THE UTAH RASTER TOOLKIT
Version 3.1c - Dec 5, 2012
The Utah Raster toolkit is a collection of programs and C routines for
dealing with raster images commonly encountered in computer graphics. It
provides the following major functions:
* A device and system independent image format for storing images
and information about them. Called the RLE format, it uses
run length encoding to reduce storage space for most images.
* A library of C routines for reading, writing and manipulating
images stored in the RLE format.
* A collections of programs for manipulating and displaying RLE
The device independent RLE file has two parts, the header, which stores
information about the image (size, position, channel information,
color maps, comments, etc), and the actual image data in a run length
encoded format. The RLE format often requires about a third of the
available space for most "image synthesis" style images. If the image
does not compress well, the RLE format stores it as straight pixel data
with little extra overhead. The format was first developed around
1983 at the University of Utah.
C routines are provided for setting up and reading the image header,
and for reading and writing the image a scanline at a time. Images can
be read or written using two different methods. Using the "row" method,
the library performs the RLE encoding and decoding. With the "raw" method,
scanlines are constructed directly with RLE opcodes. Additional routines
are available for generating dither matrices (e.g., for display programs
running on devices with less than 24 bits of color).
applymap - Apply color map values to pixel values.
avg4 - Downfilter an image by 1/4, generating a matte channel if one
didn't previously exist
crop - Crop an image.
dvirle - Convert TeX output into anti-aliased images.
fant - Rotate and/or scale in image by an arbitrary (float) value.
mcut - Quantize an image from 24 to eight bits using the median cut
mergechan - Merge several channels from different files into a single
pyrmask - Blend images using Gaussian pyramids.
repos - Change the position in the RLE header.
rleClock - Generate an image of a clock.
rleaddcom - Add a comment to the RLE file's header.
rlebg - Generate a solid or variable background.
rlebox - Find the actual non-background area of an image.
rlecomp - Digital image compositor. Provides the operations over, atop,
in, out, xor, plus, minus and diff on two images.
rledither - Floyd-Steinberg to a given color map.
rleflip - Rotate an image by 90/180 degree increments.
rlehdr - Dump the contents of the RLE header in human readable form.
rlehisto - Generate the histogram of an RLE file.
rleldmap - Load a color map into an RLE file from a variety of sources.
rlemandl - Generate Mandlebrot sets as RLE files.
rlenoise - Adds random noise to an image.
rlepatch - Overlay several smaller images over a larger one.
rleprint - Print all pixel values.
rlequant - Variance-based color quantization.
rlescale - Generates gray scale and color scale RLE files.
rleselect - Select specific images from a file.
rlesetbg - Set the background color stored in the RLE header.
rleskel - A skeleton application, for rolling your own.
rlespiff - Simple contrast enhancement to "spiff up" images.
rlesplice - Splice images together horizontally or vertically.
rlesplit - Split a file containing several images into several files.
rleswap - Swap, copy or delete channels in an RLE file.
rlezoom - Enlarge or shrink an image with pixel replication.
smush - Perform a simple Gaussian filter on an image.
to8 - Convert a 24 bit RGB image to an eight bit dithered one.
tobw - Convert 24 bits to 8 bits black and white.
unexp - Convert an "exponential" image to a displayable one.
unslice - Quickly assemble an image from several horizontal strips
Format conversion programs are provided for:
- Ascii (line printer pictures) (to)
- Cubicomp image format (from)
- GIF (to and from)
- MacPaint (to and from)
- PBMPLUS pgm (from) and ppm (to and from)
- PostScript (to)
- Sun rasterfiles (to and from)
- Targa image format (from)
- TIFF (to and from)
- Wasatch paint systems (from)
- Wavefront 'RLA' format (to and from)
- Simple pixel streams (color & B&W) (to and from)
The display programs included with the original URT distributions have been
removed. If converting to other formats proves insufficient for debugging
purposes, a cross-platform viewer based on a toolkit like FLTK would be more
appropriate to modern hardware than the original special purpose get tools.