I have several pictures that I want to fix. The pictures came to me from a scanner and there is no way that job is going to be done again by the person who did it. I know for a fact that all the pictures should only have 2 colors: #ffffff and #132740. The #132740 is the background color.

But the images have many colors like this: wrong color image http://bedoya.co/wp-content/uploads/198A_85_180_3500.jpg

What I want to accomplish is something like this:

almost right colored image http://bedoya.co/wp-content/uploads/005_200_230_6000.jpg

I am using Gimp 2.8.14 for this task, thank you for any advise

  • Sorry, it looks like I can't post images on my questions – Tales Aug 11 '15 at 1:26
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    If you need to post more than two, you can just add links to the images instead – JohnB Aug 11 '15 at 3:30

IMHO you would have to convert the document in photoshop to Grayscale. Using the Curves palette, adjust the color until you get a solid black and fill the unwanted dots with a small hard paint brush. Then you add a new layer and fill with the correct blue color. Choose "difference" for that layer on the layers palette. Flatten image. Add another layer, fill with the white color and select "color" on the layers palette. Flatten the image and voila! you got your colors. There are many answers as to why the picture got this effect when scanned.

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    GIMP was the specified software but it looks like your instructions should still make sense outside of Photoshop – JohnB Aug 11 '15 at 3:10
  • Difference tool will end up filling the white with a pink color, because it will substract also the Blue #132740 From #FFFFFF, so this tool will not work. – Tales Aug 14 '15 at 1:50

First, open up the tool settings and the colors menu if you haven't already. Second, go to selection tools --> fuzzy select. Set the threshold to about 42. Hold shift and select all of the white portions of your picture. Third, click "select --> invert". Fourth, "Paint tools --> "Paintbrush", select the color you want for the background, set the opacity to 100, the size to something high, and paint the entire background blue. Lastly, select none.

  • Although this could be a nice approach to what I need, it has two downsides. The first one, the images have many little details of around 10 square pixels or less which will not be correctly selected with the fuzzy tool. The second problem is that I require to fix over 200 images and doing it that way it will be way slower, I was looking for a fast solution. – Tales Aug 11 '15 at 4:17
  • You could use color select instead, around the same threshold, but you might have to watch for the occasional speckle here or there. I thought you had four or five... so I didn't suggest color select... idk, it's still not too fast though. – Scratchifier Aug 11 '15 at 5:01

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