In PrestaShop, you can regenerate thumbnails by following these steps:
Log in to the back office of your PrestaShop store.
Navigate to the “Preferences” tab, then click on “Images”
Scroll down to the “Regenerate thumbnails” section
Select the image types for which you want to regenerate the thumbnails by checking the corresponding checkboxes.
Click on the “Regenerate thumbnails” button.
A message will appear to confirm that the regeneration process has started. You can monitor the progress of the process by checking the “Regeneration” section.
Regenerating thumbnails can be a time-consuming process, depending on the number of images you have in your store.
If you have a lot of images, you may want to consider running the process overnight or during a period of low traffic.
Keep in mind that regenerating thumbnails will overwrite the existing thumbnails, so make sure to back up your images before proceeding.
If you have a large number of images, it may be better to use a module that can help you to optimize images and regenerate thumbnails.
Regenerating thumbnails is important because it creates smaller versions of your images, which reduces the loading time of your pages, improves the overall performance of your store, and enhances the user experience. Additionally, it can be useful if you have changed the dimensions of your images or if you have noticed that some of your images are not showing correctly.