Lecture Three Chapters Two and three Photo slides

Functional Represenation of Images • Two-D function f(x, y), (x, y) pixel position. Postive

Spatial and Gray Level Resolution • Spatial resolution is the smallest level of detail

Adjacency and Connectivity • Adjacency- Two pixels p and q are adjacent if q

Chapter 3 Image Enhancement in the Spatial Domain

Adjacency , More Formally Choose a set of gray values V. If f(p) and

Chapter Three Image Enhancement in Spatial Domain Find gray level transfomration function T(r) to

Negatives Here T(r) = L-1 -r L-1 maximum gray level Produces photographic negative. Some

Mammogram Notice that the white or gray detail in the dark region is more

Log Transformation T(r) = c log(1+s) Inverse Log T(r) = exp(r/c)-1 For the next

Power Law or Gamma Transformations This the gamma correction

CRT Example CRT devices have intensity to value response functions that are power functions.

MRI of Fractured Spine Transformation is With gamma = 0. 6, 0. 4, 0.

Slides: 33

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Chapter 2: Digital Image Fundamentals

Functional Represenation of Images • Two-D function f(x, y), (x, y) pixel position. Postive and bounded • Written as f(x, y)=i(x, y)r(x, y), i(x, y) illumination from light source, r(x, y) reflectance (bounded between 0 and 1) based on material properties. E. g r(x, y)=0. 01 for black velvet, r(x, y) = 0. 93 for snow. • Intensity of monochrome image f(x, y) is synonymous with grey levels. By convention grey level are from 0 to L 1.

Chapter 2: Digital Image Fundamentals

Spatial and Gray Level Resolution • Spatial resolution is the smallest level of detail discernable in an image. Number of line pairs per millimeter, say 100 line pairs per millimeter. • Gray-level resolution is the smallest discernable change in gray level. Very subjective.

Chapter 2: Digital Image Fundamentals

Adjacency and Connectivity • Adjacency- Two pixels p and q are adjacent if q is in N(p) where N(p) is the neighborhood of p and they have closely related pixel values. Three common definitions of neighborhood are (1) 4 -adjacency. If p=(x, y), values are similar, but q is either (x-1, y), (x+1, y), (x, y-1), (x, y+1) (2) 8 -adjacency. It is possible for q to be one of the diagonal points (x-1, y-1), (x-1, y+1), (x+1, y-1), (x+1, x+1). (3) m-adjacency. Either q is 4 -adjacent to p, or q is a diagonal point and the intersection of the four neighborhood of p and that of q have no similar pixel values.