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Old 10-15-2007, 09:34 AM   #81
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Scanner vs compact cameras

Following my earlier post, below are further test results including two models of compact Casio cameras.

Setup: since I do not touch my tripod and Canon Powershot Pro 1 anymore to avoid lengthy angles adjustment afterwords, for testing Casio I used a superclamp with a headball, attached to the back of a chair and my v-cradle put on the seat of the chair over a cardboard box. I took the photos outdoors (picture attached).

The settings:
1. HP scanjet 2300c 300 dpi color
2. Canon Powershot Pro 1, 8 Mpixels, resolution 3264 x 2448, sensor ccd 2/3" (8.80 x 6.60 mm), indoors with halogen 50 watt lamp, white balance set to tungsten, other settings automatic
3. Casio Ex-Z1000, 10.1 Mpixels, resolution 3648x2736, sensor ccd 1/1.8 " (7.18 x 5.32 mm), outdoors in shadow, white balance set to custom based on white sheet of paper, other settings automatic
4. Casio Ex-Z850, 8.1 Mpixels, resolution 3264 x 2448, sensor the same as Ex-Z1000, outdoors in sunlight, automatic white balance, other settings automatic.

The picture attached (margins trimmed.jpg) shows in the top row images from the scanner and the Canon, and in the bottom row images from Ex-Z1000 and Ex-Z850. Apparently my custom white balance setting for Ex-Z1000 was wrong (I used a white sheet of paper instead of Kodak gray card. However a white sheet works for me indoors) .

The details in the attached picture "detail.jpg" show that rendering of fonts with camera photos was in all cases better than in the scan (download and see the picture full screen). The images are in sequence 1 to 4 from top to bottom.

OCR results with Finereader 8 (no preprocessing of pictures)

1. scan - uncertain characters 82, total characters 2130; error rate 4%
2. Canon - uncertain characters 44; total characters 2093; error rate 2%
3. Ex-Z1000 - uncertain characters 52; total characters 2100; error rate 2%
4. Ex-Z850 - uncertain characters 80; total characters 2133; error rate 4%

The pdfs saved as text and images are attached in the last picture.

- The results from a compact Ex-Z850 camera are comparable to those from the 300 dpi scan.
- Canon (8 Mpixels) gives better results than Ex-1000 (10.1 Mpixels) because of a larger sensor.
- The higher resolution (10.1 Mpixels) Casio gave better results than 8.1 Mpixels Casio, despite the same sensor size (however, it is not as good as 8.1 Mpixels Casio when focusing under dim condtions).

BTW. I have no time to deal with RAW, so I save pictures as the biggest size jpgs (compressed in the camera). Typical sizes are 2 to 4 MB.
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Last edited by ereszet; 10-15-2007 at 02:02 PM.
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