I had to replace certain sensitive data in photocopied document in order to who these to the public. There are popular photocopy filters, including for gimp, but these are geared to images, not for text. Here are what I did to achieve good enough result so now I can show the data to different audiences. It is probably easy to show that part of it is cheated but that is not the problem here. The process is mostly the same for Gimp 2.8 and 2.10, just the pixelize pixel size calculation seem to differ.

Lets take this unpleasant text as the point of departure:

It’s dimension is 417x93 pixels.

  1. Figure out the right font and fontsize. The font size may differ quite a bit from the one used in the original document as this is a function of both original size and scan density. In this example case 39 points works well. You can compare the height of “l” and other similar letters. Note that FreeSerif fonts are quite close to Times New Roman.
  2. Write the text with text tool. It allows you to correct it later but it’s a bit cumbersome. I’d do it somewhere on the white background, just to see if everything is right.

  3. Move the just created text layer in the correct place, over the original text. In this way you can easily see if the size is correct, and fine-adjust it’s placement:

  4. Delete the original text from underneath the new one. The best way to do this is to select the original image layer and operate there.
  5. As the filters do not work well on text layer, you have to flatten the image. Converting text layers to ordinary layers will probably do too but I did not investigate this option much. Use the menu: Image -> Flatten image. The visible result does not change.
    Now select the new text in the image and apply all the following filters on this:
  6. Add a little bit of pick noise (I used 5%) to make the otherwise identical letters slightly different. It is in Filters -> Noise -> pick. Pick swaps around colors of neighboring pixels, in my experience 5-10% pick is a good choice:
  7. Next, pixelize the text: Filters -> blur -> pixelize. The suitable pixel size depends on how large are the pixels in your original text, I used 3 points in gimp 2.8 and 2 points in gimp 2.10:
  8. Apply threshold to transform the intermittent grays into black and white: Colors -> threshold. This is the most important step that very much determines how will your final text look like. Play with the threshold value to achieve a result that is sufficiently dark but not too dark. I used the threshold value 167:
  9. Finally, add some more pick noise, in order to simulate some small-scale randomness: Filters -> Noise -> pick. I used 5% amount, this looks about right:

This text looks a lot more pleasant than the original one, right?