Paul
Computer monitors in general do not show colours that are sufficiently accurate for photographic use, so they need to be calibrated first. A device known as a colorimeter is placed in front of the screen while the supplied software gets it to display a variety of different colours, which the colorimeter measures. The software then works out the difference between the colours which should have been shown and what was actually displayed. This allows the software to build a profile which is loaded into the graphics hardware which adjusts the colours so that they are shown correctly.
Since computer monitors change over the course of their lives, they have to be calibrated regularly at least every two to four weeks. The older CRT ones are particularly prone to change significantly over short periods, but the modern LCD/LED types are much better in that regard. I do recommend running a calibration before undertaking any work where colour accuracy is important. The monitor should always first be fully warmed up for 30 minutes to an hour to ensure the accuracy of the calibration. A similar period should also be allowed before commencing any photo editing if using a pre-existing profile.
Another factor which can affect colour accuracy of the display is the brightness setting. The factory default is often 100% which is usually far too bright and can lead to the final image being printed or projected too light. Some calibration software can adjust the brightness software automatically, while others display a series of patches ranging from absolute black through to pure white to allow the user to set the brightness manually.
It is likely that the software will provide options for easy or advanced calibration. Opting for advanced will require a number of different parameters to be set, most of which will be meaningless to many people. If you have got this far in my explanation, you are probably not an expert who understands all the terms, but the easy setting will give a perfectly good result. At the end of the process you will only be required to specify the name of the profile and the interval between reminders to recalibrate the display, after which you are done.
The quality of the monitor is also significant. Most laptop screens are cheap components that cannot display colours well enough for photographic work, even when calibrated, so it is usually better to connect to an external monitor for this purpose. Most standalone monitors will be OK, but as with anything, paying more for the right equipment provides the best results.
There are several brands of monitor calibration equipment, with those from Pantone, Color Munki, Eye One and Datacolor being the most well known. The first three are in fact owned by X-Rite, which has bought a number of companies in the past few years. Some of those which are worth looking at are:
All should do a good job, but I note from the reviews on Amazon that some people have experienced problems running the X-Rite products on Apple Macs. That's not something on which I can comment, being outside of my experience.
Finally, you will see that some systems have the facility to monitor the ambient light so that the display can be modified to take account of the viewing conditions which can affect human colour perception. This function is provided since most people will not have the facilities to set up a dedicated area illuminated only by daylight balanced lighting and the walls painted a neutral grey. My recommendation is to set the screen away from the window in a room where there are no strong colours and work only by natural light. As a further step, fit a monitor hood which will help isolate the display from the surroundings. With these precautions, it will often not be necessary to take account of what is happening with the lighting.
For what it is worth, I use a ColorMunki Photo (
http://www.amazon.co.uk/Pantone-CMUNPH-X-Rite-ColorMunki-Photo/dp/B00169N0BK/ref=sr_1_2?s=software&ie=UTF8&qid=1353950099&sr=1-2) and the club's projector is calibrated with a Datacolor Spyder 2, which has long been superseded, but nevertheless still works well.
