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Gamma

Adjust the gamma values of a color plane of an image


Syntax

GAMMA <cINFILE.EXT> [<cOUTFILE.EXT>] [<nRGammaValue>]
   [<nGGammaValue>] [<nBGammaValue>]


Arguments

<cINFILE.EXT>
The image file to have its gamma adjusted. 
Valid formats are GIF, PCX, or Targa.

<cOUTFILE.EXT>
The gamma corrected image file to save to.

<nRGammaValue>
The optional red gamma value to start from (default is 1.0).

<nGGammaValue>
The optional green value to start from (default is 1.0).

<nBGammaValue>
The optional blue value to start from (default is 1.0).


Remarks

Gamma values for images depend on the image's device of orgin. If an image 
is created on a device with one set of gamma values, there is a chance that 
the gamma values on a different display device will not be the same. If 
gamma values differ, an image's colors will not appear properly. Images 
scanned in from scanners will frequently need gamma value correction to 
display properly on your monitor.

Gamma accepts command line parameter passing or the use of the keyboard to 
interactively adjust the gamma values of each individual color plane or all 
color planes equally. Gamma adjustment uses floating point calculations and 
is very CPU intensive.

Use CURSOR RIGHT to raise, cursor left to lower, escape to restore color 
map. HOME, CURSOR UP, and PAGE UP will raise red, green, and blue planes. 
END, CURSOR DOWN, and PAGE DOWN will lower red, green, and blue planes. 
<cINFILE.EXT> is the image file, <cOUTFILE.EXT> is the optional filename to 
save the gamma corrected image to. <nRGammaValue> is the optional red gamma 
value to start from (default is 1.0), <nGGammaValue> is the optional green 
gamma value to start from (default is 1.0), <nBGammaValue> is the optional 
blue gamma value to start from (default is 1.0). If <nGGammaValue> and 
<nBGammaValue> are omitted, they will be set to the same values as 
<nRGammaValue>. All extensions must be one of (GIF, PCX, TGA). When the 
image is at the correct lighting, pressing enter will exit and save the 
image under <cOUTFILE.EXT>.


Example

To correct the gamma values of each color plane an equal amount to .45 
gamma value for the red, green, and blue color planes, which is the 
approximate correct value for screen display.)

GAMMA TEST.GIF OUTPUT.GIF .45

To correct the gamma value of each color plane to the value passed on the 
command line, .45 for red, .35 for green, and .55 for blue color planes. 
.45 gamma across all color planes equally is the approximate correct value 
for screen display.)

GAMMA TEST.GIF OUTPUT.GIF .45 .35 .55