3 Replies Latest reply on May 5, 2017 12:25 PM by pdmlynek

    How to subtract image of reverse side from obverse side of a semitransparent paper document?

    pdmlynek

      Dear experts—

       

      I have searched unsuccessfully various help sites regarding the following problem but came up empty.  Because it is a common problem, I would think that someone has successfully addressed it. (I am a newbie to Photoshop, so please forgive my lack of using proper terminology in the following query.)

       

      I, like many others who do genealogy as a hobby, am often faced with several problems when viewing images of documents that are of poor quality. One problem is caused by the diffusion of the ink on the surface of the paper.  This problem is generally solvable by photoimaging software to sharpen up the script so that is legible.  Such techniques are described in various forums, including here.  See, for example, https://forums.adobe.com/message/5599291#5599291  . My question is about a different problem.

       

      My question is about the problem that readers face when viewing images of paper documents that are written on both sides of the paper, but the paper is not fully opaque.  The image on the reverse side of the paper (verso) is partially seen on the obverse side of the paper (recto), making it the obverse side hard to read.  See, for example:

      https://www.facebook.com/photo.php?fbid=10155166482825102&set=gm.10155818242107119&type=3& theater ,

       

      Assuming that (a) better images of the document are not available, and (b) images of both the obverse and reverse are available, is there a routine method of somehow partially subtracting the image on the reverse side from the image on the obverse side?  The problem is complicated by the fact that the image on the reverse side is not clean, but obviously also shows the bleed-though from the obverse side as well.  Has anyone heard of a method of solving this problem?  I haven't seen it, but logically I would think that such a method exists.

       

      Thank you in advance!

       

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        • 1. Re: How to subtract image of reverse side from obverse side of a semitransparent paper document?
          mikeengles Level 1

          Hello

          You might be able to do something with either the levels tool or threshold

          MDE

          • 2. Re: How to subtract image of reverse side from obverse side of a semitransparent paper document?
            jay fresno Level 2

            Photoshop is magical in many ways, but there are limitations. To remove the writing on the reverse side, you would need to select it somehow. Photoshop let's you select by area or by contrast. Neither of these would work well on your image because there is very little contrast between what you want to remove and what you want to keep, and the area you want to remove is not isolated, it is throughout the whole image. That is why you've not seen a solution posted.

             

            If the ink on the reverse side of the paper is not bleeding through to the other side, you could try putting a dark paper, black or dark brown, on top of the sheet that you are scanning. That will prevent light from coming through the top of the paper.

             

            If the ink is bleeding through to the other side, the only thing that might hellp you is that the bleed through is somewhat lighter than the writing  you want to keep. You could try this:

            Add a new layer underneath the image and fill with the paper color. Since the paper is not uniform color throughout, you could select a lighter and darker paper color as your foreground/background colors and run Filter > Render > Clouds to give the layer a little variation.

            Back on the original layer, make a selection of the color you want to remove. Below I made a selection and tried not to include the darker brown that you want to keep.

            Then I chose Select > Similar, and Select > Inverse, and clicked the layer mask icon at the bottom of the layers panel.

            I ended up with this:

            Next step would be to paint with black in the mask to hide any residual writing from the reverse side.

            • 3. Re: How to subtract image of reverse side from obverse side of a semitransparent paper document?
              pdmlynek Level 1

              Thanks, MDE. 

               

              Would you use the levels tool or threshold on the image of the obverse side of the paper or on the image of the reverse side of the paper, or both images?