recommended prescan saturation settings (Epson 4870)?

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false_dmitrii

I'm still as much of a scanner & image editing novice as when I first
posted here. Since various circumstances have kept my film scanner
purchase on hold, I went ahead and picked up an Epson 4870 to get some
practice working at lower resolutions...needed a flatbed anyway.
Having read so much about the limitations of ICE, I don't know why I
suddenly assumed it would solve the dust problem for non-transparent
sources.... :P

I'm using Epson Scan while evaluating my overall scan software needs.
I don't have an ICC target so am sticking with the provided Epson
profile. Colors look very close to the originals; I can't tell if the
slight variance is due to the profile itself or the fluorescent
lighting. Obviously, a custom profile could fix this in either case.

However, all scans also appear desaturated, presumably related to
either the light source or the sensor color sensitivity. I'm working
out of necessity on an LCD, which might have more saturation impact
than I realize. But printouts have looked fine, so I think I'm
judging the saturation correctly.

I'm curious whether boosting the saturation in Epson Scan merely adds
post-processing or actually adjusts the way Epson imports the data. I
assume the latter would give smoother, more accurate results. Setting
saturation to "50" or so seems to bring the image close to normal,
whereas similar numbers in image editors produce wild color
distortion.

Is the saturation control likely re-aligning the scan sensitivity in
the manner of pre-scan histogram and focus adjustments (no focus
control in Epson, of course)? Or is it just performing a post-scan
software-only boost at a lower strength than most image editors? If
the latter, it would be easier to save saturation adjustment for
later. Would a custom color profile fix saturation too? I'm striving
for the best initial capture without unintentionally discarding or
altering data.

Does saturation adjustment have a destructive effect on image data in
the first place?

I hope my descriptions make sense. My knowledge on scanner issues
derives entirely from some months of reading this group and related
websites; apologies for any misconceptions.

false_dmitrii
 
I'm still as much of a scanner & image editing novice as when I first
posted here. Since various circumstances have kept my film scanner
purchase on hold, I went ahead and picked up an Epson 4870 to get some
practice working at lower resolutions...needed a flatbed anyway.
Having read so much about the limitations of ICE, I don't know why I
suddenly assumed it would solve the dust problem for non-transparent
sources.... :P

I'm using Epson Scan while evaluating my overall scan software needs.
I don't have an ICC target so am sticking with the provided Epson
profile. Colors look very close to the originals; I can't tell if the
slight variance is due to the profile itself or the fluorescent
lighting. Obviously, a custom profile could fix this in either case.

However, all scans also appear desaturated, presumably related to
either the light source or the sensor color sensitivity. I'm working
out of necessity on an LCD, which might have more saturation impact
than I realize. But printouts have looked fine, so I think I'm
judging the saturation correctly.

I'm curious whether boosting the saturation in Epson Scan merely adds
post-processing or actually adjusts the way Epson imports the data. I
assume the latter would give smoother, more accurate results. Setting
saturation to "50" or so seems to bring the image close to normal,
whereas similar numbers in image editors produce wild color
distortion.

Is the saturation control likely re-aligning the scan sensitivity in
the manner of pre-scan histogram and focus adjustments (no focus
control in Epson, of course)? Or is it just performing a post-scan
software-only boost at a lower strength than most image editors? If
the latter, it would be easier to save saturation adjustment for
later. Would a custom color profile fix saturation too? I'm striving
for the best initial capture without unintentionally discarding or
altering data.

Does saturation adjustment have a destructive effect on image data in
the first place?

I hope my descriptions make sense. My knowledge on scanner issues
derives entirely from some months of reading this group and related
websites; apologies for any misconceptions.

false_dmitrii
Click to expand...
All adjustments to color, brightness, sharpness, etc. are post
processing whether done using the scanner software or an image
editor. Epson claims that they have 7 levels of brightness which
can be adjusted by setting the gamma. It is not clear if this
affects the scanning exposure, it seems unlikely that they can
actually change the brightness of a fluorescent bulb.
Several scanner software packages do the post processing at 8 bits
even if the output is set for 16 (Minolta, for example).
I've not done any real tests using the Epson software, but Vuescan
and Silverfast do true 16 bit processing.
 
false dimitri,
I think the point to keep in mind is that any scanner, film or flatbed is
'only' a camera and, like any camera, you really only control focus and
exposure. Everything else will be done post scan by software. You take
your choice whether you put your trust in the scanner software or an editing
programme like Photoshop. I think people delude themselves that because
they make involved selections pre-scan they are necessarily getting a
'better' scan. Settings to capture the maximum data, that is basically
exposure to make sure you are not clipping either end of the scale, are
essential pre-scan. After that, any selection will surely involve
destruction of data - though not necessarily be detrimental to the finished
image.
John
 
Robert Feinman said:
All adjustments to color, brightness, sharpness, etc. are post
processing whether done using the scanner software or an image
editor. Epson claims that they have 7 levels of brightness which
can be adjusted by setting the gamma. It is not clear if this
affects the scanning exposure, it seems unlikely that they can
actually change the brightness of a fluorescent bulb.
Several scanner software packages do the post processing at 8 bits
even if the output is set for 16 (Minolta, for example).
I've not done any real tests using the Epson software, but Vuescan
and Silverfast do true 16 bit processing.
Click to expand...

Thanks, Robert (& John), that clarified what I should have known
already. With a 16bit scan, then, the important thing is to make the
initial (and preferably only) color and brightness adjustments in a
16bit environment, be it the scanner's postprocessing software or a
capable image editor? Thanks to its reputation, I'm sure to give
Vuescan a try once I'm comfortable with the basic scanner tools. May
also look into Silverfast AI full version...does anyone here find it
superior to VS?

If you can point me to relevant instructions, and it can be done
without special plugins or knowledge, I'm willing to test the Epson
software for 8 vs 16bit processing. Would it mean comparing a 16bit
scan adjusted via Epson to a raw scan adjusted in a 16bit editor?

Epson's software offers "24bit" and "48bit" options. I'm assuming
these correspond to the 8bit and 16bit levels normally referred to in
current discussions? Is 48bit simply 3 16bit color channels? I'm
really ignorant about this. :)

Still curious as to the "normality" of marked undersaturation in an
unadjusted/generic profile flatbed scan, and whether color profiling
is the preferred way to address it.

false_dmitrii
 
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