What is the optimum size and pixel resolution for images in blog posts in order to reduce file size to a minimum but keep them a decent on-screen quality?
I’ve also seen an export seting in PhotoShop to optimise colours for web use. Is this is worthwhile setting to use for reducing the file size of photos?
Assuming you want best quality on the post and not when clicking to view a larger version of the image, then
resolution: 72 (that’s what all browsers display);
optimum pixel width: no wider than the maximum for the main column of the theme you’re using.
In that case the filesize is small, so optimizing for the web isn’t very important.