Note that there are two greyscales, running in opposite directions. Mid grey is where the upper and lower squares are identical tone. With this greyscale, the monitor can be calibrated by using the brightness and contrast controls, so that you can see every one of the squares from black through to white. The black and white squares at the ends of the scale should just BARELY be definable.
The color temp of your monitor should be set to 6500K.
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