HP 815MFP - Manual (Page 104)

98 hp designjet 815mfp & scanner 4200
gray balance
Gray Balance configuration offers the adjustment of gamma values
for red, green, and blue. The purpose is to ensure a 100% neutral
appearance of printed gray. To assist you in setting the Gray
Balance values for your printer, you can print out a set of gray
scales with varying combinations of gamma by pressing the Print
Gray Balance Sheet button. With the resulting printout you can
visually determine the most neutral scale, read the gamma values off
the printout and enter these values in the Gray Balance settings. The
Gray Balance Sheet is shown below:
The Gray Balance Sheet displays a matrix with the red setting on
the bottom axis and the green setting on the left. A single element in
the matrix is a row of shades, as they look at the given gamma
values. The blue value is fixed to 1.0.
You select the best row of shades in the matrix and use the gamma
values to make your settings in the dialog. Start out in the middle of
the sheet (1.0, 1.0, 1.0), and step up/down or left/right. If you
believe the best values lie between two patches, you are free to
enter mid values like 1.1 instead of 1.0 or 1.2. In the example
above, if the row that shows the best balance is the one encircled
then you would set Gray Balance to red = 0.6, green = 0.8 and
blue = 1.0 in the dialog.
If no satisfactory standard Gray Balance can be found, Advanced
Gray Balance calibration is necessary.