BillyS - 12:59 pm on Oct 14, 2010 (gmt 0)
But I am pretty sure you can do the same in PhotoShop.
I'm still using photoshop 7 and you can view the image in multiple window panes and see the impact of a change (from the original).
There are a lot of ways to tweak photoshop to try and get the best possible image. You can limit the color palate... look at those options.
I'm happy with photoshop, so I've never looked around. Did you look at Gimp? It's free and your only requirement is compression - which is a basic.