How to change the pixels values along the boundary?

I have a black and white image, it has different sized white dots all along the edges. I want to change the dots along the top and bottom side of the image to black, without changing the left and right side dots of the image. Is there any way to do this?

Answer 1

[Image Analyst]

Yes. I'm assuming you have a binary (logical, black and white) image, not a grayscale image. Save the right and left columns from row 2 to the end row-1. Then write zeros into those columns. Then call imclearborder(), then write those saved columns back into the resulting image. It's only 7 lines (not including comments), but write back if you can't figure it out.