Fill area between two connected components in MATLAB

Question

I have a binary image that represents a number in MATLAB:

I\'d like to fill all the d

Answer 1

Assuming the top-left pixel is always outside the regions to filled:

Work across the top line, copying pixels to the output image

When you come to a white pixel followed by a black pixel in the input image, start setting white pixels in the output image, until you come to black pixel followed by a white pixel.