Problem Resizing / Compressing Images

Hi, WordPress has a serious problem resizing and compressing an image where a pure white background image will end up with some grey stripes in it which makes product images look really bad. I opened a support ticket detailing this which can be found here

I want to take care of the resizing and compression on my side and then just FTP upload the thumbnails, can i just rename the images correctly and WooCommerce will pick them up? Example:

I have set the “Main Image With” to 510 and the “Thumbnail Width” to 247 with the “Thumbnail Cropping” of 1:1. I then FTP Upload three images named “Example.jpg”, “Example-510×510.jpg” and “Example-247×247.jpg”. I then head up to the admin panel and set up the main product image to “Example.jpg”.

Will Woo use my thumbs? Thanks