Adjusting contrast and brightness settings, my 2 cents
The black level control was historically - and misleadingly - labeled Brightness. The brightness control is misleading because you are not changing the apparent brightness of the screen. By adjusting the brightness (black level) you are changing the contrast ratio of your screen or the apparent blackness of the screen. Many manufactures set the brightness so high you see a gray background in the frame around the video image.
Contrast ratio is the ratio of light intensity between the brightest white that can be produced and the darkest black that can be produced. For Example: When you read a newspaper, the ratio of light intensity between the white paper and the black ink is very high. Reading gray print on white paper - or black print on gray paper - is more difficult because the contrast ratio is lower. Contrast ratio--in other words, is the amount of contrast between the light and dark areas on the display. Contrast differs from brightness as it represents the difference in the luminance levels among objects. While brightness is important for discerning a black cat on the floor of a darkened room, contrast is necessary to find a polar bear in a snowstorm. A higher ratio provides greater contrast, which makes the monitor more usable in conditions of high ambient light.
With a computer display, many factors conspire to reduce the intensity of blacks. These effects reduce the contrast ratio of the screen, and can induce eyestrain. Contrast ratio is a major determinant of perceived picture quality: if a picture has high contrast ratio, you will judge it to be sharper than a picture with lower contrast ratio. To achieve good reproduced contrast ratio and good perceived picture quality, it is important to set black level accurately. The most common problem with picture reproduction on video and computer monitors is misadjustment of black level.
Remember that the black portion of a picture on your screen can never be made darker than the shade of your monitor's screen when its power is off. Anything you can do to make the screen blacker will improve its contrast ratio, and consequently reduce eyestrain and increase readability.
Adjusting your monitor
Switch your monitor on, and display a picture that contains as much absolute black as possible. Use a black desktop background pattern, or a screen saver that displays mostly black. If you notice that the displayable central portion of the screen is distinctly lighter than the margins, you need to adjust your displays black level. This may be corrected by adjusting the display's Black Level control.
Adjust Black Level (brightness) so that the black region of the picture is as black as possible, but just on the threshold of becoming visible. Avoid setting it too high, which will reduce your contrast ratio and make black characters look gray.
The Contrast control determines the light intensity produced. Once you have set black level, adjust the contrast level to set a comfortable maximum intensity.
Resist the temptation to set your monitor too bright. White should be a pleasant white, it doesn't have to illuminate your room. Operate your monitor only at a comfortable brightness level. It is not advisable to adjust the brightness to its maximum setting for continuous operation. Excessive brightness and contrast has a number of disadvantages such as
Sensitivity to flicker increases
As the intensity increases light will tend to scatter over the face of the screen, because the phosphor dots will bloom or scatter into one another. The higher the brightness of bright areas of the picture, the more light is scattered into the dark areas. This scattered light reduces the contrast ratio.
Operation at high intensity tends to make the electron beam size larger, resulting in poor focus and sharpness of the image.
To avoid these impairments, operate your CRT at as low intensity as is comfortable. Reduce the ambient light in the room. Many offices are over lit, in order to compensate for bright office environments people tend to turn up the brightness / contrast of the monitor. Another benefit of running the monitor at lower contrast setting may increase the life of the monitor.
I hope this helps, sorry it was so long.
