

i.grey.scale - 

The GRASS imagery program that applies a histogram contrast stretch to
a \map layer\ is called i.grey.scale.  i.grey.scale is actually a
contrast enhancement that assigns a histogram contrast stretch grey
scale color table to a map layer.  The histrogram contrast stretch
expands the original range of \digital\ values in the map or image to
utilize the full range or sensitivity of the display device.  This is
done primarily to improve visual image analysis, and may be used prior
to computer-assisted clarification, change detection or other raw
spectral image analysis because it does not change the original pixel
values.  As each band file is extracted from tape using the 'i.tape'
programs, a histogram contrast stretch grey scale color table is given
to each band.

One use for i.grey.scale is to improve the visual interpretation of
features within a subset of an already extracted raster file when the
subset has low contrast.  The contrast stretch algorithm expands the
existing range of pixel values (30 to 101) to the full range (0 to
255), making the visual interpretation of the data easier.

Manual entry for \i.grey.scale\




