Screen calibration: Calibrate your screen to view the images.

Save your current screen settings since the following setup might not be ideal for everyday use.
Dim the lights in the room

Set gamma correction to 1 (default on Windows and Linux but not SGI and Apple)
Set your monitor to display colors at 6500K.

You have to set Contrast to maximum or close.
In the following chart, you need to be able to read the number 2. Adjust brightness settings until you are able to read 2, add a little bit of dark until the tile around the number is barely visible. It means you can distinguish values between black and 99% grey.
Set you browser size to full screen and switch off the personal toolbar.