wp_get_attachment_image_src and Photon

The problem is most likely caused by your theme’s use of wp_get_attachment_image_src. You can read more about it here:
https://www.ads-software.com/support/topic/wp_get_attachment_image_src-full-image-issues?replies=5#post-3950332

You’ll consequently need to use the method described in the second thread you linked to to stop using Photon for this particular image, thanks to the jetpack_photon_image_downsize_array filter.

If you’re not sure how to make that change in your theme, I explain things with a few more details in this thread:
https://www.ads-software.com/support/topic/photon-destroyed-slides-featured-images?replies=10#post-5092114

I hope this helps.

Before adding the image I want to check if the image is wider than 600px. Just checking, this is not possible in combination with Photon, right?

You could use the_post_thumbnail() and define a specific size there to have something that only displayed Featured Images of the correct size, and that is compatible with Photon:
https://codex.www.ads-software.com/Function_Reference/the_post_thumbnail

Here is a great thumbnail to help you create custom Featured Image sizes:
https://markjaquith.wordpress.com/2009/12/23/new-in-wordpress-2-9-post-thumbnail-images/

I don’t think that is going to work either, because what image to show depends on the image width. If there is an image with width 600+px show it, otherwise show the smaller image.

But I like the idea of simply use the_post_thumbnail and create a category for either small or big images and use conditional tags. Might be the easiest workaround. But it’s a shame I have to do it like this while there is wp_get_attachment_image_src…

You could use get_the_post_thumbnail() to check for each size you’re interested in. If get_the_post_thumbnail() returns an empty string for a particular size, then use get_the_post_thumbnail() again, but for a small size.

Yes, that is a much better solution. I might use Photon after all ??

Thanks, Jeremy, for helping me out.