Legacy ImageMagick Discussions Archive

Hello,

I have monotone images being generated outside of IM, and contain what's effectively the "ordered-dither=checks" dithering.

I've been trying to figure out a way to remove such dithering - what I'd like is to make any/all instances of such dithering fully black.

Example file is (Group 4 monochrome tiff):

https://drive.google.com/open?id=1hLP9h ... rjohtvWF82

And here is the up-close zoom of the dithering:

https://drive.google.com/open?id=1KqdK1 ... rECwvxYoV4

https://drive.google.com/open?id=14CBgt ... tyU-91jdNP

https://drive.google.com/open?id=1IGtFX ... 0vLY8hqMZ0


Ultimately, where dithering exists, I'd like to make it black. In the third close-up, I'd want to make it black up until there is a solid area of white.

I've been trying to leverage morphology to accomplish, but not having much luck. Any input or thoughts is greatly appreciated.

One potential way is notch filtering via FFT processing. See http://www.fmwconcepts.com/imagemagick/ ... se_removal

Another way, might be to simply create a mask image that is black where the checkerboard does not exist and white where it does. Then use the mask to replace the checkerboard with a black image by 3 image compositing. See https://imagemagick.org/Usage/compose/#compose

How about (Windows syntax):

Oh wow - perfect - thank you! I had not looked into FFT - but have definitely reviewed everything I could find you've written re Morphology. I had actually explored HMT for a bit to deal with something way earlier in the process, but ultimately took a different approach and forgot about it.

This is great - thank you so much!