Adjusting Your Monitor for Grayscale
The image above shows 17 grayscale steps from black (value of 0) to white (value of 255) with a step value of 16. Your monitor should clearly show a difference in brightness between each step. If this is not the case you should adjust the brightness and contrast of your monitor until it does. After brightness and contrast adjustment you should perform the appropriate color adjustments per your monitor manual. Proper adjustment of your monitor will allow you to see images on the web the way they were intended to be seen.
This page courtesy of and copyright Chuck Vaughn