Digital Image Processing - Chapter 5: Feature Extraction - Nguyen Viet Dung

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1) We postulate that perceptually important features occur wherever the surface

normal vector n(r) is nearly perpendicular to the camera viewing direction

v(r), that is, at points having position vector r where 0

and is a small positive number.

2) We assume that the camera and the light source are located far away from

the scene, the object surface has Lambertian surface reflectance for which light is reflected equally in all directions, and source illumination comes from the camera direction. Then the image I(x,y) is given by