ppmtoicr – convert a portable pixmap into NCSA ICR format
ppmtoicr [-windowname name] [-expand expand] [-display display] [-rle] [ppmfile]
Reads a portable pixmap file as input. Produces an NCSA Telnet Inter‐
active Color Raster graphic file as output. If ppmfile is not sup‐
plied, ppmtoicr will read from standard input.
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 charac‐
teristics 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 col‐
ors on the display, then load the picture data into the window.
Note that there is no icrtoppm tool – this transformation is one way.
Output will be displayed in name (Default is to use ppm‐
file or “untitled” if standard input is read.)
-expandexpand Output will be expanded on display by factor expand (For
example, a value of 2 will cause four pixels to be dis‐
played for every input pixel.)
Output will be displayed on screen numbered display
-rle Use run-length encoded format for display. (This will
nearly always result in a quicker display, but may skew
To display a ppm file using the protocol:
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
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 dis‐
play will speed up transmission substantially.
NCSA Telnet for the Macintosh, University of Illinois at Urbana-Cham‐
Copyright (C) 1990 by Kanthan Pillay (svpillay@Princeton.EDU), Prince‐
ton University Computing and Information Technology.
30 July 1990 ppmtoicr