Strange image degradation

Can you please post the original image somewhere (unaltered), and link to it here?

This is the original image

I ran it through resizing with both Imsanity and EWWW IO. They both use pretty much the same resizing code, but I wanted to see if there was any difference. They use the built-in WP_Image_Editor to scale the images, and neither produced any degradation on my site.
Do you have any image optimization plugins besides Imsanity installed?
If so, disable your IO plugin and check to see if the image degrades.
Otherwise, disable all plugins, test with just Imsanity, and see if the issue persists. If so, then I suspect a server-side issue. Otherwise, if that resolves the issue, enable plugins one at a time until the issue is found.

I don’t think that I have any other image IO plugins installed.

Do you find any?:

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• This reply was modified 8 years, 1 month ago by mpek.

none of those look like IO plugins to me, and many of them I’m familiar with.
One other thing you can check before doing the standard “disable all plugins” routine, is this:
Install EWWW IO, and just check the plugin status section on the EWWW IO settings page to see what it shows for available image libraries (GD, Imagick, or Gmagick). If they all show red, then that’s the problem. If at least one of them is green, then we can rule out missing PHP libraries.

I just deactivated all but Imsanity and the same strange degradation with that image.
I uninstalled (deactivating and deleting) Imsanity and reinstalled it from www.ads-software.com, same degradation.

Yeah, then we need to see what image libraries your site is using. EWWW is an easy way to check that, unless you want to use the phpinfo() function to create a PHP test page:
1. Create a new text file named testinfo.php with this single line of code:
<?php phpinfo(); ?>
2. Put that file in the root of your WordPress install
3. Send me the link via https://ewww.io/contact-us/

For example, if your site is at https://www.example.com/ the link to the testinfo.php file should be https://www.example.com/testinfo.php

Got it, just sent you the link. Thank you for looking into it!

Oh Wow, it’s a bug in ImageMagick from what I can see. I was just using GD, and it displayed fine. But I noted you had the imagick extension enabled, so WP will prefer that. When I enabled that on my server, and uploaded the image, I get the same degradation.
Unless you have some attachment to ImageMagick, I would just disable it and let WordPress use GD instead.

I can confirm. I had to ask Hoster to deactivate Imagick. Now, that it’s deactivated the image degradation is gone and the upload looks like it is supposed to look.