21-05-2012, 03:56 PM
IMAGE COMPRESSION using FRACTIONAL FOURIER
TRANSFORM
[attachment=22602]
Introduction
Now a days, the usage of digital image in various applications is growing rapidly.
Video and television transmission is becoming digital and more and more digital
image sequences are used in multimedia applications.
A digital image is composed of pixels, which can be thought of as small dots on
the screen and it becomes more complex when the pixels are colored. An enormous
amount of data is produced when a two dimensional light intensity function is sam-
pled and quantized to create a digital image. In fact, the amount of data generated
may be so great that it results in impractical storage, processing and communica-
tions requirements .
Fundamentals of Digital Image
An image is a visual representation of an object or group of objects. When using
digital equipment to capture, store, modify and view photographic images, they must
rst be converted to a set of numbers in a process called digitization or scanning.
Computers are very good at storing and manipulating numbers, so once the image
has been digitized it can be used to archive, examine, alter, display, transmit, or
print photographs in an incredible variety of ways. Each pixel of the digital image
represents the color (or gray level for black white images) at a single point in the
image, so a pixel is like a tiny dot of a particular color. By measuring the color of
an image at a large number of points, we can create a digital approximation of the
image from which a copy of the original image can be reconstructed. Pixels are a
little grain like particles in a conventional photographic image, but arranged in a
regular pattern of rows and columns [1,2]. A digital image is a rectangular array of
pixels sometimes called a bitmap. It is represented by an array of N rows and M
columns and usually N=M. Typically values of N and M are 128, 256, 512 and 1024
etc.
Types of Digital Image
For photographic purposes, there are two important types of digital images: color
and black white. Color images are made up of colored pixels while black white
images are made of pixels in di erent shades of gray.
Black White Images
A black white image is made up of pixels, each of which holds a single number
corresponding to the gray level of the image at a particular location. These gray
levels span the full range from black to white in a series of very ne steps, normally
256 di erent grays . Assuming 256 gray levels, each black and white pixel can be
stored in a single byte (8 bits) of memory.
Color Images
A color image is made up of pixels, each of which holds three numbers corresponding
to the red, green and blue levels of the image at a particular location. Assuming 256
levels, each color pixel can be stored in three bytes (24 bits) of memory. Note that
for images of the same size, a black white version will use three times less memory
than a color version.
TRANSFORM
[attachment=22602]
Introduction
Now a days, the usage of digital image in various applications is growing rapidly.
Video and television transmission is becoming digital and more and more digital
image sequences are used in multimedia applications.
A digital image is composed of pixels, which can be thought of as small dots on
the screen and it becomes more complex when the pixels are colored. An enormous
amount of data is produced when a two dimensional light intensity function is sam-
pled and quantized to create a digital image. In fact, the amount of data generated
may be so great that it results in impractical storage, processing and communica-
tions requirements .
Fundamentals of Digital Image
An image is a visual representation of an object or group of objects. When using
digital equipment to capture, store, modify and view photographic images, they must
rst be converted to a set of numbers in a process called digitization or scanning.
Computers are very good at storing and manipulating numbers, so once the image
has been digitized it can be used to archive, examine, alter, display, transmit, or
print photographs in an incredible variety of ways. Each pixel of the digital image
represents the color (or gray level for black white images) at a single point in the
image, so a pixel is like a tiny dot of a particular color. By measuring the color of
an image at a large number of points, we can create a digital approximation of the
image from which a copy of the original image can be reconstructed. Pixels are a
little grain like particles in a conventional photographic image, but arranged in a
regular pattern of rows and columns [1,2]. A digital image is a rectangular array of
pixels sometimes called a bitmap. It is represented by an array of N rows and M
columns and usually N=M. Typically values of N and M are 128, 256, 512 and 1024
etc.
Types of Digital Image
For photographic purposes, there are two important types of digital images: color
and black white. Color images are made up of colored pixels while black white
images are made of pixels in di erent shades of gray.
Black White Images
A black white image is made up of pixels, each of which holds a single number
corresponding to the gray level of the image at a particular location. These gray
levels span the full range from black to white in a series of very ne steps, normally
256 di erent grays . Assuming 256 gray levels, each black and white pixel can be
stored in a single byte (8 bits) of memory.
Color Images
A color image is made up of pixels, each of which holds three numbers corresponding
to the red, green and blue levels of the image at a particular location. Assuming 256
levels, each color pixel can be stored in three bytes (24 bits) of memory. Note that
for images of the same size, a black white version will use three times less memory
than a color version.