Some algorithsm work by creating a first corse-graiend or approximate result, and then gradually creatting more detail. This can be especially useful in image processing. For example Marr's primal sketch using Laplacian-of-Gaussian filter to initially look for objects and intereting parts of an image at low resolution, and then focuses mroedetiled processing on the araes of interest.
Used in Chap. 12: page 170