It may take me another week or so to go through them in depth, but wanted to confirm I've seen them.

kohler · 2014-04-04T17:11:34Z

src/gifwrite.c

+}
+
+static inline const uint8_t gif_pixel_at_pos(Gif_Image *gfi, unsigned pos);
+


I would prefer that we reuse some of the color functions that are currently in the main code. For instance it supports gamma-corrected diffs.

Unfortunately switching to kcolor didn't improve quality.

I suspect it's because it's computing distance in linear RGB colorspace, which is less perceptually accurate than computation straight in sRGB. This is because linear color gives linear luminance, but luminance has non-linear relationship with perceived lightness

Converted to linear RGB (notice disproportionately heavy deformation in dark areas):

Kept in gamma 2.2:

kornelski · 2014-04-30T15:50:38Z

I've been using it for a while and I think the implementation is solid.

iirelu · 2014-05-25T02:07:39Z

When will this be merged? It's extremely powerful and halves the sizes of my gifs.

vvo · 2014-10-18T12:59:17Z

@kohler Can you review this again? Extremely usefull! @pornel

kornelski · 2014-10-19T19:56:59Z

I've noticed there's lossy branch in the gifsicle project, so @kohler is working on it :)

I know at least ezgif.com and compressor.io are using the lossy code in production and I haven't heard any complaints, so I presume it's pretty stable.

nunofgs · 2014-12-09T23:43:46Z

@kohler any news on this PR? :)

ryanmjacobs · 2014-12-18T01:22:51Z

@kohler merge this please, it's very useful. 😄

ggamel · 2014-12-24T23:17:55Z

👍 Looking forward to lossy gifs. Hoping it can be merged soon!

alanhamlett · 2015-02-02T08:22:08Z

Merge this please!

masom · 2015-03-09T14:38:15Z

Any progress on this issue? We are using the lossy fork but we would prefer to be using the official upstream.

kornelski · 2015-09-29T14:04:59Z

FYI I'm tweaking that branch to separate the compression function into lossy and non-lossy versions, as we've discussed over email.

vvo · 2016-02-06T23:16:13Z

Any news @pornel on getting this merged? Thanks

andreyvit · 2016-02-08T09:46:22Z

+1 for merging this. Pretty please?

kornelski · 2016-02-08T10:21:53Z

If someone wants to help, there's a merge conflict that needs to be resolved.

--lossy option that allows inexact match against LZW dictionary, which improves compression ratio. Lossy matching does a bit of 1-dimensional dithering. This is a very basic implementation that does recursive search of dictionary nodes. write_compressed_data contains some duplicated code, because the lossy search function needs to use less optimized code (ignores imageline), although this probably could be refactored a bit. The results are pretty good: * Original: 3.3MB * Lossy: 1.25MB Based on gifsicle which implements lossy LZW compression. It can reduce animgif file sizes by 30%—50% at a cost of some dithering/noise. * https://pornel.net/lossygif * https://github.com/pornel/giflossy Closed: kohler#16

--lossy option that allows inexact match against LZW dictionary, which improves compression ratio. Lossy matching does a bit of 1-dimensional dithering. This is a very basic implementation that does recursive search of dictionary nodes. write_compressed_data contains some duplicated code, because the lossy search function needs to use less optimized code (ignores imageline), although this probably could be refactored a bit. The results are pretty good: — Original: 3.3MB — Lossy: 1.25MB Based on gifsicle which implements lossy LZW compression. It can reduce animgif file sizes by 30%—50% at a cost of some dithering/noise. — https://pornel.net/lossygif — https://github.com/pornel/giflossy Closed: kohler#16

saurabheights · 2017-04-18T09:32:04Z

@pornel @kohler : Currently, any changes/fixes made in kohler/gifsicle are not pulled into lossy pornel repo. Thus, getting this PR merged would reduce such issues.

I tried looking into the merge issue but didn't properly understand. There are two PR #16(this one) and #72. Also, I see denji:lossy-kornel, pornel:lossy, kohler:lossy branches. It's quite perplexing to understand which one needs resolution. If you could inform which branch needs the fix, I would be glad to get this merged.

Also, there has been some conversation between kohler and pornel. If anything of relevance I should know, it would help.

kornelski · 2017-09-16T01:39:03Z

Having a pull request stuck in limbo for 3 years is disheartening. I'm giving up on contributing.

If anyone wants it, it's merged into my fork: https://github.com/pornel/giflossy

vvo · 2017-09-18T13:49:26Z

I am really psyched for these contributions! It may take me another week or so to go through them in depth, but wanted to confirm I've seen them.

@kohler and @pornel Thanks both for great contributions. It's very hard to play the open source game but both gifiscle and giflossy are great! Everyone wants them to merge so we can remove any specifics in readmes explaining how to install giflossy/gisicle and the differences.

I hope @kohler you can give some more help and finally make the tedious work of merging the changes. Thanks ..

seefood · 2017-11-19T15:48:20Z

Another +1 for this PR. 3 years is a ridiculous amount of time. @kohler Can you at least clue us in to the reason for the holdup?

fatso83 · 2018-01-30T16:07:47Z

Oh, well, no need to get antsy about this not getting merged. Giflossy is the new gifsicle anyway.

seefood · 2018-02-01T13:01:10Z

Sadly not when you apt install gifsicle. Yet.

gingerbeardman · 2018-03-21T13:51:10Z

Really poor form not merging this @kohler - what's up with that?

wheelerlaw · 2019-01-15T15:59:14Z

Looks like this project is dead
@kornelski Could you enable issues on your fork? Since this project is dead, it would be nice to have a place where issues could be addressed.

seefood · 2019-01-16T15:32:57Z

@wheelerlaw the fact he wrote somw code for it does not mean he wants to adopt the whole project and become the new maintainer, you know :-)

ghost · 2019-04-18T00:54:16Z

Thanks @kornelski !!

