To get the most out of viewing digital images on your computer, you should be able to see the difference (at least) between X,Y and Z and ideally A,B and C. If not, you can adjust your monitor's contrast and/or brightness setting. This alters the monitor's perceived gamma.
In digital imaging systems, color management is the controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media.

The primary goal of color management is to obtain a good match across color devices; for example, a video which should appear the same color on a computer LCD monitor, a plasma TV screen, and on a printed frame of video. Color management helps to achieve the same appearance on all of these devices, provided the devices are capable of delivering the needed color intensities. read more at wikipedia.org