Determining Edges with a Sub-Pixel Accuracy
Step 1: Apply an edge detector (e.g., Sobel) to isolate the edges in the image.
Threshold the image leaving only the edges (i.e., areas with an
elevated sp
Image Restoration
Many image enhancement techniques are designed to compensate for the
effects of a known or estimated degradation process.
This is referred to as image restoration.
On of the most com
Edge Detection: Laplacian Operator
0 1 0
1 4 1
0 1 0
Disadvantages:
The Laplacian operator is more sensitive to impulse (salt-andpepper) noise than actual edges in the image.
The results of the L
ImageFormation
Whatistheimageirradiance,EI,asafunctionoftheobjectradiance,LO,for
agivenlensgeometry?
o Irradiance: Flux(i.e.,power)incidentonasurfaceelement
o Radiance: Fluxemittedperunitforeshortene
Image Restoration
Dr. Kaaren May
Memorial University
June 2012
Overview
What is image restoration?
Laplacian approach to restoration
Explicit modeling of blur and noise
Inverse filtering
Wiener filter
Filtering: Averaging
Assume we have access to
versions of the same image.
(
)
Calculate the average of the
(
versions on a pixel by pixel basis:
)
(
)
) consists of a gray level intensity value, (
Structural Representation of Images
The segmentation process decomposes a digital image, D,
into n subsets or regions denoted by R1, R2, , Rn.
R1 R2 . Rn = D
Ri R j = 0
for
i j
Each pixel in Ri has
Mathematical Model of Image Formation Process (Camera
Model)
Forward camera model: converts the 3D world coordinates of a point in
space to distorted pixels in a computer
The transformation describing