Convert Microdesign MDA Files to PBM with mdatopbm

mdatopbm turns a Microdesign .mda or .mdp file into a PBM bitmap in one command. This guide covers the conversion plus the checks that prove the output is a real image at the size you expect, and takes about ten minutes if the input file is already on disk. The examples use Netpbm 11.5.2, installed here as Debian package netpbm 2:11.05.02-1.1build1.

You need a readable Microdesign file, a shell, and the Netpbm package. This workflow only reads the source and writes a new PBM file; it does not need sudo. Reach for elevated privileges only if your normal account genuinely cannot read the input or write the chosen output directory.

1. Check the installed command

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

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

The version output carries build details alongside the version number. The installed manual documents the command as mdatopbm [-d] [-i] [--] [mdafile]. Keep that local manual in mind when moving a script to another Netpbm release: this guide describes the behaviour verified on the installed version.

2. Convert a file to a new PBM

Pass the input path as the final argument and redirect standard output to a new destination:

$ mdatopbm /path/to/source.mda > converted.pbm

The same command accepts a Microdesign .mdp file:

$ mdatopbm /path/to/source.mdp > converted.pbm

mdatopbm writes the PBM image to standard output, so a successful conversion normally produces no progress message. The shell creates or truncates converted.pbm before the program starts, which makes the filename important: redirect to a new name while testing rather than risk a useful existing image.

Check the exit status immediately after the conversion:

$ printf '%s\n' "$?"
0

A zero status means the program completed. It does not prove you chose the right source file or that the image looks correct, so continue with the file checks below.

3. Verify the PBM output

Use file to check that the output is recognised as a bitmap and to see its dimensions:

$ file converted.pbm
converted.pbm: Netpbm image data, size = 640 x 200, bitmap, rawbits

The wording can vary between versions of the file utility. What matters is that the file is identified as Netpbm image data, its type is a bitmap, and the dimensions are plausible for the source.

For a second, format-specific check, ask Netpbm's image tools to read the result if one is installed. pbmfile, for example, reports PBM metadata without changing the image:

$ pbmfile converted.pbm
converted.pbm: 640 by 200 bit, rawbits

If your installation lacks pbmfile, the file check is still useful. Do not open a raw PBM in a text editor and mistake binary pixel data for corruption.

4. Correct Microdesign's display aspect ratio

MicroDesign files use an aspect ratio that can make the converted bitmap look too short on a modern display. Add -d to double the output height:

$ mdatopbm -d /path/to/source.mda > converted-tall.pbm
$ file converted-tall.pbm
converted-tall.pbm: Netpbm image data, size = 640 x 400, bitmap, rawbits

This is a height correction, not a general resampling command: the width stays the same and the output height doubles. Compare the two files in your image viewer and keep whichever matches the intended appearance.

5. Invert the black and white pixels when needed

Use -i when the source's foreground and background need swapping:

$ mdatopbm -i /path/to/source.mda > converted-inverted.pbm
$ file converted-inverted.pbm
converted-inverted.pbm: Netpbm image data, size = 640 x 200, bitmap, rawbits

The option changes the colours used in the result. It does not alter the Microdesign file. Combine the documented short options if you need both the aspect correction and inversion:

$ mdatopbm -d -i /path/to/source.mda > converted-tall-inverted.pbm

6. Read from standard input or handle a leading hyphen

Omit the filename to make mdatopbm read the Microdesign data from standard input, useful in a pipeline where another trusted command supplies the file:

$ cat /path/to/source.mda | mdatopbm > converted.pbm

For a regular file, passing the path directly is easier to audit. Either way, keep the source intact and verify the destination afterwards.

If the input filename itself begins with a hyphen, use -- before it so it is not read as an option:

$ mdatopbm -- -archive.mda > converted.pbm

This matters for unusual names. Renaming the file to something clearer is often easier to review, but do not rename a file in an automated workflow unless you have a recovery plan.

7. Avoid losing an existing output

Shell redirection with > is destructive to an existing destination. Write to a temporary name in the same directory, verify it, then replace the old file deliberately:

$ mdatopbm /path/to/source.mda > converted.pbm.new
$ test -s converted.pbm.new && file converted.pbm.new
converted.pbm.new: Netpbm image data, size = 640 x 200, bitmap, rawbits
$ mv converted.pbm.new converted.pbm

8. Diagnose a failed conversion

If the command cannot open the input, inspect the path and permissions without changing anything:

$ ls -l /path/to/source.mda
$ test -r /path/to/source.mda && echo readable

If the output is empty or file does not recognise it, capture the command's error and status again with a fresh destination:

$ mdatopbm /path/to/source.mda > retry.pbm
$ status=$?
$ printf 'mdatopbm status: %s\n' "$status"
$ test "$status" -eq 0 && file retry.pbm

Do not treat a non-zero status as a usable image. Check that the path names the intended Microdesign file, that it is readable, and that the file is not truncated. If the input is valid but the visual result is wrong, compare an ordinary conversion with one using -d or -i; those are the documented transformations.