Writing your own CD-ROM photo library disks

The latest method for distributing your photographs - or delivering them to your customer - is the ISO 9660 format CD-ROM. It's common to most of the personal computers being sold today with the tag 'multimedia'.

ISO 9660 is a restrictive standard. File names are limited to eight characters, one full point, and a three-character extension. Characters are limited to capital letters A-Z, numbers 0 to 9, and a few special symbols. Spaces are replaced_with_an_underline. ISO 9660 file structure is limited to eight levels - any more folders-within-folders will be invisible.

Given that most image storage is on Macintosh, which has always allowed freedom in 32-character naming without the need for filetype extensions and an almost bottomless depth of nested folders, PageMaker and XPress files can need a huge amount of work before they become ISO 9660 compliant. Linked files must first be re-named, then the links in the main files must be rebuilt.

There are two ways of doing this. Working as outlined above, the Mac (or Unix, or Windows 95, etc) data becomes ISO 9660 compliant. You can then write a plain ISO 9660 CD-ROM, and subject to cross-platform data format compatibility, your work will be available to any type of computer with a CD-ROM drive.

Alternatively, you can create a set of re-named 'aliases' and leave the original long file names untouched. This works for archives such as clip-photo disks, but not for DTP files with links.

Doing this work to create a cross-platform CD-ROM is time-consuming. The final job is to put all the data on to a newly formatted, fast hard disk drive so that it is entirely unfragmented. This is then used by the CD-ROM mastering software (we use Astarte Toast Pro) to create a small ISO 9660 'image' file on another clean, unfragmented disk volume. Finally, the software checks drive speeds and data transfer integrity, and you can 'burn' your CD-ROM with up to 650Mb of data.

Our CD-R writer at Icon is a Yamaha CD-R 100 II Quad Speed external SCSI. It takes around 15 minutes to create each full CD-ROM copy, compared to double-speed drives which take a predictable 30, and the original models which can take an hour. The new very cheap CD-R writers, costing under &sterling;1,000, are double speed at the best (Hewlett Packard) and sometimes single speed (earlier JVC and Pinnacle models being sold by a few dealers). Some are not compatible with all file formats, or with multi-session adding of files at later dates to partly filled CDs.

For commercial distribution, the compatibility of ISO 9660 filenames must be combined with the ability to search for images by content, name, photographer, location or other parameters. A good image-database like Kodak Shoebox, Canto Cumulus or Adobe Fetch must be used to build a 'browser' with thumbnails linked to the high-res images. You are often allowed to distribute a viewer application free of charge, or turn the data file into a runtime application (one which runs itself but can't be changed).

My personal opinion is that Netscape is probably as good a browser engine as any dedicated package. Apparently anyone who doubts the abilities of Netscape, and its future, should take a look at the Encyclopedia Britannica CD-ROM Edition - it's written entirely to run from a regular copy of Netscape and as a result packs around three times as much info on to it as any comparable CD to date.

The availability of high quality quad-speed CD-ROM writers like the Yamaha (around �2,000 plus �295 for Toast Pro software) makes it possible for photographers to publish or deliver their work in this versatile format. CD-ROM blank disks costs around &sterling;8 each and prices are falling.

Do not think, however, that these 'gold master' CDs - original copies - are durable. Like Photo-CDs, they can be rendered unusable by a scratch. Many people make the mistake of handling Photo-CDs like audio CDs and find out too late that a glitch in data is a very different matter from a glitch in the soundtrack.

� David Kilpatrick