I'm designing a website, so I care about this. The problem is the display of a critical background on the site which is based on a smoothly dithered JPG image. I have 4 test cases for this particular dithered jpg image: 1) Win 7 64-bit Firefox (v5.0 - most recent) 2) Win 7 64-bit IE (v9) 3) XP SP3 32-bit laptop Firefox (v5.0 - most recent) 4) XP SP3 32-bit laptop IE (v8) Only case (3) has an issue. The dithered JPG image runs from #336633 (top) to #669933 (bottom) - a dithered range of greens. When opened directly from the laptop in the browser (file/open), it displays differently only in case (3). In all other cases, color-pixel tools (e.g., Instant Eyedropper) identify the top and bottom colors correctly as #336633 and #669933. For case (3), the colors are identified as #227B37 and #52B833. There is another area of the same website page that uses the image which is set via CSS to #669933, and it displays properly. When this JPG is opened directly in various other image viewing tools on the laptop, it is correct. Only case (3) is different. This is so bad I will have to drastically change the website design. Before I do so, can you advise me in any way about what is going wrong?