Interactive Color Raster (ICR) is a protocol for displaying raster graphics on workstation screens. The protocol is implemented in NCSA Telnet for the Macintosh version 2.3. The ICR protocol shares characteristics of the Tektronix graphics terminal emulation protocol. For example, escape sequences are used to control the display.
ppmtoicr will output the appropriate sequences to create a window of the dimensions of the input pixmap, create a colormap of up to 256 colors on the display, then load the picture data into the window.
Note that there is no icrtoppm tool - this transformation is one way.
ppmtoicr ppmfile
This will create a window named
ppmfile
on the display with the correct dimensions for
ppmfile,
create and download a colormap of up
to 256 colors, and download the picture into the window. The same effect
may be achieved by the following sequence:
ppmtoicr ppmfile > filename
cat filename
To display a GIF
file using the protocol in a window titled after the input file, zoom
the displayed image by a factor of 2, and
run-length encode the data:
giftopnm giffile | ppmtoicr -w giffile -r -e 2
The protocol uses frequent fflush calls to speed up display. If the output is saved to a file for later display via cat, drawing will be much slower. In either case, increasing the Blocksize limit on the display will speed up transmission substantially.
NCSA Telnet for the Macintosh, University of Illinois at Urbana-Champaign (1989)