I prefer to design my figures externally such that I only need to include one image in latex, even if it consist in several subfigures. Say, I want to have two figures (a) and (b) side by side. Instead of creating two images (corresponding to (a) and (b)) and including both in the figure environement, I rather create one image with both figures side by side and include only this one in the figure environement.
However, I sometimes did proceed the other way round and came to appreciate the handiness of the subfig package that, together with cleveref, allows direct and automated referencing of subfigures.
Still, I want to stick to my habit of creating one image rather than two, because I can more easily adjust the position of the subfigures. Is there a way to reference a subfigure that is not explicitely defined as such in latex (because it is defined externally)?
I know that I could do this by hand with using \ref and putting an "a" or "b" behind. However, I don't know yet, if I want to have my references in parenthesis or not and this can be easily adjusted by the cleveref package at the end. Therefore, I want to keep it as homogeneous as possible.
I am sorry if there is already such a question, but I have absolutely no idea how to search for this. Using my title in the search field does give any clue.

subfigureenvironment from the excellentsubcaptionpackage. You can then globally change all of your captions easily, and easily use thecleverrefpackage too. – cmhughes Jun 04 '12 at 21:11subcaptionpackage allows labeling build-in subfigures, see http://tex.stackexchange.com/questions/40508/redefine-figref-so-that-it-can-accept-optional-arguments – Jun 05 '12 at 06:11