How to split a complex shape into smaller simpler shapes based on a given angle using image processing?

Good day, I would like to ask if there's any way to divide a complex (irregular) shape into smaller simpler shapes based on a given angle using image processing. For instance, consider the example below:

shape A is shown to be cut into smaller shapes by 0/180 deg (horizontally) while shape B cut by 90/270 deg (vertically).

Thank you very much and hoping for feedback.

Answer 1

[Image Analyst]

Since there is no unique way to chop up your blob, you'd have to write your own code according to your rules. The only thing built in to the Image Processing Toolbox is qtdecomp(), quadtree decomposition, which divides the picture up into squares of various sizes.

[c4mm11]

I see. Do you mind suggesting a way to start? Say, consider Shape A. I still can't figure out on how to get the regions.

Thank you very much.

[Image Analyst]

I don't know why you want to do this, but basically you're going to have to rewrite the standard connected components labeling method. You scan down row by row detecting which pixels are true and labeling them. If they're separate, assign different labels. On the next row if any row above is a different label, you'd make it the same label. But you'll have to not do that. You'll have to start a third label. Then if you have two regions again, you'll have to start with a brand new set of labels. It's not easy and too much work for me to do it for you. Good luck though.

[c4mm11]

I haven't thought of labeling it this way. Your input greatly helps! Thank you very much!

[Image Analyst]

I learned how they did it like 20 years ago when was using a program called Visilog and computers were so slow you could see it as it scanned down, assigning bright colors to each label, then it would scan again from bottom up doing the same thing, sometimes changing labels. It kept scanning up and down repeatedly until no more pixels got changed. Of course now it's so fast and normally now they won't show you the labels line-by-line as it scanned like this old Visilog program did.