I. The existence of differences and similarities in the sur- 4. face features not only of different organisms or groups but also within given species has been demonstrated by a variety of techniques. 2. The different reactions of various organisms to the Gram stain might well be taken as one piece of evidence, the use of the electron microscop and associated prepa­rative techniques (includi...

Shadow is an inseparable aspect of all natural scenes. When there are multiple light sources or multiple reflections several different shadows may overlap at the same location and create complicated patterns. Shadows are a potentially good source of information about a scene if the shadow regions can be properly identified and segmented. However, shadow region identification and segmentation is...

We have revealed a new role for colour vision in visual scene analysis: colour vision facilitates shadow identification. Shadows are important features of the visual scene, providing information about the shape, depth, and movement of objects. To be useful for perception, however, shadows must be distinguished from other types of luminance variation, principally the variation in object reflecta...