|PNG seems to be the image format closest to Color Cross-Browser Compatibility, in updated browsers.|
When we put a color image as a JPEG (JPG) or GIF on a webpage and publish it, so anyone on the internet can view it, different browsers will show the color and brightness differently! Color is not standardized cross-browser. The amounts of red, green and blue will show somewhat differently, as will the gamma (lightness or darkness).
If we use the PNG format, this contains some additional color-translation info not included in the JPEG and GIF formats. Therefore, a PNG is apt to be seen more nearly alike in color and brightness from browser to different browser. So the PNG format is the best thing we have right now as far as color cross-browser compatibility is concerned. That is, in the most recent versions of browsers, especially MSN's Internet Explorer.
But we must realize that browser versions developed before the year 2000 do not suport the PNG file format very well, if at all. In fact, not until Microsoft's Internet Explorer version 7.0 (Oct, 2006) was the PNG format fully supported on that platform! Most other browser types supported PNG before IE, though.
See http://www.libpng.org/pub/png/pngstatus.html - "Browser Support" for further info. But this page is mostly for older browsers.
If you're trying to sell something like photographs or other art work, you'll want as many viewers as possible to be able to see your images correctly. But only you can decide whether it's best to use the JPG or the PNG format for all your webpage images
If you're using a pc with Windows and a high level of security, you may get a warning pop-up when you click on the url of any webpage that contains PNGs, even when you might be returning to that page via the "back" feature.
One thing to remember, though, if you are plugging your computer into a TV, is that all TV sets will not be adjusted the same for color balance or brightness. The PNG format may look quite a bit different on TV sets from how it looks on computer screens that are properly color calibrated.