--lossy option that allows inexact match against LZW dictionary, which improves compression ratio. Lossy matching does a bit of 1-dimensional dithering. This is a very basic implementation that does recursive search of dictionary nodes. write_compressed_data contains some duplicated code, because the lossy search function needs to use less optimized code (ignores imageline), although this probably could be refactored a bit. The results are pretty good: — Original: 3.3MB — Lossy: 1.25MB Based on gifsicle which implements lossy LZW compression. It can reduce animgif file sizes by 30%—50% at a cost of some dithering/noise. — https://pornel.net/lossygif — https://github.com/pornel/giflossy Closed: #16

kohler · 2019-04-18T13:09:11Z

Thanks very much to @kornelski for the original patch.

The patch was not merged initially because it uses a completely different approach to color comparison than the rest of Gifsicle does. Kornel added his own color comparison subsystem exclusively to gifwrite.c, not using the existing subsystem.

There were other issues which I mentioned to Kornel (like the name of the option and some misspellings) which he did not change, but those issues weren't important.

In long-ago offline conversation we discussed this. Kornel has some concerns about the current color comparison subsystem, and evidence that it behaves badly esp. on dark areas of images, but there are also images on which it does much better than median-cut. I was hoping we would come to a shared, better color subsystem, but we did not.

I just merged it. As people said, it was about time.

Thank you to the commenters who said nicely that it was about time. And especially thanks to Kornel.

No thank you to the commenters who complained heatedly or acted like they deserved something. You are part of what makes open source hard.

kohler reviewed Apr 4, 2014
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ryanmjacobs mentioned this pull request Dec 18, 2014

gifsicle: unrecognized option ‘--lossy=80’ vvo/gifify#9

Closed

mainfraame mentioned this pull request Jan 14, 2015

"--lossy=80,--colors 80,..." - unrecognized vvo/gifify#13

Closed

shinnn mentioned this pull request Jul 17, 2016

giflossy imagemin/gifsicle-bin#62

Closed

denji mentioned this pull request Jul 17, 2016

Implement --lossy LZW compression #72

Closed

kornelski added 3 commits October 11, 2016 18:51

Unused const

0070caa

NULL

2f0b73c

Merge branch 'master' into lossy-kornel

688050f

saurabheights mentioned this pull request Apr 22, 2017

Resolved conflict to merge giflossy #97

Closed

kornelski force-pushed the lossy branch from 122b9cb to 688050f Compare May 26, 2017 18:19

kornelski closed this Sep 16, 2017

Kristinita mentioned this pull request Jan 30, 2019

feature_request(services): lossygif and ShortPixel support NickeManarin/ScreenToGif#445

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Lossy #16

Lossy #16

kornelski commented Mar 29, 2014

kohler commented Apr 4, 2014

kohler Apr 4, 2014

kornelski Apr 4, 2014

kornelski commented Apr 30, 2014

iirelu commented May 25, 2014

vvo commented Oct 18, 2014

kornelski commented Oct 19, 2014

nunofgs commented Dec 9, 2014

ryanmjacobs commented Dec 18, 2014

ggamel commented Dec 24, 2014

alanhamlett commented Feb 2, 2015

masom commented Mar 9, 2015

kornelski commented Sep 29, 2015

vvo commented Feb 6, 2016

andreyvit commented Feb 8, 2016

kornelski commented Feb 8, 2016

saurabheights commented Apr 18, 2017

kornelski commented Sep 16, 2017

vvo commented Sep 18, 2017

seefood commented Nov 19, 2017

fatso83 commented Jan 30, 2018

seefood commented Feb 1, 2018

gingerbeardman commented Mar 21, 2018

wheelerlaw commented Jan 15, 2019 •

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seefood commented Jan 16, 2019

ghost commented Apr 18, 2019

kohler commented Apr 18, 2019

		}

		static inline const uint8_t gif_pixel_at_pos(Gif_Image *gfi, unsigned pos);

Lossy #16

Lossy #16

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kornelski commented Mar 29, 2014

3.3MB original

1.25MB lossy

kohler commented Apr 4, 2014

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kornelski commented Apr 30, 2014

iirelu commented May 25, 2014

vvo commented Oct 18, 2014

kornelski commented Oct 19, 2014

nunofgs commented Dec 9, 2014

ryanmjacobs commented Dec 18, 2014

ggamel commented Dec 24, 2014

alanhamlett commented Feb 2, 2015

masom commented Mar 9, 2015

kornelski commented Sep 29, 2015

vvo commented Feb 6, 2016

andreyvit commented Feb 8, 2016

kornelski commented Feb 8, 2016

saurabheights commented Apr 18, 2017

kornelski commented Sep 16, 2017

vvo commented Sep 18, 2017

seefood commented Nov 19, 2017

fatso83 commented Jan 30, 2018

seefood commented Feb 1, 2018

gingerbeardman commented Mar 21, 2018

wheelerlaw commented Jan 15, 2019 • edited Loading

seefood commented Jan 16, 2019

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kohler commented Apr 18, 2019

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