Consider the following black-and-white image. It depicts a freehand sketch.
I wish to characterize the "density" of sketch strokes. For e.g. the hair strokes are densely grouped together. So are strokes near the wrists and the necklace stone. Other strokes are somewhat scattered and "far", e.g. the nearly vertical strokes depicting the dress.
Is there a good measure (texture-like ?) which can be used to quantify the above notion ?