Convert a PBM Bitmap for a Matrix Orbital LCD

You will turn a monochrome PBM image into the binary image data expected by a Matrix Orbital LCD upload workflow. The installed pbmtomatrixorbital command writes that data to standard output, so the useful result is a new binary file, not another viewable PBM.

Allow about ten minutes for a first conversion. You need a Linux shell, the netpbm package, and a readable PBM file. The examples below use Netpbm 11.5.2, provided here by Debian package version 2:11.05.02-1.1build1. The command itself does not open a serial port or upload anything.

1. Check the installed command

Confirm which executable your shell will run and record the local Netpbm version:

$ command -v pbmtomatrixorbital
/usr/bin/pbmtomatrixorbital
$ pbmtomatrixorbital --version
pbmtomatrixorbital: Using libnetpbm from Netpbm Version: Netpbm 11.5.2
...

The exact build details can vary. The useful check is that the command exists and reports the expected Netpbm family. No elevated privileges are needed for this step or for a normal conversion.

2. Confirm that the input is PBM

A PBM file describes a two-colour image. Raw PBM normally begins with P4; plain PBM begins with P1. Both are valid input forms for the Netpbm reader. Inspect the file without changing it:

$ file /path/to/input.pbm
$ od -An -c -N 32 /path/to/input.pbm

Do not infer the format from the filename alone. A file called input.pbm might contain another format, and a PBM image may have a different filename. If the first bytes are not a PBM magic number, convert or export the source image to PBM with a suitable image tool first.

The PBM raster uses one bit per pixel, with black represented by a set bit. The image dimensions are part of the PBM header. This matters because the converter has no command-specific width or height option that can repair a header describing the wrong image.

3. Convert to a new output file

Pass the input pathname as the optional argument and redirect standard output to a new destination:

$ pbmtomatrixorbital /path/to/input.pbm > matrix-orbital-image.bin
$ printf 'exit=%s\n' "$?"
exit=0

A successful run normally prints no progress message because standard output is the converted image. The input is read, not modified. Keep the output name distinct from the input name: redirecting a command's output over its input can truncate the source before the converter has read it.

Shell redirection also truncates an existing destination before the command starts. Before using a real output name, check it:

$ test ! -e matrix-orbital-image.bin && echo 'destination is unused'
destination is unused

If the destination already exists and is valuable, choose a new name or make a deliberate backup first. Do not use sudo to bypass a careless pathname choice. If you accidentally create an incomplete output, remove only that output after checking the path; the original PBM should remain untouched.

4. Try a small, reproducible PBM

When diagnosing a real file, isolate the command from the image archive by feeding it a tiny plain PBM on standard input. This 8 by 4 test pattern is safe to reproduce:

$ printf 'P1\n# 8x4 test pattern\n8 4\n00000000\n00111100\n01000010\n01111110\n' \
    | pbmtomatrixorbital > /tmp/matrix-orbital-test.bin
$ wc -c /tmp/matrix-orbital-test.bin
10 /tmp/matrix-orbital-test.bin
$ xxd -g1 /tmp/matrix-orbital-test.bin
00000000: 08 04 00 0c 0a 0a 0a 0a 0c 00                    ..........

This demonstrates two details that are easy to miss. With no pathname, the program reads standard input, and its output is binary data. For this exact 8 by 4 input on Netpbm 11.5.2, the output is ten bytes: the dimensions followed by the converted raster bytes. The byte sequence is a protocol-oriented result, not a portable image file for file or an image viewer.

5. Keep upload separate from conversion

The manual mentions mo-upload.pl as a program that can send the resulting image through the serial port. That is a separate operation and is not part of pbmtomatrixorbital. First inspect and retain the generated file; only then follow the Matrix Orbital device and uploader documentation for the exact port, baud rate, display model and upload procedure.

Do not run an uploader against a live display merely to test conversion. A serial upload can change the device state, and the converter cannot verify the wiring, protocol settings or target display. If an upload fails, the binary file is still useful for retrying after checking the serial configuration. No system service needs to be stopped for the conversion itself.

6. Diagnose the likely failures

• "command not found": verify the package installation and PATH. Run command -v pbmtomatrixorbital again after correcting it.
• Input open failure: check ls -l /path/to/input.pbm, the pathname, and read permission. Changing permissions or using sudo should be a considered access decision, not the first response.
• Unexpected output size or appearance: inspect the PBM magic number and dimensions. A successful exit status means the reader and writer completed; it does not prove that the source image is the pattern you intended.
• Help behaves unexpectedly: this command has no options defined specifically for it. It recognises common libnetpbm options, but on this installation --help tells you to use man pbmtomatrixorbital and returns status 1. Use the manual rather than guessing a resize, device or serial option.

If you need to undo this guide's file operation, delete only the newly generated binary after verifying its pathname. The command does not alter the PBM input or the LCD; a separate uploader may alter the display and needs its own recovery procedure.