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Old 10-14-2007, 04:06 PM   #77
ereszet
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Join Date: Sep 2007
Device: Sony PRS-500 Archos 704 wifi
The proof is in the pudding

It is time to present some comparison results scanner vs. camera.
The scanner is hp scanjet 2300c at 300 dpi color.
The camera setup is Canon Powershot Pro 1 on a tripod, v-cradle put on a box to bring it closer to the lens, a home 50 watt lamp with halogen mini bulb - about 1.5 meters over the cradle, a diffusor for dissipation of light - about 40 centimeters below the bulb (see my first posts in this thread).

Neither the scanner nor the photo setup are top quality devices/arrangements. It is just what I have at hand in my temporary residence away from home.

The scanning took a lot of time (between 30 and 60 seconds if not more - I didn't look at my watch).
The photo took a split second plus a dozen or so seconds to download the image to my computer. All camera parameters apart from zoom and white balance were automatic. White balance was set to "tungsten". No attempt was made to set the custom white balance, based on a Kodak gray card (or a white sheet of paper).

The object to scan and photo was a DVD plastic reflective case with a sleeve cover underneath and miniscule text in 10 languages. See the attached picture "original scan and photo.jpg" (lefthand image is scan, righthand image is photo).

The black margins from both the scan and the photo were removed manually. See the attached picture "images with black margines removed.jpg" (lefthand image is scan, righthand image is photo). The colors are not true neither in scan (too blueish) nor in photo (too greyish). The white is more white in the scan (possibly can be made better in the photo with custom white balance settings or with postprocessing). The photo shows a small barrel distortion due to the object being close to the lens. My camera would not allow me to zoom from a further distance (automatic focus would not work; I have not tried to use the manual focus since it is awkard and cumbersome to use in Powershot Pro 1 - despite a nice ultrasonic ring that can be rotated manually, one needs to push some buttons at the same time, which requires three hands).

The quality of images can be seen in detail in the attache picture "scanner and photo detail.jpg" (top image is scan, bottom image is photo). Amazingly, the photo renders the fonts much better than the scan.

The OCR results with Finereader 8 are (out of 10 languages, two were not installed in my recognition engine):
scan - uncertain characters 82, total characters 2130; error rate 4%
photo - uncertain characters 44; total characters 2093; error rate 2%

To make the OCR results visible, I saved the results as text and image. See the attached "text and image picture" (lefthand image is scan, righthand image is photo - both after OCR). Usually, I save text under image, which preserves picture true copy of the original.

What arrangement wins? In my opinion, both for speed and quality the camera is better. But you can draw your own conclusions.

As a bonus, I include an example of OCRed photo of text on a Scan Reader screen (original at the top, OCRed "text over image" at the bottom of the picture). That the result is perfect is just accidental. You can expect some OCR errors with other texts.
Attached Thumbnails
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