Some transparent PNGs are getting a black background when transcoded to webp

Hi there!

We have Cloudflare’s setting that serves images as webp where possible. In the last two weeks, there seems to have been a regression where a small fraction of these images (maybe 2% to 5%) are sometimes getting served with a black background instead of a transparent background.

As an example: https://runescape.wiki/images/8/83/Abyssal_mystic_orb.png?45a1b has a black background (at least for most POPs I’ve tried), but if we remove image/webp from the Accept header, it serves the correct image without a black background.

Is this a known issue? Is there anything we can do to help debug it and get it fixed faster?

When I look at in Safari, I see that it looks like someone erased the background of the image, so it wasn’t generated as a transparent background PNG. That might be the problem, as the conversion might not be picking out the right transparency mask.

Maybe Support can pass this info along for improvement.

Login to Cloudflare and then contact Cloudflare Support by clicking on the Get More Help button.