|
TESTS OF PRO-PALETTE 8000 FILM RECORDER Prof. John Hart Program in Atmospheric and Oceanic Sciences University of Colorado Boulder, CO 80302 May 2005 nimbus.colorado.edu/hart/science.htm
Tests of a film recorder used to makes slides from digital files. Shab Levy was kind enough to run a few large digital files through the Cascade Stereo Club Polaroid Pro-Palette 8000 film recorder. I was interested to see how such 35mm slides might compare with other film recorders I had tried in Boulder professional photo laboratories. These were the MGI Sapphire 4K CRT, the Lightjet 2000 laserwriter, and the Lasergraphics LFR 8K CRT film recorders. Some information on how the MGI and the Lightjet did has been reported earlier. They were not spectacular. At the time I concluded you could do almost as well by taking 35mm slides off a good CRT computer monitor screen - after making suitable adjustments in contrast and color, etc. But Shab's initial test slides looked, visually, so good that I was initially quite impressed. I proceeded to do the following to compare slides produced by using the PP8000 with a digital camera image file, and with super high resolution scans of a good film-camera original: Sources: 1) A Velvia 35mm slide digitized using a Minolta 5400dpi film scanner, set for maximum performance (5400dpi, 16bits per color, 8X resampling, manual focus and exposure). Size sent to the recorder was about 6500x4880. 2) A Sony V1 5 megapixel "Fine" digital camera image. Post-processed a little (for sharpness and color), and cropped in the vertical and carefully rezzed up to 3000x2000 for film recording. Analysis: The slides from Shab Levy were re-digitized using the Minolta 5400dpi film scanner set up as described above. The files reproduced by this film scanner are high enough in resolution to see the film grain. Dynamic range of the scanner and color balance are excellent. Film recorder slide 1) was 6522x4758 and the output slide 2) was 7266x4746. These scans were un-retouched in post processing (because all you can really do with them is project or view them as is). Below are presented downsized full frame comparisons, and 100% pixel crops (no resizing, pixel per pixel as shown on your screen). Slide 1 original file:
Slide 1 film recorder output:
Slide 1 original file, crop:
Slide 1 film recorder crop:
Digital Camera Original File:
Film Recorder Output of Digital Camera File:
Digital Camera File Crop:
Film Recorder Crop from Digital Camera File:
Film Recorder Crop from Digital Camera File (all pixels, no bicubic resampling to match sizes): Download full image. CONCLUSIONS: One can draw one's own from this. My initial enthusiasm has waned somewhat. Of course these are hard and difficult images. Lots of dynamic range. White water and a dark wetsuit, etc. Lots of subtle texture and fine detail. But, I think: 1) The colors aren't bad, and could perhaps be corrected to work out better. 2) The dynamic range is quite good, although whites are not as brilliant. 3) There is some loss of fine detail, even in going from the 5 megapixel digital camera file to film. For example, look at the label on the helmet of the waterfall rapper. Based on this, my guess is that projection of similar (~ 5 megapixel) digital camera files, using a really good SXGA+ (4.2 Megapixel) high contrast digital projector, will actually look quite a bit better than projection of such film recorder slides using traditional Ektagraphic style slide projectors. Since I don't have such a digital projector (but have tested some in other venues), I can't be sure of this rash statement. However, the colors of such digital projectors are much better than the muddy tones put out by such slide projectors, and there will be no loss of resolution at all (while there does appear to be a fair bit lost here in going from digital camera files to film recorder output). The film recorder does seem to do better with high contrast graphics arts images like titles, computer generated figures, and the like (not shown here). I think it has a real use in allowing slide presentation of computer-constructed images, which often do not have the fine texture, dynamic range, and detail of the images tested here. | ||||||||||||||||||
