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Fixing scanned albums?

Aug 29, 2011, 07:49 (This post was last modified: Aug 29, 2011 07:50 by extenzer.)
Post: #1
Fixing scanned albums?
i notice when i scan the album artwork of a CD, it comes out kinda pixelated. is there a way to fix this? Like this below, i'm trying to get wallpaper/dektop quality

http://i56.tinypic.com/2nbww11.jpg
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Aug 29, 2011, 08:46
Post: #2
RE: Fixing scanned albums?
(Aug 29, 2011 07:49)extenzer Wrote:  i notice when i scan the album artwork of a CD, it comes out kinda pixelated. is there a way to fix this? Like this below, i'm trying to get wallpaper/dektop quality

http://i56.tinypic.com/2nbww11.jpg
This isn't "pixellation". These are artifacts caused by close values of the color dithering definition of the print and the sampling spatial frequency(*). Normally, scanner software can fix this at scan time (this is why scan software ask you for the kind of material (photo, prints (aka books/magazines), line art...) you are scanning. If you have no such option in your software, scan at X times the final definition, apply a Gaussian blur of X pixels, and scale down by X.

You can also try a physical blurring by scanning through tracing paper.

(*) The curious will find the explanation here: http://en.wikipedia.org/wiki/Nyquist_frequency , they just have to extrapolate to a two-dimensions signal. A regular pattern in an image (such as dithering) is a form of periodic signal.

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Aug 29, 2011, 10:45 (This post was last modified: Aug 29, 2011 11:05 by rich2005.)
Post: #3
RE: Fixing scanned albums?
@extenze


AFAIK, no easy solution especially for your image. I have an old canon lide30 scanner which being LED is prone to the same effect when scanning anything other than smooth originals.

What you can try is a fast fourier transformation (FFT) to (partially) remove the artifacts. This makes the image a bit 'soft' so then some sort of sharpening. Sharpening tends to reintroduce the artifacts so give high-pass a go.

My first stab at the problem http://i.imgur.com/UqF5u.jpg

Going to be a bit of a learning curve on your part.

For an intro into FFT see: http://www.youtube.com/watch?v=30XaCfM2QGg

For high pass sharpening there is a meet-the-gimp episode.
http://meetthegimp.org/episode-164-high-...harpening/
or a ready made at http://registry.gimp.org/node/25527

Edit: having problems with this forum timing out, must type faster
but just a thought, I have had some success in the past photographing album covers rather than scanning them.

** https://www.gimp-forum.net/ now answering questions**
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Dec 13, 2011, 22:34
Post: #4
RE: Fixing scanned albums?
This is not the "pixellation". These artifacts are defined by the color printing and sampling jitter frequency space (*) caused by the close values​​. Typically, the scanner software can fix scan time (which is why the scanning software requirements of a material (photographs, prints (also known as book / magazine), line art, ...) you are scanning.
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