Last week I had to install the GD library on my server to enable thumbnail resizing for a premium theme. After installing the GD library on the server the image quality of newly added thumbnails for another theme got worse in terms of quality.

Thumbnails are generated in the correct sized and are not 'resized' in any way with CSS. All thumbnails are only resized keeping the aspect ratio as it is and they are not cropped.

I've already increased the image quality to 100% like this:

function volley_thumbnail_quality( $quality ) {
return 100;

add_filter( 'jpeg_quality', 'volley_thumbnail_quality' );
add_filter( 'wp_editor_set_quality', 'volley_thumbnail_quality' );

But with no visible increase in quality.

I've already found a similar question at StackOverflow but I don't want to discuss the Adobe RGB-profiles that are maybe added to the uploaded with the client yet as most editors of the website are not very tech savvy.

Is there any other way to increase the thumbnail quality?

  • Have you tried the ImageMagick module instead, as suggested in the Stack Overflow question you found? – s_ha_dum Mar 25 '14 at 14:06
  • No, I haven't done that yet – NielsPilon Mar 25 '14 at 14:09
  • 1
    I would try that. I consider it the better library. – s_ha_dum Mar 25 '14 at 14:13
  • I installed ImageMagick on the server and it looks a bit better indeed. Not as good as it was before somehow but still better. – NielsPilon Mar 25 '14 at 15:41

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