Sayısal Görüntü İşleme Teknikleri
Doç. Dr. Mehmet Serdar Güzel
Slides are mainly adapted from the following course page:
http://www.comp.dit.ie/bmacnamee and
https://www.tutorialspoint.com
Lecturer
Instructor: Assoc. Prof Dr. Mehmet S Güzel
Office hours: Tuesday, 1:30-2:30pm
Open door policy – don’t hesitate to stop by!
Watch the course website
Assignments, lab tutorials, lecture notes
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What is Image Restoration?
Image restoration efforts to restore images that have been degraded
Identify the degradation process and attempt to reverse it
Similar to image enhancement, but more impartial
What is Image Restoration?
Noise Model
We can consider a noisy image to be modelled as follows:
where f(x, y) is the original image pixel, η(x, y) is the noise term and g(x, y) is the resulting noisy pixel
If we can estimate the model the noise in an image is based on this will help us to figure out how to restore the image
) ,
( )
, ( )
,
( x y f x y x y
g
Noise Models
Gaussian Rayleigh
Erlang Exponential
Uniform
Impulse
Images taken from Gonzalez & Woods, Digital Image Processing (2002) There are many different models for the image
noise term η(x, y):
Gaussian
Most common model
Rayleigh
Erlang
Exponential
Uniform
Impulse
Salt and pepper noise
Zooming Methods
Methods
Pixel replication or (Nearest neighbor interpolation)
Zero order hold method
Zooming K times
Each of the methods have their own advantages and disadvantages. We will start by discussing pixel
replication
Introduction to JPEG Compression
Image compression is the method of data compression on digital images.
The main objective in the image compression is:
Store data in an efficient form
Transmit data in an efficient form
Image compression can be lossy or lossless.
JPEG compression
How jpeg compression works
JPEG compression
How jpeg compression works