# 影像處理應用之簡介

## Full text

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### 影像處理應用之簡介

2017/12/12

What is Digital image processing ?

Digital image processing(數位影像處理) is the use of

computeralgorithmsto performimage processingondigital images.

As a subcategory or field ofdigital signal processing, digital image processing has many advantages overanalog image processing. It allows a much wider range of algorithms to be applied to the input data and can avoid problems such as the build-up of noise and signal distortion during processing. Since images are defined over two dimensions (perhaps more) digital image processing may be modeled in the form ofmultidimensional systems.

-- https://en.wikipedia.org/wiki/Digital_image_processing

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Examples (Lena)

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Examples

Dilation(膨脹) ↔ Erosion(侵蝕)

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Examples

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Examples

Hough line transform 霍夫線變換

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Examples

Basic Concepts

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Basic Concepts

A colour image has 3 2-d matrices for R, G , B

Basic concepts

Example (0黑 ~ 255白)

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Basic operations

Writing images

Core module

g(x) = a f(x) + b

a = Contrast parameter b = Brightness parameter

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Core module

Contrast and Brightness example

a =2.2 b=50

Core module

Drawing functions

Lines Circles Ellipses Polygon

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Image Processing

- medianBlur - GaussianBlur - bilateralFilter

Image Processing

Smoothing

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Image Processing

Erosion and Dilation 用於減弱或突顯特徵

Erode + Dilate = Removal of stray marks

Erosion

Dilation

Image Processing

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Image Processing

Image Processing

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Image Processing

Sobel Edge Detector

Image Processing

Laplace Edge Detector

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Image Processing

Canny Edge Detector

Best edge detector available

The following 3 are considered to be keypoints in an image

1) Edges 邊緣

2) Corner 角點(also known as interest points) 3) Blobs (also known as regions of interest )

Once the features have been found, these features are

「described」.

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Feature Detection

Feature Extraction: SURF, SIFT, BRIEF

Feature Descriptors: SURF, SIFT, BRIEF, STAR Matchers: FLANN, BruteForce

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Template Matching

(圖樣比對,樣板比對,模板匹配)

Foreground Extraction(前景提取)

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Corner Detection(角點偵測, 角點檢測)

Feature Match 特徵匹配

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## How we teach computers to understand pictures

李飛飛

Image Processing v.s. Computer Vision

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Image Processing 影像處理

Computer Vision 電腦視覺

Low Level

High Level

Acquisition, representation, compression, transmission image enhancement edge/feature extraction Pattern matching image "understanding“

(Recognition, 3D)

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## References

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