Image Processing Georg Fries

Georg Fries Modelling and Simulation using MATLAB

1. Introduction

Content Images in MATLAB

RGB, Grey-Scale, Binary Images and Matrices Handling Images

Intensity Transformation Adjusting Contrast and Brightness Histogram

Spatial Filtering Neighbourhood Sharpening and Softening

Denoising Speckle and Salt & Pepper Noise

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Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

Images: London Eye

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Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

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It is a Matrix!

Georg Fries Modelling and Simulation using MATLAB 5

1. Images in MATLAB

It is a Matrix!

Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

Image Types True Colour (RGB) Grey-Scale Binary

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Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

Image types True Colour (RGB) Grey-Scale Binary

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Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

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Image types Grey-Scale Grey-Scale moose_gray.png! M-by-N matrix Pixel values I(r,c)

specify intensity values of monochrome image

8 bit: uint8 0 => Black 255 => White

Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

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Image types Binary Binary moose_bin.png M-by-N matrix Containing only 0s and

1s, interpreted as Black and White

1 bit: logical 0 => Black 1 => White

Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

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Image types RGB True Colour moose.png M-by-N-by-3 array Pixel values specify

intensity values of 3 monochrome images

24 bit: uint8 x 3 0 => Black 255 => Max(R,G,B)

Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

True Colour

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RGB Red Green Blue

Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

Handling Images

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MATLAB func+on Descrip+on imshow(I)! Displays the image I in a Handle Graphics gure, where I is

a grey scale, RGB (truecolour), or binary image I = imread(filename,fmt) ! Reads a grey scale or colour image from the le "lename"

imwrite(I,filename) ! Writes image data I to the le "lename" Inferring the le format from the extension Creates the new le in your current folder

info = imfinfo(I)! Returns informaDon about an image in a graphics le

image! Creates an image graphics object by interpreDng each element in a matrix as an index into the gure's colormap or directly as RGB values, depending on the data specied

Reference: hIp://www.mathworks.com/help/matlab

Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

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Create Binary Image using im2bw Grey-Scale Binary I=imread('moose_gray.png'); threshold = 0.55;!BW = im2bw(I, threshold);!imwrite(BW,'moose_bin.png');!!! Change the threshold value!

Georg Fries Modelling and Simulation using MATLAB

1. Images in MATLAB

True Colour

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RGB Red Green Blue

RGB=imread('piccadilly.jpg');!RGB(:,:,2)=0;!RGB(:,:,3)=0;!imshow(RGB)! RGB=imread('piccadilly.jpg');!

RGB(:,:,1)=0;!RGB(:,:,3)=0;!imshow(RGB)!

RGB=imread('piccadilly.jpg');!RGB(:,:,1)=0;!RGB(:,:,2)=0;!imshow(RGB)!