Imagemagick remove odd pixels from the image

Question

I have a mortar image and it has some blackish pixels on the inside edges.

I need to make those blackish pixels colored same as the gray mortar color.

Look at the beginning of the image I have pointed out some blackish pixels on the edges

Answer 1

one (time consuming) solution is to switch colors to grey of every pixel that passes the following condition:

pixel is part of a component that is connected to a mortar but is not part of the mortar rectangle, this can be achieved with modifications to "Connected-component labeling" algorithm.

one way to do this modification is:

1. scan the image one time with Connected-component labeling algorithm (with threshold to contain grey and black colors pixels).
2. discard every component that doesnt contain a mortar (in your case this can be achieved with a demand of minimum pixels in a component).
3. scan the image a second time, each fixel that is on a line with an end and is black, switch color to grey. this can be done in number of ways, one way is to search the line ends and then changes colors on all the line (you can flag the line ends in Connected-component labeling algorithm to save time).

hope this helps.