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Ask HN: How would I restore this 101 year old postcard?

4 points by Waterluvian ↗ HN
How do I approach making this legible? Is there a “magical AI” solution these days? I know the basics of image processing and filtering but I can barely read my own handwriting so I suspect I’d need help from AI or someone even if I managed to isolate the signal.

P.S. I hope I’m not doxxing my great great grandfather or anything.

https://ibb.co/4gC2X1fX

https://ibb.co/7J1jf4dV

5 comments

[ 11.6 ms ] story [ 55.1 ms ] thread
thataccount
Saturation curve in photo editing software possibly broken down by channels.
gus_massa
I agree. GIMP has a tool that shows the histogram of the number of pixels with each brightness and you can add apply a curve to make the background still almost white and the ink almost black. Some random tutorial from a google search https://www.gimp.org/tutorials/community/Basic_Color_Curves/ There are a few videos https://www.google.com/search?q=Saturation+curve+gimp

[@OP: I can give it a try on Monday, if I'm very bored and you are very lucky. Take a look in a few days, but I'm not a professional so expect a crappy result if any.]

Have you tried with ChatGPT? IIRC. My wife used it to delete the writing in a test of my daughter, so she could do it again to practice for school. I guess you can ask it to enhance the contrast.

Have you tried with the CamScanner app? It's like magic, but the adds are too aggressive and try to install other apps, so only 50% recomendation.

gus_massa
@OP: I tried but failed. In the main image the bottom left corner is darker. How did you took the photo? For slightly similar tasks I like natural light from a window in a cloudy day, so it's very diffuse. I take the photo far away from the paper to avoid shadows. It's better if you have a support for the phone/camera.

   O                     w
   |    ---camera        i
   |   /                 n
   me /                  d
   |        photo        o
   |   --------------    w
   |   |  table     |            
  / \  |            |
k310
I did some fiddling in GIMP, including edge detection filters. Not much progress.

The uneven illumination might call for working with regions separately. I didn't see an option to even it out. Bright areas seem blocked/saturated (in brightness, not color)

Unlike film, digital sensors seem better at letting you bring up detail in shadows and worse with highlights, which seem blocked.

"I don't use algorithms" (separately) unless they're incorporated in GIMP. More a photographer than anything else. Few words were readable.

anenefan
I would suggest taking a photo under different lighting conditions, uv is a thought but being graphite based, IR would seem best to highlight the writing, but I could not say which would be better, same angle from beside the camera or from the side slightly above the plane of the bespoke postcard.

Oh if I'm not mistaken, postage date suggests 111 years old.

Edit about 30 min later.

A thought, might be (iron gall) ink and not pencil. UV might be useful. [1]

[1] https://aiccm.org.au/network-news/summary-ultra-violet-fluor...