Some comments about the Kodak Photo CD^TM

resolution  color  contrast  blooming 

resolution
Im quite satisfied with the resolution of the standard Photo CD. The PCD-file stores the image at five resolutions: 192 x 128 384 x 256 768 x 512 1536 x 1024 3072 x 2048 The left image shows the original slide. The other two images are the red bordered part of the original image. This part correspond to ca. 1.34 x 2.0mm (0.053 x 0.079") of the original. When the complete image is enlarged by this factor of 18 it would result in a print of 43 x 65cm (17 x 25"). The middle image is the raw data of the 3072 x 2048pixel PCD-file without any modifications in size or sharpness. The right image shows this image with digital enhanced sharpness.
original slide from the Photo CD	part of the 3072 x 2048 PCD-file	... with enhanced sharpness

color
The color reproduction is sometimes a bit disappointing because it does not correspond always to the original slide. The example below is of course one of the bad ones and as you can see it is still a lot better than the scan from my scanner. Most times it is quite easy to get back the right colors with a bit color manipulating but it is necessary at almost every image.
original slide from the Photo CD	with corrected colors	scan from a 300dpi flatbed scanner

contrast
The worst results I get with high contrast slides. Bright and dark parts disappear in complete white and black parts. I can't show how the original slide (left image) is looking but I can tell you that the complete banana is yellow with a few brown marks and that it is not washed out like the scan. In the shadow part at the right hand it is not complete black but you can still see the structure of the wood. The big problem with this is that there is no possibility to correct this in any way because white is white and black is black, you can't get back any information. The middle image is another example of a washed out scene. At the right image, a scan from my flatbed scanner, you can see that the original slide is not washed out.
slide with high contrast	Photo CD scan	scan from a 300dpi flatbed scanner

blooming
Another problem is the blooming effect. Bright points affect the CCD pixels in the near neighbourhood and it looks as if the point is blooming. The left image shows the original slide. The middle image shows the blooming effect quite clear and at the right image you can see the result after some digital corrections.
original slide from the Photo CD	enlarged part without any corrections	... with corrections

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last update 25.02.2002