2

I'm going slightly mad trying to 'restore' 19th-century maps that were photographed in less-than-ideal lighting conditions. Even before getting to the stain/tear repair, I have to ensure that I have an even paper base to work from, but I can't seem to make it past this point without losing a massive amount of detail.

This is the document as photographed:

Screenshot of image 'as is' from web archive

If anyone has any pointers on how to go about this, thank you very much.

Link to the full-resolution document: https://drive.google.com/open?id=0B_LmFeEi93k8OThaM1lVQlI3bzA

  • 1
    Would this not bet better asked in the Photography stack? – Digital Lightcraft Jul 31 '17 at 12:21
  • Not sure I understand what you're after. You want the paper to just be plain white even across or what? – Ryan Jul 31 '17 at 12:41
  • 1
    The included photo is a low resolution high compress JPG. It's nearly (but not fully) useless for recreating the document because all fine prints must be guessed or digged out from other sources. If you have a high resolution version without JPG artefacts, upload it to some file cloud and rewrite the question with a link to the high resolution version. If there's no hires version available and reshots are impossible, your only possiblity is to redraw the document. The curvature of the paper is possible to compensate after one guesses the right amount needed. – user287001 Jul 31 '17 at 12:45
  • I provided a link to the larger document... there are artefacts, but they are not that visible at full resolution as the image is quite large. Thanks. – Josef M. Schomburg Jul 31 '17 at 14:19
  • Yes, I would like the paper to be more-or-less white... flat, at least, and evenly lit. That's the goal, anyway... the actual 'reparation' work I have no problem with. – Josef M. Schomburg Jul 31 '17 at 14:21
1

Again an old question needs something says the system. Here it is:

Obviously the questioner has a big pile of bad photos that need some treatment. The texts are quite sharp, but the light and the paper surface color are so uneven that adding contrast does not make texts more readable.

I think that the whole process should be started by white balance correction. Everything seems to have a brown tint which probably comes from the light. After white balance correction the text page can be whitened:

enter image description here

This does not delete details as you see in a zoomed snippet:

enter image description here

The whitening is made by dividing two filtered versions of the text page:

On the bottom there is a blurred wersion which is made with the smart blur filter. Smart blur has a treshold setting for local contrast level which will stay unblurred. It can be set to keep the texts sharp, but to smooth large area variations.

On the top there's a Gaussian blurred version. All fine details are lost, only large area variations are left. The blending mode Divide makes white all which is equal in both layers.

One can add contrast by adding a curves layer and finding a curve that makes the text more black, but does not boost the underlying light random texture. It's not applied here, but we'll use it later.

The whitening removes uneven light. Unfortunately it also removes large colored areas, so color image pages should be whitened only to extract the texts and line drawings. We'll do it, too, later.

If one wants to save the colors and still add the contrast he can put a curves layer onto the smart blurred image:

enter image description here

The result is cleaner than which can be got by applying the curves layer directly to the original or white balanced version. This is because smart blur removes plenty of small noise-like fake detail.

The used blur radius here = 25 pixels. Smart blur had treshold = 10. Increasing it to 14 or 15 was possible, but the weakest printed lines started to suffer.

La Grande Finale: We can take the color from a layer that has got smart blur and more contrast. We give the color to a little greyed whitened layer that has got contrast boost. Blending mode color gives the color to the underlying image. We have also a dedicated Hue&saturation adjustment layer. It's used to desaturate selectively the orange...green fake.looking tint which exists here and there:

enter image description here

The following shot has two snippets of the result to show the remaining readability:

enter image description here

I didn't found a way to make it better except randomly by accident. I did some tests in LAB color mode. There tweaking the curves in the channels gave results of the same type + plenty of unusable crap, too. Getting some benefit manageably needs more undehood knowledge of the color math than I have, so I leave it to mode advanced users.

0

Josef, the short answer is: there is no one button to do this in Photoshop. The good news is there are several tools in PSD, used in the right combination can achieve what you asked. For example, I was able to get this much done in a few minutes using a combination of Levels, Curves, Dodge/Burn Tool, but MOSTLY used the Adjustments > Replace Color. My favorite trick in the Replaced Color is to select the background, crank up the threshold, and lighten the (background) colors.

Again - this is just a few minutes of work. With a high resolution and more time, this could be a fun project.

Too bad we're not allowed to promote our freelance services on this site ; )

enter image description here

  • I'm not looking for any 'button', but I've got 160 of these (four photos on average per 'feuille' to do ; P). I too, tried the route you suggest... but as you can see in your result, there's way too much data loss there. The best I could come up with was multiple level correction layers combined with a selective colour mask on each... and cranking the contrast on the overall pixels remaining. Thanks for your answer. – Josef M. Schomburg Jul 31 '17 at 13:55
  • Wow! That is a lot of work. With 160 unique images, this will be cumbersome (even with Photoshop Batch Actions). GL. – jhurley Jul 31 '17 at 16:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.