Gray scale JPEG image is turned into a PNG with inverted colors after caching

[sasensi]

First, thanks a lot for this service which I'm a huge fan of an which I use regularly.

This is the third time that I notice a weird behavior with some kinds of images so I decided to report it in case there is something to fix about it. The first two times, I didn't gather the input image so I'm only able to provide one now but I know that it happened other times in the past with other images.

So here are:

• the source image https://cipmarseille.fr/images/auteurs/2043_auteur_20120511174919.jpg
• the cached image https://images.weserv.nl/?url=https://cipmarseille.fr/images/auteurs/2043_auteur_20120511174919.jpg As you can see, this happen even without using any of the available query parameters (which I use for my real use case). So there are 2 surprising things:
  • the image is a PNG while the input was a JPEG
  • the colors are inverted and the background is transparent

I don't know much about image format and neither about the processing that you apply on them by default. But I had a quick look at two input files (one which is working and this one) with exiftool. And I noticed that, among other differences, this image was referenced as a gray scale one so I wonder if this could be a clue ?

In the past, in order to workaround this, I opened and resaved the file in a software like Photoshop. I guess that this changed the meta data and somehow fix the issue.

Hoping that you can help me with this. Thanks in advance.

[andrieslouw]

@kleisauke: Care to investigate? Maybe a funky color-profile? Not sure if it's libvips or some third-party lib.

[andrieslouw]

I've been informed that it indeed is libvips, and that a fix is being worked on since your report. We'll update if there's more info.

[andrieslouw]

In the meantime, &output=jpg will mitigate the issue: https://images.weserv.nl/?url=https://cipmarseille.fr/images/auteurs/2043_auteur_20120511174919.jpg&output=jpg

[sasensi]

@andrieslouw, awesome, thank you for your updates and advices.

[kleisauke]

This has been fixed with libvips 8.14.2 (see https://github.com/libvips/libvips/discussions/3361 for details), which has just been rolled out to production. Thanks for reporting this!

[sasensi]

Thank you very much for the fix.