Archiving docs

From: Van Burnham <van_at_wired.com>
Date: Wed Apr 1 13:56:32 1998

Shawn,

If you were using Fotolook 2+ scanning software for the Arcus you possibly
engaged the "descreen" function (set to the correct line screen) which
automatically adjusts the scanner to compensate for screen angles and
minimizes moir?...however it is possible to adjust a moir?ed or "color
screened" image within Photoplop through a number of methods...depending on
the quality of the image, mode and detail...to achieve the best possible
result.

One of the easiest methods is Noise>Despeckle...this will usually do a fair
job but is usually best used in correcting badly compressed jpegs and
indexed gifs...it tends to leave ugly fragmented color boundaries and can
create that oh-so-stylish "plasticised" look we all aspire to...(joking.)
You can also try re-interpolating the image by setting your interpolation
to Bicubic, changing your image size to 200% (resampled) and then reducing
back to it's original size...this only works if maintaining sharpness is
not a factor and can sometimes exacerbate the problem. Also, Noise>Dust &
Scratches or a mild Blur>Gaussian Blur of 1 pxl or so will usually do the
trick but again, you are going to lose detail (running an unsharp mask of
30-50% can help)...

It is _always_ best to correct these problems at the scanning stage...that
is the only way to both maintain quality AND optimize
sharpness/detail...quick fixes will almost always degrade the image.


Not to ba a prude...but what on earth does this have to do with the
discussion regarding the collecting of classic computers? Archiving?
Hmmm... Most manuals are photocopied so scanning as hi-res line art is
definitely best (aliasing just seems to make text un-readable) but for
color brochures and whatnot I would definitely scan with the descreen set
to "Art Magazine (175 lpi)" with "Sharpness" set to LOW...if that looks
wonky, try "Magazine (133 lpi)." With the image in Photoshop, adjust your
curves to improve contrast and saturation (most scans of printed matter
come out FLAT FLAT FLAT) and then run an unsharp mask. Voila. This should
really get the groove on...

van




>BTW do any of you know of software that can do a good job converting color
>screened images (like out of a newspaper or magazine) back to smooth color? I
>have a theory that it's possible to extract more information than just one
>pixel per screen dot, but I'm not quite sure. I used a high-end Arcus scanner
>on a Mac once that did a beautiful job of this, but I don't know whether the
>scanner or the software was really doing the work, and whether it did
>something tricky to increase the resolution or just computed the color for the
>area occupied by each screen dot and then interpolated.
>--
> _______ KB7PWD _at_ KC7Y.AZ.US.NOAM ecloud_at_bigfoot.com
> (_ | |_) Shawn T. Rutledge http://www.bigfoot.com/~ecloud
> __) | | \_____________________________________________________________


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Received on Wed Apr 01 1998 - 13:56:32 BST

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