Convert PBM Images to Epson Printer Streams with pbmtoepson

pbmtoepson turns a PBM bitmap into Epson printer control data you can inspect before you trust it near an actual printer. The examples use Netpbm 11.5.2 from package netpbm 2:11.05.02-1.1build1 on this machine.

Allow about fifteen minutes. You need a readable PBM file and the Netpbm tools. A printer is optional for this guide. Keep the first output in an ordinary file: printer streams are binary control data, not an image format you can sensibly inspect in a text editor.

1. Check the installed command

Confirm the command is installed and record the version before trusting any example. These are read-only commands, no elevated privileges needed:

$ command -v pbmtoepson
/usr/bin/pbmtoepson
$ pbmtoepson --version
pbmtoepson: Using libnetpbm from Netpbm Version: Netpbm 11.5.2
...
$ dpkg-query -W -f='${Package} ${Version}\n' netpbm
netpbm 2:11.05.02-1.1build1

The installed manual describes four command-specific controls: -protocol=escp9 or -protocol=escp, -dpi=n, -adjacent, and -nonadjacent. Netpbm also accepts common libnetpbm options such as -quiet, using a single hyphen throughout.

2. Prepare a small PBM test

Use a tiny monochrome PBM for checking the pipeline. Plain PBM syntax is portable enough to pipe through standard input with no source file at all:

$ printf 'P1\n8 8\n0 0 1 1 1 1 0 0\n0 1 0 0 0 0 1 0\n1 0 1 0 0 1 0 1\n1 1 1 1 1 1 1 1\n1 1 1 1 1 1 1 1\n1 0 1 0 0 1 0 1\n0 1 0 0 0 0 1 0\n0 0 1 1 1 1 0 0\n' > /tmp/test-pattern.pbm

That's temporary test data under /tmp. For a real image, swap in the PBM file you already have, and don't assume a bitmap-looking extension means PBM: check with file if you're unsure:

$ file /path/to/input.pbm
/path/to/input.pbm: Netpbm image data, size 8 x 8, ASCII bitmap

The exact wording varies with the PBM variant. What matters is that it's identified as Netpbm bitmap data and is readable.

3. Convert to a file first

Run the converter with explicit settings and redirect standard output to a file. This example picks the newer ESC/P protocol at 60 dots per inch:

$ pbmtoepson -protocol=escp -dpi=60 /tmp/test-pattern.pbm > /tmp/test-pattern.escp
$ printf 'exit status: %s\n' "$?"
exit status: 0
$ wc -c /tmp/test-pattern.escp
20 /tmp/test-pattern.escp

pbmtoepson reads the named PBM file and writes Epson graphics to standard output; omit the filename and it reads standard input instead. The output is not a PBM, PDF or ordinary raster file, it's a printer stream of control bytes and image data.

4. Inspect and verify the stream

Check the output is non-empty and begins with plausible Epson control bytes. This is not a full printer compatibility test:

$ xxd -g1 -l 32 /tmp/test-pattern.escp
00000000: 1b 41 08 1b 2a 00 08 00 3c 5a bd 99 99 bd 5a 3c  .A..*...<Z....Z<
00000010: 0a 0c 1b 40                                      ...@
$ test -s /tmp/test-pattern.escp && echo 'stream is non-empty'
stream is non-empty

Your bytes will change with the input image, protocol, density and dot-printing mode. A zero exit status means the conversion completed, not that a particular Epson model will accept the stream.

For a pipeline, the equivalent form is:

$ pbmtoepson -protocol=escp -dpi=60 < /path/to/input.pbm > /tmp/output.escp

Standard input is handy in scripts, but it hides the source when you come back to the command later, so prefer a named input file while diagnosing a failed conversion.

5. Choose protocol and density deliberately

Use -protocol=escp9 for the older ESC/P 9-pin protocol or -protocol=escp for the newer ESC/P protocol. The manual points modern ESC/P2 printers to the separate pbmtoescp2 program instead. Don't pick escp just because the printer is an Epson: check the model's own protocol documentation.

The accepted -dpi values are exactly 60, 72, 80, 90, 120, 144 and 240, controlling horizontal print density:

$ pbmtoepson -protocol=escp9 -dpi=120 /path/to/input.pbm > /tmp/output-escp9.120dpi

Omit -dpi and the program picks a density consistent with your other options, which is convenient but less reproducible in a script. An unsupported value fails outright before anything useful gets produced:

$ pbmtoepson -dpi=61 /path/to/input.pbm > /tmp/invalid.escp
pbmtoepson: Invalid DPI value: 61. This program knows only 60, 72, 80, 90, 120, 144, and 240.

Leave -adjacent and -nonadjacent unset for a first test. The program defaults to adjacent dot printing unless that clashes with your other choices. Add one only when the printer or the appearance of the output actually gives you a reason to, and never use both together.

6. Recover from common failures

A non-zero exit status usually points to an unreadable or invalid PBM, an unsupported density, or a bad option. Read the diagnostic before reaching for permissions changes or sudo:

$ test -r /path/to/input.pbm && echo readable
$ pbmtoepson -dpi=240 /path/to/input.pbm > /tmp/output.escp
$ printf 'exit status: %s\n' "$?"

If the output is wrong for the printer, keep the PBM and remove only the generated stream, after checking nothing else is using it:

$ rm /tmp/output.escp