Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Point Operations Histogram Processing, Lecture notes of Digital Image Processing

This documents is a lecture which deals with various pixels opertions

Typology: Lecture notes

2019/2020

Uploaded on 03/03/2020

zahyung-v-lover
zahyung-v-lover 🇮🇶

5

(1)

4 documents

1 / 91

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
BBM 413
Fundamentals of
Image Processing
Erkut Erdem
Dept. of Computer Engineering
Hacettepe University
Point Operations
Histogram Processing
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14
pf15
pf16
pf17
pf18
pf19
pf1a
pf1b
pf1c
pf1d
pf1e
pf1f
pf20
pf21
pf22
pf23
pf24
pf25
pf26
pf27
pf28
pf29
pf2a
pf2b
pf2c
pf2d
pf2e
pf2f
pf30
pf31
pf32
pf33
pf34
pf35
pf36
pf37
pf38
pf39
pf3a
pf3b
pf3c
pf3d
pf3e
pf3f
pf40
pf41
pf42
pf43
pf44
pf45
pf46
pf47
pf48
pf49
pf4a
pf4b
pf4c
pf4d
pf4e
pf4f
pf50
pf51
pf52
pf53
pf54
pf55
pf56
pf57
pf58
pf59
pf5a
pf5b

Partial preview of the text

Download Point Operations Histogram Processing and more Lecture notes Digital Image Processing in PDF only on Docsity!

BBM 413

Fundamentals of

Image Processing

Erkut Erdem Dept. of Computer Engineering Hacettepe University

Point Operations

Histogram Processing

Today’s topics

  • Point operations
  • Histogram processing

Digital images

  • Sample the 2D space on a regular grid
  • Quantize each sample (round to nearest integer)
  • Image thus represented as a matrix of integer values. Slide credit: K. Grauman, S. Seitz 2D 1D

Image Transformations

  • g (x,y)= T [ f (x,y)] g (x,y): output image f (x,y): input image M: transformation function
    1. Point operations: operations on single pixels
    2. Spatial filtering: operations considering pixel neighborhoods
    3. Global methods: operations considering whole image

Image Transformations

  • g (x,y)= M [ f (x,y)] g (x,y): output image f (x,y): input image M: transformation function
    1. Point operations: operations on single pixels
    2. Spatial filtering: operations considering pixel neighborhoods
    3. Global methods: operations considering whole image g ( x , y ) = M ({ f ( i , j ) |( i , jN ( x , y )})

Point operations

  • Smallest possible neighborhood is of size 1x
  • Process each point independently of the others
  • Output image g depends only on the value of f at a single point (x,y)
  • Map each pixel’s value to a new value
  • Transformation function T remaps the sample’s value: s = T(r) where
  • r is the value at the point in question
  • s is the new value in the processed result
  • T is a intensity transformation function

Sample intensity transformation

functions

  • Image negatives
  • Log transformations
    • Compresses the dynamic range of images
  • Power-law
transformations
  • Gamma correction

Sample intensity transformation

functions

  • Image negatives
  • Log transformations
    • Compresses the dynamic range of images
  • Power-law
transformations
  • Gamma correction

Point Processing Examples

produces an image of higher contrast than the original by darkening the intensity levels below k and brightening intensities above k produces a binary (two-intensity level) image

Point Processing Examples

produces an image of higher contrast than the original by darkening the intensity levels below k and brightening intensities above k produces a binary (two-intensity level) image

Changing the image mean

Slide credit: Y. Hel-Or

Image Mean

v M(v) 255 255 M ( v ) = 255 - v Slide credit: Y. Hel-Or

Image Negative

Point Operations:

Contrast stretching and Thresholding

  • Contrast stretching: produces an image of higher contrast than the original
  • Thresholding: produces a binary (two-intensity level) image

Point Operations:

Contrast stretching and Thresholding

  • Contrast stretching: produces an image of higher contrast than the original
  • Thresholding: produces a binary (two-intensity level) image

Point Operations

  • How we can process the image so that it has a better visual quality?
  • Answer is contrast stretching!

Point Operations

  • Let us devise an appropriate point operation.
  • Shift all values so that the observable pixel range starts at 0.