A client who recently upgraded discovered that she can no longer open Kodak Photo CD scans in Photoshop CS4. She asked if there was any way to make this work.
Quick summary of the situation:
Kodak has stopped supporting Photo CD and the related plug-ins so Adobe stopped including the plug-ins with Photoshop CS4.
If you are fortunate enough to have a Photoshop CS3 installation DVD, you can retrieve the CS3 plug-in from there and install it in Photoshop CS4. This will work with Windows XP and Vista, and on non-Intel Macs.
If you have an Intel Mac, you need to run Photoshop under Rosetta to use the plug-in.
Other conversion possibilities:
The latest version of GraphicConverter, a low-cost Macintosh shareware program, will convert Photo CD images into other standard formats such as JPEG or TIFF.
Apparently some versions of iPhoto will open PhotoCD images (iPhoto '08 doesn't on my Intel Mac).
Pcdtojpeg is a Macintosh and Windows command-line conversion program for converting Photo CD images to JPEG format.
Other helpful links: