The gray map is used mainly to adjust the brightness and contrast of the bit map approximations to the pix map. It is also used when printing pix maps on PostScript devices and when saving certain types of files.
Clicking on the brightness and contrast controls will change the gray map to the values you set.
~C~~P4641~
~L~
If you option-click on the brightness control the brightness indicator will be reset to its center position. The same can be done to the contrast control.
The controls are not the only way to adjust the gray map. By clicking and dragging in the map area itself you have total freedom over the gray mapping. By option-clicking at separate points you will be able to draw straight lines on the gray map.
~C~~P19177~
~L~
The above illustration shows how the input values are normally mapped to the output values. As an example let us invert the image by mapping the white input values to black and the black input values to white.
