Extract a Palm Image Viewer Picture with pdbimgtopam

pdbimgtopam pulls the picture out of a Palm Pilot Image Viewer PDB and writes it as a PAM that any Netpbm tool can read. It can also save the image's note text, if the PDB has one. Allow about fifteen minutes: the conversion itself is quick, but checking the binary output and picking a safe destination deserves care.

You need Linux, a readable Palm Image Viewer PDB file, and the Netpbm package. The installed command checked for this guide is Netpbm 11.5.2, built from source dated 31 March 2024. The local manual page is dated 25 September 2010, so what follows describes this installed command and its documented interface, not every historical or future Netpbm build.

1. Check that pdbimgtopam is available

Run this as your ordinary user. Conversion needs no elevated privileges, since it only reads the input and writes files where you already have permission.

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

The installed program prints more build information after the version line. If command -v finds nothing, install Netpbm through your normal package manager before continuing; there's no need for sudo to run this conversion itself.

2. Convert the PDB image to PAM

Redirect standard output to a new filename. The input argument is optional: leave it off and pdbimgtopam reads the PDB data from standard input instead.

$ pdbimgtopam /path/to/palm-image.pdb > palm-image.pam

A successful run normally leaves the terminal quiet and just creates the PAM file. It doesn't replace the PDB input. Redirection is a different matter, though: the shell truncates an existing palm-image.pam before the converter even starts, so choose a new name if the old output matters.

For a pipeline, or a program that supplies the PDB on standard input, drop the filename entirely:

$ cat /path/to/palm-image.pdb | pdbimgtopam > palm-image.pam

The pipeline form suits a PDB that's already being read by another command. For a plain file, the direct form is easier to review, because it makes the input explicit.

$ pdbimgtopam /path/to/palm-image.pdb > palm-image.pam
$ printf '%s\n' "$?"
0

3. Verify the PAM header before opening it

PAM is a binary-capable Netpbm format. Its header is readable text, but the pixel data that follows isn't, so inspect only the first lines and leave the rest to a format-aware tool.

$ sed -n '1,7p' palm-image.pam
P7
WIDTH 160
HEIGHT 160
DEPTH 1
MAXVAL 1
TUPLTYPE BLACKANDWHITE
ENDHDR

Your own dimensions will depend on the Palm image. What matters: the P7 magic value, a plausible width and height, DEPTH 1, and an ENDHDR line. The installed command emits grayscale PAM output. For a monochrome Pilot image, the documented maximum value is 1; the manual also documents maxval 255 for non-monochrome input, while noting that Pilot images are always monochrome.

Use file as a second, non-destructive check:

$ file palm-image.pam
palm-image.pam: Netpbm image data, size 160 x 160, 1-bit grayscale, rawbits

The exact wording can vary with the file database on your system. It should identify a Netpbm image and report dimensions matching the PAM header. A zero-byte or unexpectedly small file means a failed conversion, even if a shell pipeline hid the converter's exit status from you.

4. Preserve an image note when one exists

PDB Image records can carry a note. Without an option, pdbimgtopam just ignores it. Pass -notefile= with a separate destination to save it:

$ pdbimgtopam \
    -notefile=/path/to/palm-image.note \
    /path/to/palm-image.pdb > palm-image.pam

The option name includes an equals sign, followed by the note filename. The image still goes to standard output; the note goes to the file named by -notefile. If the PDB has no image note, don't assume a note file proves the image conversion succeeded: check the PAM output and exit status too.

Keep the note separate from the PAM file. It's metadata extracted from the PDB, not part of the PAM image stream, so concatenating the two would make neither one a reliable standalone result.

5. Avoid losing an existing conversion

Shell redirection isn't transactional. To keep an earlier PAM file while testing a new conversion, write to a temporary name in the same directory and swap it in only after verification:

$ pdbimgtopam /path/to/palm-image.pdb > palm-image.pam.new
$ test -s palm-image.pam.new
$ sed -n '1,7p' palm-image.pam.new
$ mv -- palm-image.pam.new palm-image.pam

That mv changes the directory entry, so run it only once the new header and dimensions check out. If conversion or verification fails, leave the original file alone and remove just the incomplete palm-image.pam.new after confirming it's the disposable file; never use a wildcard with rm for cleanup.

If you need to recover after an accidental overwrite, restore the destination from a backup or filesystem snapshot. pdbimgtopam can't reconstruct a PAM file that's already been truncated, though the original PDB stays unchanged and can always be converted again.

6. Diagnose the common failures

An input-open error usually means the path is wrong or the file isn't readable. Inspect it without changing anything:

$ ls -l -- /path/to/palm-image.pdb
$ test -r /path/to/palm-image.pdb && printf '%s\n' 'input is readable'

If the command reports malformed PDB data, check that the file is actually a Palm Pilot Image Viewer PDB containing an Image record. A generic Palm database isn't automatically a supported input. Keep a copy of the original while you investigate.

If the terminal fills with diagnostic detail, rerun without -verbose. That option is for inspecting the PDB Image header and processing information; it doesn't make the converter more compatible. Use it when you need to see the stored title, dimensions, pixel packing or other input details:

$ pdbimgtopam -verbose /path/to/palm-image.pdb > palm-image.pam
pdbimgtopam: PDB IMAGE header:
pdbimgtopam:   Width: 160
pdbimgtopam:   Height: 160

The exact verbose fields depend on the PDB. Standard error carries these messages, so the PAM data stays on standard output when you redirect it as shown; don't redirect both streams into the PAM file.