Title: Chapter 2: Digital Image Fundamentals
1Chapter 2 Digital Image Fundamentals
2.1 Elements of visual perception 2.2 Light and
electromagnetic spectrum 2.3 Image sensing and
acquisition 2.4 Image sampling and
quantization 2.5 Some basic relationships
between pixels
22.1 Elements of Visual Perception
32.1.1 Structure of the Human Eye
- Cones highly sensitive to color, 67 million
- Rods sensitive to low levels of illumination,
75150 million - dim-light vision
42.1.2 Image Formation in the Eye
52.2 Light and Electromagnetic Spectrum
62.2 Light and Electromagnetic Spectrum
72.3 Image Sensing and Acquisition
82.3.4 A Simple Image Formation Model
2-D digital image
illumination
shift, scale
92.4 Image Sampling and Quantization
- Image acquisition generate digital images from
sensed data - Two processes sampling, quantization
- Sampling digitizing coordinate values
- Quantization digitizing amplitude values
102.4.1 Basic Concepts in Sampling and Quantization
112.4.1 Basic Concepts in Sampling and Quantization
122.4.2 Representing Digital Images
Spatial domain
Spatial coordinate (x,y) discrete quantities
(integers)
132.4.2 Representing Digital Images
142.4.2 Representing Digital Images
- MxN digital image in compact matrix form
- Each element in the matrix array
- Image element, picture element, pixel, pel
- MxN digital image in more traditional matrix
notation
ai,j f(i,j)
152.4.2 Representing Digital Images
0, L-1 dynamic range
L quantization level
- b number of bits to store digital image
if MN
162.4.2 Representing Digital Images
172.4.3 Spatial and Intensity Resolution
Spatial resolution change down-sampling
(subsampling)
182.4.3 Spatial and Intensity Resolution
Spatial resolution change up-sampling from
down-sampled images
192.4.3 Spatial and Intensity Resolution
202.4.3 Spatial and Intensity Resolution
Gray-level resolution change
256 levels (k 8)
128 levels (k 5)
false contouring
64 levels (k 6)
32 levels (k 5)
212.4.3 Spatial and Intensity Resolution
Gray-level resolution change
false contouring
8 levels (k 3)
16 levels (k 4)
2 levels (k 1)
4 levels (k 2)
222.4.4 Image Interpolation
128?1024
64?1024
32?1024
Zooming by pixel replication
Zooming by bilinear interpolation using four
neighbors
232.4.4 Image Interpolation
242.5 Some Basic Relationships Between Pixels
2.5.1 Neighbors of a Pixel
- N4(p) 4-neighbors of p, p(x,y)
- (x1, y), (x-1, y), (x,y1), (x,y-1)
- ND(p) diagonal neighbors of p, p(x,y)
- (x1, y1), (x1, y-1), (x-1,y1), (x-1,y-1)
- N8(p) union of N4(p) and ND(p)
252.5.2 Adjacency, Connectivity, Regions, and
Boundaries
- 4-adjacency Two pixels p and q are 4-adjacent
- if q is in N4(p)
- 8-adjacency Two pixels p and q are 8-adjacent
- if q is in N8(p)
262.5.3 Distance Measures
- p(x,y), q(s,t), z(v,w) pixels
Requirements for distance function (metric)
272.5.3 Distance Measures
- D4 distance (city-block distance)
- D8 distance (chessboard distance)