Papers in PDF format

The resolutions available on PCDs are shown in Table 1.
Name Resolution Memory (MB) Comment
Base/16 128 * 192 0,070 Index Print
Base/4 256 * 384 0,28 Preview
Base 512 * 768 1,125 For CD-I
4 Base 1024 * 1536 4,5 Documentation and HDTV-Standard
16 Base 2048 * 3072 18 Digital prints, ¾ A4
64 Base 4096 * 6144 72 Digital prints > A4, exposure
(256 Base 8192 * 12.288 288 Medical diagnostics)
Table 1: Resolutions offered by the PCD
A slide or flatbed scanner may be a good alternative to the PCD, if images are needed immediately.
However, we were not able to achieve the quality set by the Photo CD. We had especially
problems with the dark parts of the image.
Quality was even worse with the Targa+ framegrabber card and a studio camera, that is resolution
was limited, colors were not realistic, and lighting was difficult. This configuration was
not acceptable for Dermatology. However, there are specific applications that use a video
camera together with an optical zoom and a special cold light source with good results.
As digital camera we tested the Kodak DCS 420, which generates good images. We had some
problems with the color adjustment. High quality digital cameras like the Kodak DCS 460 are
still very expensive, whereas low quality cameras are quite cheap. Low quality cameras offer
resolutions usually between fifty thousand pixels and half a million pixels using true color, that
is somehow comparable to a video camera plus framegrabber card. High end cameras allow to
use the usual equipment of a photo studio.
You may want to check the following aspects, when buying a (low end) digital camera:
• Autofocus?
• Zoom?
• Flash?
• Macro (what is the closest distance)?
• Image preview (without computer)?
• Resolution (maximum, different modes)?
• Image compression (quality, different modes, lossless)?
• Power supply, accu?
• Interfaces to computer (SCSI, serial, parallel)?
• Memory?
• Sensitiveness?
• Minimum exposing time (for moving images, for example sports)?
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