Question

Is there an efficient way to fill in pixels with a value of zero between pixels with non-zero values with the nearest non-zero value, while leaving the rest of pixels at zero untouched?

To clarify, I am looking to inpaint those pixels whose closest distance to a non-zero pixel is lower than a given value (e.g. 4 pixels).

The image is initially represented as a matrix of uint32 integers.

                                                      

In the example above, all the thin cracks between the colored regions should be filled with the surrounding color, while large black regions should remain the same (i.e. the routine should inpaint the pixels between the colored regions).

I imagine there is a way to do this via interpolation. In either case, I am looking for a relatively efficient solution.

Answer 1

Given an input matrix A:

b = imclose(A==0,ones(3,3)) %only the big zero regions
c = imdilate(A,ones(3,3)) %inpainting all neighboring pixels
d = zeros(size(A));
d(b==0) = c(b==0); %copy the inpainting only in places where there are no big regions

I haven’t tested it, so there may be some problems with the code. (if you made changes to the code to make it work please edit my answer)