Photo CD

Revision as of 12:28, 15 March 2025

Kodak Photo CD (PCD) is an image file format that was used by products and services which developed photographs by digitizing them and writing them to a CD.

Photo CD files combine six different resolution versions of the original image into a single compressed file.

Designed for 35 mm photography, the original Photo CD Master disc can hold about 100 images, or four, 24-exposure rolls of film. The images are stored using the Photo YCC color encoding metric, developed by Kodak, which stores data at multiple levels of resolution in units called IMAGE PAC files.^[1]

Identification

The ASCII string "PCD_IPI" appears in the file, usually(?) at offset 2048.

Structure

Main image (called "Base") is located at 0x30000 and is in 512x768 resolution, uncompressed and YUV color space. List of resolutions:

192x128 384x256 768x512 1536x1024 3072x2048 6144x4096

Converting PCD to other formats

PCD files contain multiple resolutions and have other subtitles that tools must be aware of. This page discusses tool support, and recommends pcdtojpeg over ImageMagick, which had flaws at that time. It seems that later versions of ImageMagick have dealt with the colour blow-out issues.

Note that, when converting PCD files using ImageMagick, you must manually select the resolution layer you want. e.g.

$ convert BlownJohn.pcd[0] BlownJohn-0.png
$ convert BlownJohn.pcd[1] BlownJohn-1.png
$ convert BlownJohn.pcd[2] BlownJohn-2.png
$ convert BlownJohn.pcd[3] BlownJohn-3.png
$ convert BlownJohn.pcd[4] BlownJohn-4.png
$ convert BlownJohn.pcd[5] BlownJohn-5.png
$ convert BlownJohn.pcd[6] BlownJohn-6.png
$ convert BlownJohn.pcd[7] BlownJohn-7.png
$ convert BlownJohn.pcd[8] BlownJohn-8.png

However, examining the results, we can see that some of these are the same:

$ ls -l BlownJohn-?.png
     52322  BlownJohn-0.png
     52322  BlownJohn-1.png
    191840  BlownJohn-2.png
    707221  BlownJohn-3.png
   2476659  BlownJohn-4.png
   9668328  BlownJohn-5.png
  28572165  BlownJohn-6.png
  28572165  BlownJohn-7.png
  28572165  BlownJohn-8.png

i.e. (0,1) are identical, as are (6,7,8), with (1) being the lowest resolution and (6) being the highest. This is consistent with the six resolutions that should be present in the PCD. For the highest resolution, use this:

$ convert BlownJohn.pcd[6] BlownJohn.png

The pcd2html tool may also be useful.

Sample files

• http://cd.textfiles.com/prettywomen/IMAGES/
• http://www.fileformat.info/format/photocd/sample/index.htm (file uses a PICT wrapper)
• Kodak PhotoCD Sampler Disc Image
• dexvert samples — image/pcd

Libraries

• PCD unit for Delphi/Lazarus - library in Pascal

Software

• Tom's Viewer
• XnView

External Links

• Wikipedia article
• Kodak Photo CD web page
• Kodak Image Pac Learning (archived)
• Kodak Photo CD File Format Summary, from the Encyclopedia of Graphics File Formats
• Encyclopedia of Graphics File Formats Chapter on PCD
• PCD Developers Info

References

1. ↑ https://web.archive.org/web/19961227013151/http://www.kodak.com/digitalImaging/aboutPhotoCD/aboutPCD5.shtml