Macchie, Passages and 'Edges Lost & Found'

In the visual arts, one often composes a spatially organised array of elements. These elements are often roughly uniform patches ('macchie') and edges. These are mutually complementary and often imply each other. 'Edges' may either divide or unite macchie, whereas adjacent macchie may imply an edge. Edges may be common boundaries as in cloisonnism, or be one-sided as in outline. Composition often requires that edges be 'lost', either to avoid the dreaded silhouette effect, or to merge macchie that are semantically distinct, like figure and ground. This leads to planned 'passages' or various modulations of edge quality, the 'lost & found' quality being most common. I relate such conventional artistic devices to the concept of 'edge' in image processing and human vision.