Color shift (lightening) when using "Save for Web & Devices..."

Question

Can someone please let me know why I'm getting a color shift (the entire image lightens noticably) when I export an image or animated gif with "Save for Web & Devices...". It happens on PCs and Macs, and with both CS3 and CS2.
I've been using this feature (flawlessly until a few months ago) long enough to realize that there are several settings to adjust the color table, dithering, web snap, etc., but adjusting these settings don't seem to fix the problem. When I use "Save As..." the color shift doesn't occur, and that's been my workaround, but I'm currently trying to save a few animated gifs, which must be saved with "Save for Web & Devices..." in order to retain the animation.
Please help!! Many thanks.

Answer 1

Ah ha! I thought so. The only reason I can speak on this topic at all is because of what I was forced to learn when I started using a Dell LCD flatscreen.
As mentioned earlier, most monitors are pretty close to sRGB, which made web work somewhat easier. However, it seems recently some so-called "wide gamut" monitors have come to market, including the recent crop of Dells. The new Dells can produce a gamut that is closer to Adobe RGB than sRGB. This means -- speaking loosely -- it can produce brighter and more saturated colours than an "sRGB" type monitor.
RGB numbers, in the context of a defined colour space, represent an "actual" real life colour. A very bright red in sRGB colour space may be represented by r255b0g0, but that same "actual" red colour is represented in the wider Adobe RGB colour space by r219b0g0. Adobe RGB, being wider than sRGB, can include still brighter reds than sRGB's brightest red, hence where sRGB hits a roof at r255, Adobe RGB can keep going higher.
Imagine two ladders, each with ten steps on it. The Adobe RGB ladder is taller than the sRGB ladder, even though they both have ten steps. The 9th step is higher (i.e. brighter) on the Adobe RGB ladder than on the sRGB ladder. So if an image contains the RGB values of r219b0g0, well if you assign it to sRGB, it will not be a very bright red. If you assign it to Adobe RGB, it will be a brighter red, because that "ladder step" (like the 9th step) is higher than the same step in sRGB.
This is why your image appears brighter when viewed in SFW and in web browsers. Photoshop knows it's supposed to be using sRGB colour space, but SFW and web browsers DOESN'T, and so it just assigns your monitor colour space, which with these Dell monitors is wider than sRGB.
I think the Dell monitor is fine...I still highly recommend purchasing some type of hardware calibration utitily (one that has a thingy that attaches to the screen to measure the light being emitted). Properly calibrate and profile your monitor, trust what you see in Photoshop, convert to sRGB for web images, and forget the rest. Either way, your images will look "good" on some people's monitors and "bad" on others.