I have a single .png file that contains 4 figures (images) uniformly located on it. I would like to have a subfigure letter for each of them ( (a),(b),(c),(d) ), but I would like to avoid manually separating the figure in 4.
Is there a way to include a line below a single figure with (a),(b),(c),(d) between the figure and the caption? Best possible case by choosing the location of these letters so I can adjust them as pleased.

trimandclipthe PNG to extract out the four images. Is this what you mention you are not interested in? – Werner Jan 26 '17 at 17:11