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 time, a fix can be quickly found.

Important: After optimizing, re-optimizing, restoring, or doing any change to your images, you must flush your website's cache to see the changes. Please do it following these instructions: How to clear WordPress cache

Possible causes and solutions for poor image quality after compression

  1. Over-compression
    1. Your images are served through a third-party service that also does image compression, like JetPack's Site Accelerator. 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, go to JetPack > Settings > Performance and disable the option "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 or Lossless method instead of Lossy. If you used ShortPixel in the first place, then:
      1. Restore all the images.
      2. Select Lossless or Glossy compression method in your ShortPixel plugin settings (Settings > ShortPixel). Make sure you save the settings after you make the change.
      3. Bulk process your images (Media > Bulk ShortPixel) to optimize the images with the new compression type.
    3. Most thumbnail regeneration plugins corrupt and/or delete our logs from the WordPress database. In some cases, this could trigger a re-compression of the images. Use the reGenerate Thumbnails Advanced plugin instead, which is compatible with ShortPixel Image Optimizer plugin.
  2. Artistic pictures that need a softer image optimization method

    We recommend that you test all the optimization methods before bulk processing your images. Picture quality is subjective, and even if Lossy is the preferred method for most 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 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. That being said, the resulting thumbnails will 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 active on your WordPress site, we recommend setting the latter to Lossless/Glossy: I already used SPIO for image optimization, what settings should I use with SPAI?
  5. PNG compression is not always adequate

    The PNG image format is very good for logos, drawings, icons, and other similar graphics, but it is a suboptimal format for regular pictures, such as 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. For regular pictures, it will cause quality issues. The best approach for such images is 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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