How to change the thickness of lines in imagesc plot?

I plotted this figure using command

imagesc(fd,f,log10(P));

I am able to change the colors of the figure, but I can't control the thickness of the line in Figure. I would like to draw the same figure with thicker and black colored line.

How could I proceed? Thanks.

Answer 1

[Image Analyst]

I don't know where the lines came from but if they are burned into the image, you can widen dark things by using imerode() which is a local minimum:

se = strel('disk', 4, 0);
fd = imerode(fd, se);