I’ll see if I can do some tests and we can compare the quality.
My impression was that JPG compression has to discard more information on
larger sized images to lower the file size, and then you are using the
browser to resize the image resolution down. As opposed to actually
resizing the image, which in many cases may be sufficient to get the image
down to a reasonable size. My expectation is crisper images on the posts.
Happy to do the homework, if it’s something the Discourse team would
consider. Not sure what you guys are using to do the image processing, so I
don’t want to ask something that’s not included with the tool.