To view these images on a computer monitor as their creators intended them to be seen, the monitor should be calibrated to some standard. Unfortunately, there are no set standards for monitor calibration in the personal computer world. The best that can usually be done is to adjust the brightness and contrast controls to view the full tonal range of the image. For best viewing of these images, adjust your monitor to the grayscale below per the instructions. These images are optimized for viewing at 24-bit color
Adjust the brightness and contrast of your monitor so that you can see each step separately. Pay more attention to the black steps. The darkest step should be as dark as you can make it while still being able to distinguish it from the next lighter step.