Zopfli compression in 6.0.0 results in a corrupted image in some cases

[bgunnink]

Using the newly-released 6.0.0 version on Windows 11 (64-bit) on the attached PNG results in the following:

> oxipng -Z -o max cover.png

Processing: cover.png
    2981x2981 pixels, PNG format
    3x8 bits/pixel, RGB
    IDAT size = 6087921 bytes
    File size = 6088031 bytes
Trying: 6 combinations
Found better combination:
    zc = 0  zs = 0  f = 4        5897004 bytes
    IDAT size = 5897004 bytes (190917 bytes decrease)
    file size = 5897114 bytes (190917 bytes = 3.14% decrease)
The resulting image is corrupted and will not be outputted.
This is a bug! Please report it at https://github.com/shssoichiro/oxipng/issues
The resulting image is corrupted

As per instructions, here I am.

The problematic image is available at https://user-images.githubusercontent.com/1986890/188520158-84a1a201-a63f-4884-b880-19980932551b.png

FWIW, I had just successfully compressed this image (same command) with oxipng 5.0.1 a few days ago.

The -o max flag doesn't make a difference, either (same error), but I don't get the error in normal mode (it can't achieve better compression and doesn't even try, I guess).

[Maingron]

Noticed the same on Windows 10. Think this only applies to high-resolution images.

[AlexTMjugador]

I'm sorry about the issue. It's caused due to the zopfli version bump to 0.7, which contains a regression that is generating corrupt streams (I can reproduce corruption problems by using the zopfli binary on the attached image). I'll try to dig further in it.

[TPS]

Is there an issue filed upstream w/ zopfli itself?

[Maingron]

For your testing, here are some more images that failed on me. Weirdly it's not applying to all image of the same source.
Failing images for testing (issue 449).zip

Edit: Note that, at least I think so, the images got compressed with an older version, so you might see a 0,00% reduction.

[AlexTMjugador]

Is there an issue filed upstream w/ zopfli itself?

No, there isn't, but that paperwork is not necessary because I'm a maintainer of that library, and I've just pushed a change that I believe will fix this issue: zopfli-rs/zopfli@fcfb76c.

I'll test the fix with OxiPNG for a bit to confirm that the attached images are working fine now.

[Maingron]

If you provide a compiled version, I can run tests too. I got the error on quite many images.

[AlexTMjugador]

Here it is a Windows build of the changes I'm testing. I've cross-compiled it from my Linux workstation and it seems to work well enough to show usage help under Wine: oxipng.zip

Edit: the problematic image attached by the issue poster has just been optimized successfully for me. Other images attached by @Maingron worked fine, too.

[Maingron]

@AlexTMjugador didn't get any errors so far. Also tried a 5760x2160 image, although I don't know if that one would have thrown an error.

[AlexTMjugador]

Thank you all for your input 😄

I've just submitted a PR that should fix the issue.