Scanning Grayscales for reprinting

MM
Posted By
M_McCallum
May 12, 2005
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381
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7
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Closed
Scanning book grayscales at 600dpi for reprinting at the same. End published result always looks grainy and less shade defined than the scan/orig. I wonder how the screen on the orig printed image effects this or is the problem is in house. I appreciate any help.
Mike
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T
Tommo
May 13, 2005
Does it look like it has a kindof grainy grid lines running through it?
MM
M_McCallum
May 13, 2005
Sorry about the double post…
Using both PS6 and CS. No matter with either.
MM
M_McCallum
May 13, 2005
no scan lines. just the end published result is like the shade is less exact/accurate and it looks like it is screened- if you know what I mean…
R
RSD99
May 13, 2005
FWIW:
It usually requires something like 2400 dpi … or even higher … to get a "clean" scan of type. Scanning halftones can be a "whole ‘nother can of worms." I would suggest that you get a screen ruler, determine what halftone screen angle and frequency, and scan at some multiple of those figures.

Additionally, some printshops use "copydot" scanning to scan whole pages, including halftones … and that requires scanning at *exactly* the dpi that the original (negatives) used when they were imaged. This can be as high as 5000 dpi, but is often somewhere around 3200 dpi.

Therefore:
I suggest that you increase your scan resolution.

wrote in message
Scanning book grayscales at 600dpi for reprinting at the same. End
published result always looks grainy and less shade defined than the scan/orig. I wonder how the screen on the orig printed image effects this or is the problem is in house. I appreciate any help.
Mike
MM
M_McCallum
May 13, 2005
most of these are from 1980’s book prints that are being rescanned for pod. At this time we are over 3000 titles. It’s a big issue for us with the publisher. May have to look outside Adobe for support and a better utility as we all know the specific support for adobe is expensive and unreliable.
HD
hot_denim
May 13, 2005
Try this :

Note: Remember when you SCAN at 600DPI and Print at 600DPI they is no direct relationshop between the two in DPI (on most printers). Because printers take 1 pixel and use a sqaure grid of e.g. 16 pixels to simulate that color of that 1 pixel.

1. Scan at 600 DPI. or HIGHER e.g. 1200 is better. And ensure it is OPTICAL resolution not INTERPOLATED.

2. Use the Median filter. Adjust its controls just enought so that the gaps between the ink dots (halftone cells) on the scanned image fill to the best result.

3. Resample (using AUTO or BICUBIC interpolation) to 600 DPI. This will make the image smaller. Or anothe way a factor of 50% (if 1200DPI was the original)

4. Use the Adjust levels to Set the Highlights and blackpoints. Read the manual for more info on this section.

5. Use the UNSHARP MASK filter to sharpen. Zoom at 100% for this as this is how to correctly judge thre result. Just increases the sharpness (1st slider), leave other sliders alone.

That should make it look better.
L
LenHewitt
May 13, 2005
M_McCallum,

When printers do this they use a ‘dot for dot’ scanning method, but that is generally only available on hi-end drum scanners.

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