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Journal mburns's Journal: Using my Canon CanoScan FS 2710 film and slide scanner for old slides 1

This film and slide scanner beats out the device I bought by Wolverine Tech that snaps a digital picture of my negatives and slides. The Canoscan FS 2710 has no vignetting and no ill considered custom color curve that must be undone in post processing.

It is able to capture from warped slides. No holder is require for slides; just insert them individually for scanning. The scanner is supported by my Linux computer with no added software. I added the required SCSI PCI internal card and cable to my desktop computer, again with no added software.

But still, it is a challenge to do the post processing needed to get good color from old slides with any scanner. I suspect that no scanner has the automation to do this well.

I scan from within Gimp software with the Xsane plugin, turning off and resetting all of the auto levels, using the color and full color range settings, and then making for each slide a custom four point color curve for each color - red, green and blue. The green curve stays closer to the diagonal; I pin the middle third of the green curve exactly to the diagonal. The middle thirds of the red and blue curves are adjusted down from the diagonal line to eliminate a magenta tint as a next to last step.

But first for each color I pin the middle third of the curve to thediagonal, and then move the lower left point along the bottom into the base of the histogram, green adjusted the least and blue the most as required by the faded slide. This makes for for realistic dark colors.

Next I move the top right points along the top closer to the right edge of the histogram in order to make accurate bright colors, again green adjusted the least and blue the most.

Now I move down the middle thirds of the red and blue curves to fix the faded magenta look. The curves still run parallel to the diagonal line, and blue is adjusted down more than red. You can add extra tilt to this part of the blue curve if the darker medium colors are still bluish and the lighter warm tinted.

Last I might make four points for the value curve in order to adjust the tilt of the middle. I would reduce the slope in the middle section to reduce harsh contrast to a realistic level, and then lower that middle section downward to compensate for the overall fading.

Michael J. Burns

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Using my Canon CanoScan FS 2710 film and slide scanner for old slides

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  • I would now narrow the middle section of the blue curve rather than increasing the slope. The settings for bright colors at the top right of the curves might not be so symmetric as I assumed above, since bright colors depend more on the transparency of the slides than on the faded dyes that count for dark colors.

Mathemeticians stand on each other's shoulders while computer scientists stand on each other's toes. -- Richard Hamming