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Chapter 8 Computer Vision. Contents. What is Image Processing? Digital Image Processing Electromagnetic Spectrum Steps in Digital Image Processing. What is Image Processing?. Application Area. Image Processing Fields. Image Processing Fields. Digital Image Processing.

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Chapter 8 computer vision

Chapter 8 Computer Vision


Contents
Contents

  • What is Image Processing?

  • Digital Image Processing

  • Electromagnetic Spectrum

  • Steps in Digital Image Processing

Chapter 9



Application area
Application Area

Chapter 9




Digital image processing
Digital Image Processing

  • “Digital Image”?

    • Digital

    • Image

  • “Image Processing”?

Chapter 9


Digital image processing1
Digital Image Processing

What is a signal?

A signal is a function that maps a set (domain) to another set (range)

Chapter 9


Digital image processing2
Digital Image Processing

A signal is a function that maps a set (domain) to another set (range)

For each point in time (t), assign a voltage value (y(t)).

Domain = time interval

Range = voltage interval

Chapter 9


Digital image processing3
Digital Image Processing

  • Image

    • An image is a two-dimensional signal

A signal is called two-dimensional

if the domain is two-dimensional

Chapter 9


Digital image processing4
Digital Image Processing

  • Image

    • An image is a two-dimensional signal

Chapter 9


Digital image processing5
Digital Image Processing

  • Digital Image

    • Vs Analog image?

  • Digital vs analog signal

Chapter 9


Signal types
Signal Types

  • Domain

  • Range

    • Countable

      • Quantized Signal

Chapter 9


Digital signal
Digital Signal

  • A signal is “digital”

    • if both the domain andthe rangeare countable

    • I.e., if it is a quantized discrete-time (or -space) signal

Chapter 9


Digital image processing6
Digital Image Processing

  • Digital Image

    • A digital image is a two-dimensional signal with a countable domain and a countable range

Chapter 9


Digital image processing7
Digital Image Processing

  • Digital Image

Chapter 9


Digital signal1
Digital Signal

  • How is a digital signal formed?

    • Discrete domain

      • Domain is inherently discrete, or

      • Sample a continuous interval

    • Discrete range

      • Range is inherently discrete, or

      • Sample a continuous interval

Chapter 9


Domain and range
Domain and Range

  • Continuous-time signals

    • t and y (t) have physical meanings

  • Digital signals

    • n and y (n) do not have physical meanings and can be arbitrary

Chapter 9



Digital images 80 years ago
Digital Images: 80 years ago

1921

Range has 5 values!

1922

1929

Chapter 9


Electromagnetic spectrum em

1 2 3 4 5 6 7

Electromagnetic Spectrum : EM

Chapter 9


1 gamma ray imaging
1. Gamma-Ray Imaging 6 7

Chapter 9


2 x ray imaging
2. X-ray Imaging 6 7

Chapter 9


3 uv imaging
3. UV Imaging 6 7

Chapter 9


4 visible range
4. Visible Range 6 7

Chapter 9


4 visible range1
4. Visible Range 6 7

1964

Chapter 9


4 visible range2
4. Visible Range 6 7

Chapter 9





4 multispectral visible infrared bands1
4. Multispectral: 6 7 Visible+Infrared Bands

Chapter 9


5. Infrared Range 6 7

Chapter 9



7 radio band imaging
7. Radio Band Imaging 6 7

Chapter 9




Ultrasound image
Ultrasound Image 6 7

head

head

Chapter 9




4 6 7

5

6

7

8

3

11

2

9

1

10

Steps in Digital Image Processing

Chapter 9


1 6 7

Chapter 9


2 6 7

Chapter 9


Distorted image 6 7

Restore image

3

Chapter 9


4 6 7

Chapter 9


5 6 7

Chapter 9


6 6 7

Chapter 9


7 6 7

Chapter 9


8 6 7

Chapter 9


9 6 7

Chapter 9


9 6 7

Chapter 9


10 6 7

Chapter 9


Knowledge base
Knowledge Base 6 7

11

Chapter 9


Image Enhancement 6 7

in the Spatial Domain


Contents1
Contents 6 7

  • Spatial Domain

  • Point Process

  • Transformation functions

  • Histogram

  • Spatial Filtering

  • Mask Operation

  • Image Enhancement

  • Smoothing Filter

Chapter 9



Spatiotemporal signals
Spatiotemporal Signals 6 7

Chapter 9


Image processing
Image Processing 6 7

  • An image processing system maps an input image to an output image

Output images

Input images

Chapter 9


Image processing1
Image Processing 6 7

  • Output pixel depends on the input image pixels

  • Usually:

Chapter 9


Transformation functions 6 7

1. contrast stretching

2. point processing : Thresholding Function

Transformation function

s= T [r]

Chapter 9



Transformation functions 6 7

light

dark

s

s= T [r]

r

Chapter 9

dark light


Transformation functions 6 7

original image

negative transformation

s= L-1 -r

Chapter 9


Power-Law Transformations 6 7

 = 3

 = 4

 = 5

s= cr

มืดลง

Chapter 9


Contrast stretching
Contrast Stretching 6 7

Chapter 9


Histogram
Histogram 6 7

  • Count the number of pixels with each gray level

Chapter 9


Histogram 6 7

Chapter 9


Histogram1
Histogram 6 7

Chapter 9



Histogram Equalization 6 7

Chapter 9


Histogram Equalization 6 7

Chapter 9


Histogram Equalization 6 7

Chapter 9


Spatial Filtering 6 7

ค่าน้ำหนัก

ค่าPixels

Chapter 9


Laplacian output
Laplacian Output 6 7

Chapter 9


Image Enhancement 6 7

Chapter 9


Image Enhancement 6 7

Chapter 9



Line detection
Line Detection 6 7

  • horizontal,... +45 degree,.. vertical... and -45 degree masks

  • Horizontal mask will result with max response when a line passed through the middle row of the mask with a constant background.

  • the similar idea is used with other masks.

  • note: the preferred direction of each mask is weighted with a larger coefficient ....(i.e.,2)than other possible directions.

Chapter 9


Example
Example 6 7

Chapter 9


Example1
Example 6 7

Chapter 9


link criteria: 6 7

1). the pixels belonged to one of the set of pixels linked according to the highest count

2). no gaps were longer than 5 pixels

Chapter 9


Result of applying t
Result of applying T 6 7

Chapter 9


The End 6 7

Chapter 9


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