I get the message "serve scaled images" when using SPAI, how come?

If you installed ShortPixel Adaptive Images (SPAI) and then ran a GTMetrix test on your website and received such an error

then it is very likely that another plugin or theme is conflicting with ShortPixel thus preventing it from working correctly. Whether this is your case or not, here's how you can try to solve this:

  1. First of all, make sure there isn't a firewall or .htaccess rule preventing ShortPixel servers from accessing the original images. If so please make sure you whitelist ShortPixel's IP addresses.
  2. If the image is listed in a CSS file, ShortPixel Adaptive Images can only optimize the image; it won't be able to serve it with the right scale. To serve the scaled image via CDN you need to activate this option inside the plugin

  3. SPAI is using lazy load technology so it can deliver appropriately sized images depending on the visitor's viewport. If another plugin or theme has a similar lazy load functionality active then you need to turn it off so that SPAI's lazy load can work properly. Here's an article about known plugins that have such functionality and how to deactivate it.
  4. If none of the above helps then you can try to debug this step-by-step
    1. go to your website, click F12 and open Developer tools
    2. check whether you can see calls made to cdn.shortpixel.ai as in the screenshot below. If you can see then ShortPixel Adaptive Images works well.
    3. if you cannot see such calls to cdn.shortpixel.ai on a page with images then go to your WordPress Dashboard, select Plugins and temporary deactivate all your plugins. After that just activate ShortPixel Adaptive Images and make sure the images are served from ShortPixel CDN.
    4. Then activate, one by one, each of the other plugins and after each plugin activation, reload the test page and repeat the step b. above till you notice that the images aren't loaded from CDN anymore. When that happens it means that you found the plugin conflicting with SPAI. Congratulations! :-)
    5. Keep the conflicting plugin deactivated, activate all the other plugins that you need and make sure that SPAI is till working as explained in step b.
    6. if the conflicting plugin isn't important for your website then just keep it deactivated. If it is important then please contact us letting us know what is the conflicting plugin so we can investigate this more and possibly find a fix.

In some circumstances as for example images loaded as backgrounds (background-image property) or by JavaScript after the page is loaded, SPAI is not able to safely determine the final size of the image, as this has to be done without impacting the page performance in browser and BEFORE the image is loaded, in order to make sure only the optimal image is loaded. The site speed testers use a headless browser to do a full page render on their servers, which is not constrained by time and thus they can check the images AFTER they're loaded so some of the improvements they propose can be only done by a developer. This being said, we're continuously searching for ways to include particular cases that can be automatically handled, so if your current case is not yet rescaled, it could probably be in the future.

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