section b of routines in color.i

functions in color.i - b

brighten


    brighten, factor  
 or brighten  


brighten the current palette by the specified FACTOR.  
The FACTOR is the slope of the transfer function for the color value  
(see to_hsv for a description of the hsv color system); a value of  
1.0 always remains 1.0, but values near 0.0 change by FACTOR.  
FACTOR= 1.0 is a no-op.  The default factor is 4.0.  
Interpreted function, defined at i/color.i   line 38