Kodak's Photo CD system, originally intended for consumer applications, has been used successfully by museums and libraries to store digital images from scanned film, prints and documents. With recent advances in digital image standards and their anticipated adoption by cultural institutions, questions arise as to how best to convert Photo CD image files. We describe both the file format and colorimetric definition of image data stored on a Photo CD disc. Particular attention is paid to retaining the full range of encoded subject luminance values, and compatibility with methods for exchange and display of digital images. The requirements for migration are discussed in terms of retention of subject color information. From this it is possible to evaluate various options for digital migration.