I noticed recently that some web images look pixelated and gradients look dithered. PNG images seem to have "JPEG artifacts." I never had this problem before and I don't remember making any big changes on my laptop. These are what I've done so far:
- Disabled and then uninstalled browser extensions
- Updated Flash
- System Restore (up to 2 months back)
- Reinstalled all browsers
- Turned off my antivirus/antispyware
To isolate the problem, I asked a friend to visit a website that I was having this problem with on his desktop. Here's my screenshot vs. his (both in the latest version of Chrome):


When I view local images on either Chrome, FF or Safari though, they appear fine. When I save the problem images locally, they retain their distorted quality.
At first, I thought it might be a graphics card issue but graphics in games seem to be fine (I checked WoW, League of Legends, Heroes of Newerth, Bad Company2, MW2). I first noticed this when I posted some screenshots to an SU question last Aug 12.
What could be wrong? What else can I do to fix this?