Chapter 8 computer vision
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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

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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


What is image processing

What is Image Processing?

Chapter 9


Application area

Application Area

Chapter 9


Image processing fields

Image Processing Fields

Chapter 9


Chapter 8 computer vision

Image Processing Fields

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 image processing fields

Digital Image Processing Fields

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

Chapter 9


2 x ray imaging

2. X-ray Imaging

Chapter 9


3 uv imaging

3. UV Imaging

Chapter 9


4 visible range

4. Visible Range

Chapter 9


4 visible range1

4. Visible Range

1964

Chapter 9


4 visible range2

4. Visible Range

Chapter 9


Chapter 8 computer vision

4. Multispectral: Visible+Infrared Bands

Chapter 9


Chapter 8 computer vision

4. Multispectral: Visible+Infrared Bands

Chapter 9


4 multispectral visible infrared bands

4. Multispectral: Visible+Infrared Bands

Chapter 9


4 multispectral visible infrared bands1

4. Multispectral: Visible+Infrared Bands

Chapter 9


Chapter 8 computer vision

5. Infrared Range

Chapter 9


6 microwave imaging radar

6. Microwave Imaging: Radar

Chapter 9


7 radio band imaging

7. Radio Band Imaging

Chapter 9


Electromagnetic spectrum

Electromagnetic Spectrum

Chapter 9


Chapter 8 computer vision

Chapter 9


Ultrasound image

Ultrasound Image

head

head

Chapter 9


Chapter 8 computer vision

Chapter 9


Chapter 8 computer vision

Chapter 9


Chapter 8 computer vision

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5

6

7

8

3

11

2

9

1

10

Steps in Digital Image Processing

Chapter 9


Chapter 8 computer vision

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Chapter 8 computer vision

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Chapter 8 computer vision

Distorted image

Restore image

3

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Chapter 8 computer vision

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Chapter 8 computer vision

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Chapter 8 computer vision

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Chapter 8 computer vision

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Knowledge base

Knowledge Base

11

Chapter 9


Chapter 8 computer vision

Image Enhancement

in the Spatial Domain


Contents1

Contents

  • Spatial Domain

  • Point Process

  • Transformation functions

  • Histogram

  • Spatial Filtering

  • Mask Operation

  • Image Enhancement

  • Smoothing Filter

Chapter 9


Spatially varying signal

Spatially Varying Signal

Chapter 9


Spatiotemporal signals

Spatiotemporal Signals

Chapter 9


Image processing

Image Processing

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

Output images

Input images

Chapter 9


Image processing1

Image Processing

  • Output pixel depends on the input image pixels

  • Usually:

Chapter 9


Chapter 8 computer vision

Transformation functions

1. contrast stretching

2. point processing : Thresholding Function

Transformation function

s= T [r]

Chapter 9


Chapter 8 computer vision

Transformation functions

Chapter 9


Chapter 8 computer vision

Transformation functions

light

dark

s

s= T [r]

r

Chapter 9

dark light


Chapter 8 computer vision

Transformation functions

original image

negative transformation

s= L-1 -r

Chapter 9


Chapter 8 computer vision

Power-Law Transformations

 = 3

 = 4

 = 5

s= cr

มืดลง

Chapter 9


Contrast stretching

Contrast Stretching

Chapter 9


Histogram

Histogram

  • Count the number of pixels with each gray level

Chapter 9


Chapter 8 computer vision

Histogram

Chapter 9


Histogram1

Histogram

Chapter 9


Chapter 8 computer vision

Chapter 9


Chapter 8 computer vision

Histogram Equalization

Chapter 9


Chapter 8 computer vision

Histogram Equalization

Chapter 9


Chapter 8 computer vision

Histogram Equalization

Chapter 9


Chapter 8 computer vision

Spatial Filtering

ค่าน้ำหนัก

ค่าPixels

Chapter 9


Laplacian output

Laplacian Output

Chapter 9


Chapter 8 computer vision

Image Enhancement

Chapter 9


Chapter 8 computer vision

Image Enhancement

Chapter 9


Chapter 8 computer vision

Image Segmentation


Line detection

Line Detection

  • 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

Chapter 9


Example1

Example

Chapter 9


Chapter 8 computer vision

link criteria:

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

Chapter 9


Chapter 8 computer vision

The End

Chapter 9


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