For object recognition, an image is segmented into areas of similar
homogeneity at a coarse scale, which are then interpreted as surfaces.
Information from different spatial scales and different image features is
simultaneously evaluated by exploiting statistical dependencies on their
joint appearance. Thereby, the local standard deviation of specific gray
levels in the close environment of an observed pixel serves as a measure
for local image homogeneity that is used to get an estimate of dominant
global object contours. This information is then used to mask the
original image. Thus, a fine-detailed edge detection is only applied to
those parts of an image where global contours exist. After that, said
edges are subject to an orientation detection. Moreover, noise and small
details can be suppressed, thereby contributing to the robustness of
object recognition.