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!
Possible causes and solutions for poor image quality after compression:
- Your images are served through a third party service which also does image compression, like JetPack's Site Accelerator (formerly Photon). This service does it's own compression on the already compressed images and this can turn out to be too aggressive.
- 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:
- restore all the images
- select Lossless or Glossy as image optimization algorithm. Make sure you save the settings after you make the chance.
- run again Bulk ShortPixel and optimize the images
- Most "regenerate thumbnails" plugins corrupt/delete our logs from the WP 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 Optimization plugin.
- Site Accelerator from JetPack has an image optimization component. You can disable it or use a softer optimization method in the ShortPixel' settings.
- 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.
- 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
- Using SPIO and SPAI simultaneously (or our image CDN from Autoptimize)
If you have both, the ShortPixel Image Optimization plugin and the ShortPixel Adaptive Images activated in the WP dashboard, then our suggestion is to set the latter to Lossless/Glossy.
- 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.