I’ve noticed a strange phenomenon today. I have an html page of the theme located on my computer side by side with the web page of the theme on Magento. The very same images (they were copied to the web folder, never touched in an image program inbetween) are losing quality on Magento as opposed to the way they look on the simple html page.
Any knowledge of this happening or what setting in Magento is doing this? I assume it’s something set up to increase performance.
The product images go through some processing by Magento to make sure they have correct sizes. This could possibly result in some compression as well. The images for your page design, in the skin folder, are not processed in any way and should not lose quality.
Magento does automatically compress jpegs, but you can tell it how much to compress said images. The default is 75%, which is way too low for some things and about right for others.