Picture quality issues when using ShortPixel

If you're unhappy with how the images look on your website after you optimized them with ShortPixel, don't despair! Most of the times, a fix can be quickly found!

Important note: after optimizing, re-optimizing, restoring, or doing any change to your images, you should flush your website's cache to see the changes. Please do it in this order:

  1. Cache plugins (WP Rocket, LiteSpeed Cache, Autoptimize SG Optimizer...)
  2. Server cache (SiteGround, Kinsta, Bluehost...)
  3. CDN cache (Cloudflare, StackPath...). Please do it from your CDN's dashboard, not through your cache plugin or hosting dashboard.
  4. Browser cache (Chrome, Firefox, Edge, Safari...)

Possible causes and solutions for poor image quality after compression

  1. Over-compression
    1. Your images are served through a third party service which also does image compression, like JetPack's Site Accelerator (see below for further specific information). These services do their own compression on the already compressed images and this can turn out to be too aggressive.
      1. To disable JetPack's Site Accelerator (formerly Photon), go to JetPack > Settings > Performance and disable "Enable site accelerator".
    2. If your images were previously compressed - either locally or with a different image optimization plugin - then we recommend you use the Glossy method instead of Lossy. If you used ShortPixel in the first place then:
      1. restore all the images.
      2. select Lossless or Glossy as image optimization algorithm. Make sure you save the settings after you make the change.
      3. run again "Bulk ShortPixel" and optimize the images.
    3. Most thumbnail regeneration plugins plugins corrupt/delete our logs from the WordPress metadata. In some cases, this could trigger the re-optimization of the images. Please, use the Regenerate Thumbnails Advanced plugin. It is compatible with the ShortPixel Image Optimizer plugin.
  2. Artistic pictures that need a softer image optimization method

    We recommend that you test all the optimization methods from our plugin before bulk processing your images. Picture quality is subjective, and even if Lossy is the preferred method for most of the cases, we set the Glossy compression algorithms for situations when quality is paramount. 
  3. Images served via mobile networks

    If you notice that your images look better on desktop than on the mobile devices, then it is possible that your ISP severely optimizes the resources for faster delivery. Some mobile providers use a transparent proxy to help reduce the traffic and they indiscriminately compress all the thumbnails. The resulting thumbnails will thus look bad but only while viewed on a mobile connection
  4. Using SPIO and SPAI simultaneously (or our image CDN from Autoptimize)

    If you have both ShortPixel Image Optimizer and ShortPixel Adaptive Images activated on your WordPress site, then our suggestion is to set the latter to Lossless/Glossy: I already used SPIO for image optimization, what settings should I use with SPAI?
  5. PNG compression not always adequate

    The PNG image format is very good for logos and schemes but it is sub-optimal when it comes to regular pictures, like a picture with people in it. PNG optimization (both Lossy and Glossy) tries, among other things, to reduce the number of colors while maintaining the visual aspect, and this, on regular pictures, will cause quality issues. The best approach for such images is to use the plugin's option to convert PNGs to JPEGs and this should result in good looking JPEG files that are much smaller than the original PNG files.

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