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Jawaharlal nehru technological university anantapur college of engineering
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**Computer Science Engineering**Offline Downloads:
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LECTURE NOTES ON
DIGITAL IMAGE PROCESSING

► What is Digital Image Processing?
Digital Image
Image is a representation, likeness, or imitation of an object or thing
Common Digital image formats include: Binary images or single bit images,
Gray scale images, Color images
A digital image is a representation of a two-dimensional image as a finite set of
digital values, called picture elements or pixels. Pixel values typically represent
gray levels, colours, heights, opacities etc. Pixels are the elements of a digital
image
— a two-dimensional function f (x,y),
The amplitude of f is called intensity or
x and y are spatial coordinates.
gray level at the point (x, y)
What is meant by Digital Image Processing? Explain how digital images can
be represented?
An image may be defined as a two-dimensional function, f(x, y), where x and y are
spatial (plane) coordinates, and the amplitude OR intensity OR gray level of f at any pair
of coordinates (x, y) .
When x, y, and the amplitude values of f are all finite, discrete quantities, we call the
image a digital image. each of these has a particular location and value.
These elements are referred to as picture elements, image elements, pels, and pixels.
Pixel is the term most widely used to denote the elements of a digital imag.
The field of digital image processing refers to processing digital images by means of a
digital computer.
A color image is just three functions pasted together. We can write this as
a “vector-valued” function:
r ( x, y)
f ( x, y) g( x, y)

b( x, y)

Representing Digital Images:
Continuous image, say a film positive is a function of 2 continuous variables f (s,t)
This can be converted into a digital image by scanning;
sampling and quantization
Sample into a 2D array f(x,y), M rows and N columns, (x,y) = discrete
coordinates, x = 0, 1, 2,…, M-1 and y = 0, 1, 2…, N-1
Section of the real plane spanned by the coordinates of an image = spatial
domain x and y are called spatial variables or spatial coordinates
f (x,y) can be represented in three ways:
Image plotted as a surface, Image displayed as a visual intensity array, Numerical array

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