Author Topic: PI for document enhancement?  (Read 168 times)

Offline RichInLesta

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PI for document enhancement?
« on: 2018 December 31 09:56:35 »
The topic is off-topic, however it's a PI process question, so I believe this would be the best place to post this off-the-wall request....

I've been tinkering with using Pixelmath to enhance old, faded, digital copies of geneological documents.  I'm also working in Photoshop to accomplish the same, but am wondering if/how I could use Pixelmath to create greater contrast in a document, and perhaps smooth out some pixelation that occurs while blowing up the image.

Specifically, I can increase the exposure and contrast in Photoshop to make the text stand out more, but that also raises the background from white to spotchy grey.  It's this background that I'd like to be able to remove.  Hypothetically, if I could use pixelmath to turn each pixel that's below a certain value ("color") to pure white, that would/should be able to improve the contrast further.

Any thoughts?  They would certainly be very much appreciated.

Offline pfile

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Re: PI for document enhancement?
« Reply #1 on: 2018 December 31 10:05:00 »
iif ($T < 0.01, 0, $T)

change 0.01 to the threshold you want...

if you need to do it by channel you can uncheck the box for "use a single RGB/K expression" and put in 3 formulae, each with a different threshold.

rob


Offline Denjnie

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