HP qms 1660e Manuale Utente

Gamma

Correction,

Halftones, and

Screens

5-7

Additional Technical Information

Gamma Correction Concept

Often in scanned images, gray scaling may be too light or dark to 
show details clearly. Using gamma correction on a gray-scale image 
is similar to using a graphic equalizer on a home stereo; the range of 
gray levels is adjusted for the best possible image. This sharpens 
overall midrange contrast while blacks (shadows) and whites (high-
lights) keep their original values. Gamma correction sets grayscale 
values specified through the PostScript setgray operator to your 
printer’s gray-scale values. 

Gamma correction is linked to print resolution. The main benefit of 
gamma correction is that it improves the print quality of a scanned 
image by improving halftoning at a given resolution. To get the best 
gray-scale PostScript image at any resolution, gamma correction 
should be turned on.

You can set gamma correction through PS Executive or through the 
Administration/Emulations/PostScript/Gamma Correction menu

Administration/Emulations/PostScript/Gamma Correction

No—Don’t use gamma correction

Yes—Use gamma correction

No

Gamma correction is automatically adjusted when printer 
resolution is changed.

Gamma correction applies only to PostScript images.

Gamma correction has no affect when the printer is set to 
1200x1200 dpi resolution.

If turning on gamma correction doesn’t yield a suitable gray-
scale image for your needs, set a specific gamma correction 
value through your drawing application or through the 
PostScript settransfer operator. (See your drawing application 
documentation and the 

PostScript Language Reference 

Manual for more information.)