How to change color of edge in MATLAB?

Question

I have a script which takes an image to and applies some edge detection methods such as canny, sobel and log to it. When I run the file, a figure is drawn where the edges are white.

Is there a way to change the color of the edges to a preferred color?

function cw1
  im0 = imread('lighthouse.png');
  im = rgb2gray(im0);
  im3 = edge(im,'canny');
  im4 = edge(im, 'sobel');
  im5 = edge(im, 'log');
  im2 = my_edge1(im);
  subplot(3,2,1), subimage(im); title ('Original'); axis off
  subplot(3,2,2), subimage(im2); title ('My Edge'); axis off
  subplot(3,2,3), subimage(im3); title ('Canny'); axis off
  subplot(3,2,4), subimage(im4); title ('Sobel'); axis off
  subplot(3,2,5), subimage(im5); title ('Log'); axis off
end

Answer 1

The question is not exactly well-defined, but I'll try to help anyway. Here's a demonstration using green edges:

function q47394633
  im = rgb2gray(imread('peppers.png'));
  e = edge(im); % logical matrix, where "true" indicates an edge.
  g = reshape(uint8([0 255 0]),[1,1,3]) .* uint8(e); % Turn the above to RGB while making
  figure();                                          % only the green channel nonzero.
  subplot(3,1,1); imshow(e);    % Show white edges
  subplot(3,1,2); imshow(g);    % Show green edges
  subplot(3,1,3); imshow(im+g); % Show green edges on the image
end