We have recently implemented a new system which automatically optimizes images uploaded to a Wix site. When optimizing images, Wix takes both site loading time, and image quality, into consideration.
Provided that your images are under 15mb in size, there is no need to compress or resize them before uploading them to your Wix site.
Tip: If you uploaded an image in the past and wish to improve its quality, please delete it from your site and upload the original file again, without any additional compression.
There are a few steps that you can take which will help you prepare your images for upload.
In addition, to learn about the recommended file formats, click here.