xv is an interactive image manipulation program for the
X Window System. It can operate on images
in the GIF, JPEG, TIFF, PBM, PGM, PPM, XPM, X11 bitmap, Sun
Rasterfile, Targa, RLE, RGB, BMP, PCX, FITS, and PM formats on
all known types of X displays. It can generate PostScript files,
and if you have ghostscript (version 2.6 or above)
installed on your machine, it can also display them.
xv lets you do a large number of things (many of them
actually useful), including, but not limited to, the following:
display an image in a window on the screen
display an image on the root window, in a variety of
styles
grab any rectangular portion of the screen and turn it
into an image
arbitrarily stretch, compress, rotate or flip the image
crop or pad images
view files as ASCII text or hexadecimal data
magnify any portion of the image by any amount, up to the
size of the screen
determine pixel values and x,y coordinates in the image
adjust image brightness and contrast with a gamma
correction function
apply different gamma functions to the Red, Green, and
Blue color components, to correct for non-linear color
response
adjust global image saturation
perform global hue remapping
perform histogram equalization
run a number of image-processing algorithms on any
rectangular portion of the image
edit an image's colormap
reduce the number of colors in an image
dither in color and b/w
crop off solid borders automatically
convert image formats
Oddly enough, I'm still having a horrible time tracking down
some minor bug in the Automatic Checkbook Balancing
Module , and once again it fails to make it into the official
xv distribution.