FLiF Batch File

[brispuss]

Trying to make a batch file to recursively pack png images to flif files.

Here is the batch script -

FOR /R %%a IN (*.png) DO (flif -e -n %%a %%a.flif)

Problem is that batch tries to run and partially succeeds in doing something but then get error message about flif stopped running.

Any ideas how to get this batch file working properly, please?

[Shelwien]

Maybe try a script like this:

FOR /R %%a IN (*.png) DO (
  echo "%%a" >>log.txt
  flif -e -n "%%a" "%%a.flif"
)

In case its a problem with some specific png file, you'd see it in the log.

[brispuss]

Thanks for the quick reply!

Seems like flif is having a problem with a specific png image for some reason. I'm looking into what is different about this png image compared to other pngs which were successfully compressed.

EDIT: I've looked at one png file that flif errors out on, and there is nothing obviously different from other png files which do compress under flif.

This file is 32 bit and highly compressed, other similar png's compress OK. But this png file seems to be mostly alpha channel, I think. Maybe this is the problem?

Problem png attached.

[brispuss]

Still no joy?

Attached is a png file similar in specification to the other png file. But this file (Immortal24) is successfully compressed using flif!

Both this file (Immortal24) and the png file which fails to be compressed (21stroundblack12) are 32 bit with RGBA color space. Apart from image size and subject, the two png's seem to be identical in specification.

So why does flif fail to compress on one file and not fail on another similar file?

I'm really wanting to use flif to compress png images as it gives very good compression.

Ideas?

[Shelwien]

1) My build of flif doesn't crash, but decodes a zero-size file:

Z:\098>flif.exe -e 21stRoundBlack12.png 1.flif
libpng warning: iCCP: known incorrect sRGB profile

Z:\098>flif.exe -d 1.flif 1.png
libpng error: known incorrect sRGB profile

2) It works after "convert.exe 21stRoundBlack12.png 1.png" (imagemagick)

Maybe post an issue? https://github.com/FLIF-hub/FLIF/issues

[brispuss]

Thanks for the tests and comment.

Thinking about posting an "issue" at the github site, but it seems that development of flif may have stopped? So it may not be worthwhile posting the issue there.

In the meantime I'm using different procedures to compress png images by using precomp first and then using paq8px. . or fast paq8 compressor.

Paq8px . . compression is very slow though. So I'm currently using fpaq8 v6 which is much faster and almost provides the same compression.

[Jyrki Alakuijala]

Thanks for the tests and comment.

Thinking about posting an "issue" at the github site, but it seems that development of flif may have stopped? So it may not be worthwhile posting the issue there.

In the meantime I'm using different procedures to compress png images by using precomp first and then using paq8px. . or fast paq8 compressor.

Paq8px . . compression is very slow though. So I'm currently using fpaq8 v6 which is much faster and almost provides the same compression.

What are your thoughts on the FLIF decoding speed?

(When I designed WebP lossless, I made quite a few density compromises to keep the pretty good decoding speed, and I'm just generally curious if the decoding speed is not an issue in your use case.)

[brispuss]

FLiF decoding speed?

I haven't really paid any attention to that.

The issue here seems to be with FLiF being unable to encode/convert some png images to flip format for whatever reason(s).

What "speed" of encoding/decoding has anything to do with this issue is unknown.

[Shelwien]

Its an indirect suggestion to use webp lossless instead of flif:
https://storage.googleapis.com/downl...indows-x64.zip
cwebp.exe -z 9 -exact 21stRoundBlack12.png -o 1
dwebp.exe -nofancy -nofilter -nodither 1 -o 2
It seems to work on your "buggy" file and even produces a smaller output file.

[brispuss]

Thanks for the details!

I was aware of webp.

Although webp may produce smaller files with respect to flif files, decompressing/decoding webp files back is apparently not lossless(?)

A test compression and decompression using the supplied (in previous post) webp options of the file 21dtRoundBlack21.png produced the results -

Original png file size 15,235 bytes
Webp compressed file size 7,116 bytes
Decompressed webp file with size at 13,515 bytes

So the decompressed file does not match the original file in size. This is NOT what is wanted.

What is wanted is a decompressed file with EXACTLY the same file size as the original file.

The png files are intended to be archived, and then restored exactly to how they were originally later on. This is to ensure that these png files are the correct size as programs using these files expect them to be. If png files are not the right size, programs may crash (especially if the png files are over sized).

[Shelwien]

> to flif files, decompressing/decoding webp files back is apparently not lossless

Both flif and webp actually encode raw picture (pixels), they're not recompression algorithms.
.bmp files decoded from .png and dwebp(cwebp(.png)) would be mostly the same.
Or pngcrush(.png) and pngcrush(dwebp(cwebp(.png))).
Although webp also discards metainfo.

And for lossless compression of .pngs I can suggest either precomp, or flif/webp+pngcrush+bsdiff.

[pklat]

from my limited tests, flif has best lossless ratio. however, its slow at decoding and not supported well.
it seems best to use it for archiving only for now.
as someone already mentioned, pity it has no 'solid' option yet for large set of pictures like archivers do. ( or dictionary option )

[Shelwien]

Well, this says that it isn't: http://qlic.altervista.org/LPCB.html

As to solid flif - there's support for multi-image files.

[pklat]

sorry, mea culpa.
so there are: rkim, StuffItDeluxe, Flic, zpaq, bmf, gralic, cmix.
but most of them are either too slow or too 'exotic' imho.
stuffit deluxe is even commercial!
flif is supported by xnview, irfanview, imagemagick.

which one would you use on linux?

[Shelwien]

> stuffit deluxe is even commercial!

Here's stuffit windows binary: http://nishi.dreamhosters.com/stuffit14_v0.rar

> which one would you use on linux?

There's wine on linux, so hard to say. But I like BMF.