Wrong color on book thumbnail

[MEGAMENE]

I've noticed that some of my manga appear in a different color instead of just black and white on the book page thumbnails.
Here's an example:

[gotson]

Could you provide a link to the original file?

[MEGAMENE]

Sure, here's the link:
https://files.catbox.moe/l8pwhs.cbz
It happens with a lot of files.

[gotson]

Thanks. I did a quick test and i can confirm it's not coming from the imageio conversion, but from the thumbnail library in particular.

Their github repo is apparently full of issues with png images. I'll look for another library to replace it.

[gotson]

🎉 This issue has been resolved in version 0.13.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[MEGAMENE]

The new update seems to have broken some thumbnails, both in the book view and page preview.
Here's an example:
https://files.catbox.moe/mqrlj1.cbz

[gotson]

What do you mean by "broken" ?

For the book thumbnails show in the gallery, you need to regenerate them, either via the admin endpoint (available via swagger), or by analyzing the books again (from the 3 dots menu).

For all thumbnails, you also need to clear your browser cache.

[gotson]

It seems the first image of your file as alpha channels, hence the problem.

[MEGAMENE]

What do you mean by "broken" ?

For the book thumbnails show in the gallery, you need to regenerate them, either via the admin endpoint (available via swagger), or by analyzing the books again (from the 3 dots menu).

For all thumbnails, you also need to clear your browser cache.

I analyzed all of the files after the update and some don't generate the thumbnails.

Here's an example:

[gotson]

Both libraries have issues: the original one handles transparency channels, but generates color artefacts, the new one cannot handle alpha.

I would prefer incorrect colors to nothing, so i'll switch back to the original library.

[MEGAMENE]

Both libraries have issues: the original one handles transparency channels, but generates color artefacts, the new one cannot handle alpha.

I would prefer incorrect colors to nothing, so i'll switch back to the original library.

Yeah, that's probably the best option of the two.
Maybe later there's another way to fix this problem, I don't know enough about java or images to be of any help.

[gotson]

From what i've gathered, generating good looking thumbnails is complex enough that people wrote libraries to do it :) I have no plans on writing my own code for that!

[MEGAMENE]

From what i've gathered, generating good looking thumbnails is complex enough that people wrote libraries to do it :) I have no plans on writing my own code for that!

Yeah, that makes sense.
Maybe an option would be to convert png to jpeg and then create the thumbnail?
That should remove the transparency problem, no?

[gotson]

Nothing is as simple in the world of imaging, unfortunately.