Build a Photo CD Contact Sheet with pcdovtoppm

You will turn a Kodak Photo CD overview file into a PPM contact sheet, check that the output was created, and optionally convert it to JPEG. Allow about fifteen minutes if the disc is mounted and you know where its overview.pcd file is. The examples use Netpbm 11.5.2 from the installed netpbm package.

You need a readable Photo CD overview file and the Netpbm command-line tools. The commands below read the disc and write a new image; they do not alter the Photo CD. No elevated privileges are normally needed. Use sudo only if your account cannot read the mounted disc or write the chosen output directory.

1. Check the installed command

Confirm which executable will run and inspect the local option spelling. This is a read-only check:

$ command -v pcdovtoppm
/usr/bin/pcdovtoppm
$ pcdovtoppm -help
/usr/bin/pcdovtoppm : Unknown option -help

Usage: /usr/bin/pcdovtoppm [-m W] [-s S] [-a A] [-c N|n] [-f F] [-b|-w] <overview.pcd>

The installed program is Netpbm 11.5.2. Its help uses -m for maximum output width, -s for the maximum size of each image, and -a for the maximum number of images across. The installed manpage's option text contains a conflicting -w entry for width; the executable help and synopsis identify -m as the width option. Use the syntax shown by the installed executable.

2. Locate the overview file

A Photo CD normally exposes its overview file when the disc is mounted. Replace the placeholder path with the actual mount point, then check that the file is readable:

$ PCD_OVERVIEW='/media/PHOTO_CD/overview.pcd'
$ test -r "$PCD_OVERVIEW" && printf '%s\n' 'overview file is readable'
overview file is readable

If that prints nothing, inspect the path and mount without changing anything:

$ ls -l /media/PHOTO_CD/overview.pcd
$ findmnt /media/PHOTO_CD

Keep the path quoted. A shell path containing spaces must remain one argument. If the disc is not mounted, mount it using your desktop or normal system procedure; mounting is outside pcdovtoppm and may require administrator access.

3. Create the contact sheet

Redirect the PPM output to a new file. The command writes the image to standard output, so an apparently quiet successful run is normal:

$ pcdovtoppm "$PCD_OVERVIEW" > overview.ppm
$ printf 'exit status: %s\n' "$?"
exit status: 0
$ file overview.ppm
overview.ppm: Netpbm image data, size ..., pixmap

The dimensions depend on the overview file and the options used. The useful checks are a zero exit status, a non-empty destination and a file identification that describes a PPM or Netpbm pixmap. Do not treat the absence of progress text as failure.

$ pcdovtoppm "$PCD_OVERVIEW" > overview.ppm.new
$ test -s overview.ppm.new && file overview.ppm.new
$ mv overview.ppm.new overview.ppm

The mv is the replacement point. If conversion fails, leave the original file alone and remove the incomplete overview.ppm.new only after checking its name. There is no need to remove the source overview file.

4. Adjust the layout when needed

The defaults are a maximum result width of 1152 pixels, a maximum image size of 192 pixels and six images across. Set only the constraint you need. This example makes a smaller sheet with eight images across:

$ pcdovtoppm -m 768 -s 96 -a 8 "$PCD_OVERVIEW" > overview-compact.ppm
$ file overview-compact.ppm
overview-compact.ppm: Netpbm image data, size ..., pixmap

These are maximums, not promises that every thumbnail will have exactly the requested dimensions. A larger source set may still produce a sheet limited by the width, image size or across count. If the result is too large, reduce the limits and create a separate output file so the first result remains available for comparison.

Use -c N to set a maximum number of colours. Use -c n for no quantisation, which is the installed help's default. Quantisation can reduce output size but may change the available colours. Use -b for the default black background or -w for a white background. The rightmost conflicting background option takes precedence in current upstream documentation, so keep one background choice in a command.

5. Convert the PPM after checking it

PPM is convenient for Netpbm but can be large. If ppmtojpeg is installed, pipe a verified contact sheet into it:

$ test -s overview.ppm
$ pcdovtoppm "$PCD_OVERVIEW" | ppmtojpeg > overview.jpg
$ file overview.jpg
overview.jpg: JPEG image data, ...

This is a separate conversion pipeline. A successful JPEG command proves that the pipeline completed, not that every thumbnail is visually correct. Open the JPEG in an image viewer and keep the PPM until you have checked the contact sheet.

The manual also documents an annotation font with -f FONT, such as -f smallfont.pbm. Use a font file that actually exists and is readable; otherwise leave the default internal font in place. Do not guess a font path from another machine.

6. Diagnose failures without changing the disc

A missing or unreadable overview file produces a non-zero exit status. Capture that status immediately:

$ pcdovtoppm "$PCD_OVERVIEW" > overview.ppm.new
$ status=$?
$ printf 'pcdovtoppm status: %s\n' "$status"
pcdovtoppm status: 1

Check the path with ls -l and test -r. If the output file was created before the failure, treat it as incomplete and do not publish or archive it as a finished image. Rerun to a new temporary name after fixing the input or permissions.

Do not run the converter as root to make a permissions problem disappear. First fix read access to the mounted source or write access to your destination directory using your normal administration policy. The command does not repair a disc, mount a volume or recover missing Photo CD data.