Some notes about colour profiles embedded in images. This is a separate issue from colour calibrating your monitor/computer. The software that saves your final image to jpg may be inserting colour profiles with or without your knowledge. I highly recommend against this! Photoshop can insert colour profiles, but it is often unclear whether it's inserting one or not. I do all my post-work (re-sizing, signatures) in the Mac version of Photoshop 7/CS, so I can't speak for other programs. I'm assuming a colour profile can only be inserted if you have colour-calibrated your machine, but I'm not entirely sure about that as all Macs use some colour-calibration by default. Obviously I have a PC, but I never calibrated it as it has always been consistent with my other systems, and I always do a final colour check on the Mac before publishing.

I had a big problem with this a couple of years ago. Some background information: I run a website that provides my images as computer backgrounds, thus I was trying to make my images look as good as possible on -all- computers, not just ones I control. I embedded colour profiles in all my images. The end result was total colour chaos. Some computers ignored the profile, others used it but made the images look wrong. I even had inconsistencies within the same software package, where sometimes the colour profile would be used, and sometimes not, and Internet Explorer can be set to show images like they have a colour profile when they don't even have one! I ended up re-doing hundreds of images to remove the colour profiles.

I wrote a rant after I had the issue figured out, you can read it here. There are some example images there you can use to test your computer with.

Another thing I would recommend is to know your monitor. Look at your images on other monitors/computers. Visit a friend and have a look at your Renderosity gallery from there. Visit the library. Spend a buck and go to Kinkos. If you don't want to log into Renderosity from a public computer, upload a couple of images to one of the free hosting services. If your images look significantly different on other computers than on your own, maybe you have a problem.

It's been my experience that old CRTs often start losing quality. My last 23" CRT (purchased in 1998) was a colour nightmare at the end. Laptop screens are another source of problems, I suspect because the screens may be designed to be low-power, but that causes gamma issues and often a lack of saturation. I love my 12" PowerBook, but I would never ever do colour work on it; I just can't see subtle hues, even when I know they are there. Not all laptop screens are bad, for example the 17" PowerBook has very nice colour reproduction, as do some high-end PC laptops, but it's something to watch for.