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I have this scan of a manuscript (c. 1780) which also includes an important signature I need to extract/isolate.

enter image description here

However a deeper look at the image shows that the grey background is actually a complex canvas-effect/pattern.

How would I extract the text, without losing any pixels of the handwriting so I can improve it later on.

What’s the best approach/technique.

Edit: For those asking, I cannot seem to obtain the original document. The manuscript was published in a book in the late 20 century, this seems the main cause for the background affect.

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    Hi. Welcome to GDSE. That's a weird effect for a scan. Was the scanner not functioning properly? It could even be a scan of a half-tone dot pattern. Can't you get hold of the original and rescan it? To be honest, it's going to be problematic no matter what you do. Maybe a levels or curves adjustment will get rid of most of it. Other possibilities for removing a regular texture pattern involve doing a fourier transform. Tutorial here. – Billy Kerr Aug 14 '20 at 13:17
  • That is not a pattern in the paper. This has been scanned not from the original but from a printed copy – the pattern you see is the grayscale printer's dots. – Jongware Aug 14 '20 at 13:34
  • @usr2564301 - it's also possible that it's a photograph of the original and the texture is on the surface of the photo paper. Old B&W photos often had this kind of canvas-like texture. It's a common problem when scanning old photographs for retouching. The Fourier Transform tutorial I linked to can eliminate such textures, it can also be used for removing halftone dots in scans of prints. – Billy Kerr Aug 14 '20 at 13:50
  • Removing the pattern without destroying the writing can be done with advanced filterings which can be found in the free G'MIC filter collection for freeware GIMP, Krita and Paint.NET. The backside ghost is the real problem. Is it in the image or can you reduce it by scanning with deep black background? – user287001 Aug 14 '20 at 14:22
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The texture is problematic. On closer inspection it looks like scan of a B&W photographic print rather than a scan of the original. Old B&W photos often had a canvas like texture which was actually embossed onto the surface of the photographic paper, and it's a problem I've often encountered when scanning old photos for retouching.

Anyway, here's how I would attempt a fix, but it requires some manual work.

  1. Use an FFT filter to remove the pattern see Photoshop tutorial here. You will have to find a filter to use with Photoshop, as it doesn't come with one as standard. If you can't find one, the free G'MIC plugin for GIMP has an FFT (Fourier Transform) and also a Bandpass filter, which is actually what I used for the example below. But it's basically the same process in GIMP or Photoshop.

  2. Do a levels adjustment to remove the grey paper background

  3. Manually retouch any leftover specks and smudges.

Here's a screenshot of G'MIC's Bandpass filter which is the one I used to remove the texture. It's really quite good for removing a very regular pattern.

enter image description here

And here's the Before and after result after doing a levels adjustment and some manual retouching. I am sure you could spend more time retouching for a better result.

enter image description here

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Unfortunately, with that background pattern from the old paper, I don't think you're going to be able to get it completely clean without some manual deleting. However, if you use the Curves adjustment you can get it much cleaner before you do manual.

Open the Curves dialog:

Open Curves Dialog

Once in there, you can click on the far left or far right of the graph and move the max point for the 0% and 100% to darken the dark areas and blow out some of the the lighter areas to white:

Curves Dialog

This is what I got from just a quick adjustment on your image:

sample image

If you play with the curve a bit, maybe grabbing a few points in the middle of the line you should be able to clean up the majority of the background, and then have to come back and manually erase the little dots that are left.

Otherwise, play with your scanner settings and see if you can get the scanner to do some of this for you. Without knowing what scanner / scan software / setting options, I can't really tell you what to change.

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