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DIP Lect 4

The document discusses point operations in digital image processing, highlighting their significance in image pre-processing. It covers arithmetic operations such as addition, subtraction, multiplication, division, and complementary operations, along with their effects on images. Additionally, it addresses color image operations including changing lighting colors, swapping channels, and eliminating color channels to manipulate image appearance.

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16 views22 pages

DIP Lect 4

The document discusses point operations in digital image processing, highlighting their significance in image pre-processing. It covers arithmetic operations such as addition, subtraction, multiplication, division, and complementary operations, along with their effects on images. Additionally, it addresses color image operations including changing lighting colors, swapping channels, and eliminating color channels to manipulate image appearance.

Uploaded by

ams2010sams2010s
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Digital Image Processing

Assoc. Prof. Mina Ibrahim


Lecture 4
POINT OPERATIONS
Introduction
Neighborhood processing vs. Point operations
Introduction
Although point operations are the simplest, they
contain some of the most powerful and widely used of
all image processing operations.

They are especially useful in image pre-processing,


where an image is required to be modified before the
main job is attempted.
Arithmetic operations
These operations act by applying a simple function

y = f(x)
Types of operations:
1. Addition/Subtraction

2. Multiplications/Division

3. Complementary
Addition/Subtraction
To add /subtract a constant from each pixel in the
image.
y=x±C
Addition/Subtraction
Multiplications/Division

 To multiply /divide each pixel in the image x in/by


c
constant c.
Multiplications/Division
Complementary
The complement of a grey scale image is its
photographic negative.
Complementary
Image Solarization
Complementing only part of the image.
Image Solarization

 The image recorded on a negative or on a print is


wholly or partially reversed in tone. Dark areas
appear light or light areas appear dark.
Color Images Operations
Color Images Operations

Possible channel operations:

 Changing the image lighting color.

 Swapping image channels.

 Eliminating color channels.


Changing the image lighting color
To change the intensity of one or more channel by
adding or subtracting a constant.

 R + C => the image will be reddish


 G + C => the image will be greenish
 B + C => the image will be bluish
 R,G + C => the image will be yellowish
Changing the image lighting color
Swapping image channels
To exchange the intensity between the image
channels.
 R , G => the image will be GRB

 G , B => the image will be RBG

 B , R => the image will be BGR


Other spaces could be obtained by swapping 2
channels at once like; GBR and BRG.
Swapping image channels
Eliminating color channels
To set one or more color channels by zero values.
 Eliminating R => image will be in cyan

 Eliminating G => image will be in magenta

 Eliminating B => image will be in yellow

 Eliminating R,G => image will be in blue

 Eliminating G,B => image will be in red

 Eliminating B,R => image will be in green


Eliminating color channels
Eliminating color channels

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