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ABSTRACT:-

            To
transfer the image in many types are used this such as computer, mobile and
internet etc. The transmission of images in computer, mobile and internet are
etc. To store an image digital data are required in large quantities. To
overcome the problem limited bandwidth, there is need to compress the image
before transmission. To make clear the problem various image compression
techniques have been developed in digital image processing.   This study presents a survey on   Image Compression Techniques.

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Keywords:
Compression, image compression, lossy compression, lossless compression.

 

INTRODUCTION:-

Digital
images become popular for transferring visual information which is using the images
over traditional camera film images. It produces instant images, which can be
viewed as film processing. But these images are displayed in large size. To
overcome the problem use of image compression technique is used to reduce to
size without affecting the quality of image.

 

 

 

The
reduction performed to store the more images in the disk or given memory space.

To
reduce the size required a bandwidth less and quickly to transfer the image or
less time transfer the image related to cost.

The
compression techniques are classified in two. One is lossless compression and
another one is lossy compression.

 

COMPRESSION
TECHNIQUES:-

The
set of compression techniques used in image processing are for various
applications.

·        
Lossless Compression

·        
Lossy Compression

Lossless Compression:-

              Lossless compression perform in original
image can be perfectly recovered from the compression image which is provide a
quality of image. It is also known as entropy coding since to eliminate the
redundancy use decomposition technique. These are mainly used for application
like medical imaging, technical drawing etc. Some of the methods using lossless
compression technique.

Ø  Huffman
Coding

Ø  Area
Coding

Ø  Arithmetic
Coding

Ø  Run
Length Coding

 

HUFFMAN CODING:-

             Huffman coding based occurs on the
frequency and probabilities. The frequency occurs on the file. To reduce the
file size by 10% to 50% for Huffman coding and irrelevant information can be
removed.                                                                                                                                                 

 Each pixel is treated as a symbol. The symbols
are representing a higher frequency which is assigned a smaller number of bits which
the symbol less frequency is assigned a relative large number of bits. Huffman
algorithm used to an application for JPEG. The advantages of easy to implement
and It is an optimal and compact code. The disadvantage is algorithm can relatively
slow. It depends on the statistical model of data. The decoding process
difficult and different code length

 

AREA CODING:-

       The area coding enhanced from run length
coding of lossless compression technique. It is a highly effective which is
provides a better compression ratio (CR). It reflect the two dimensional
character of image. But it produces a  limitation.
It cannot implement the hardware because of non-linear method.  The advantage of the area coding technique
using over lossless other methods. It is used to special code words which is identifying
the large areas of contiguous 0’s and 1’s. The image can be segmented into a
blocks. Segments are classified as block. It only contains a black and white pixels
or block with mixed intensity and all pixels of the block have same value.

 

LZW CODING:-

           LZW is a
Lemple-Ziv-Welch.LZW based on the dictionary. The dictionary is classified in
two. One is represent a static and another one is represent dynamic. The static
perform a dictionary for fixed encoding. Dynamic perform a dictionary is
updated for decoding process. The applications are used as a TIFF and GIF
files. The advantage of lzw coding is easy to implement and compression perform
is fast.

The
disadvantages are to make string table is difficult and storage need an
indeterminate.

 

LOSSY COMPRESSION:-

                       Lossy
compression techniques perform a data can be compressed and loss of information.
Various lossless compression techniques
compared
higher compression ratio in reconstruction of the image. It provides a quality
of data for better compression. It performs to remove redundancy of the
original images. The following methods are using for lossy technique.

Ø Transform
coding

Ø  Vector
Quantization

Ø  Wavelet
coding

Ø  Fractal
coding

TRANSFORM CODING:-

             Transform coding is one of the Lossy
compression techniques in which the original image can be into small blocks of
smaller size. This technique is used as a data audio signal or biomedical
image. This type of coding required a lesser bandwidth.

Transform
coding use DCT (discrete coding transform) which is perform as used to change
the pixel of the original image. The widely used for the transform coding, JPEG
image compression standard adopted transform coding technique.

 

VECTOR QUANTIZATION:-

            Vector Quantization is one of the
most lossy compression techniques. VQ is a very powerful technique for digital
image compression. VQ extension of scalar quantization but with multiple
dimensions. VQ need to develop for code vectors which dictionary performs a
fixed-size of vectors.  Which means image
again divided into non-overlapping blocks, this are knows as image
vectors.   The dictionary is determined closest
matching vector for each image vector. The original image vector is encoded
which is use for the dictionary. It is widely used as a multimedia
application.  The advantage VQ is simple
decoder and no coefficient quantization. The Disadvantages is generating a slow codebook and Small bpp.

 

WAVELET CODING:-

 Wavelet coding is one of the most popular lossy
compression technique, Wavelet means a “smallwave” the waves are implies to a
window function of finite length. Wavelet functions are approach mathematics.
Wavelet Compression algorithm performing a Discrete Wavelet Transform (DWT).
Such as a Embedded Zero Wavelet (EZT) performance is excellent. The compression
quantization of the image which is specified the wavelet space image of sub-band.
Image compressions do the encoding of sub-band. Inverse or Reverse order
successively perform the image decompression, or reconstruction and which
decode, dequantize and inverse Discrete Wavelet Transformation.    The advantages is a high compression ratio,
State-Of-The- Art, low encoding complexity and It produce no blocking
artifacts. The Disadvantages is Coefficient Quantization, Bit allocation and less efficient

 

FRACTAL CODING:-

            It  is 
one  of  the most 
lossy  compression  technique 
used  in  digital 
images. It mainly based on the fractals. This approach natural images,
edge detection, color separation, spectrum and textures analysis. It performs the
fact parts of an image and resembles other parts of the same image. This are
convert parts into mathematical data. These data are called “fractal codes”. Which
are used to recreate the encoded image. The advantage is a good mathematical
encoding-frame and resolution encoding. The disadvantages is a slow encoding

CONCLUSION:-

            Basic  concept 
of  image  compression 
and  various  technologies 
used  are  discussed 
in  this  paper. 
We  have  also 
discussed  advantages  and 
disadvantages  of  some 
lossless image compression   and
lossy image  compression  techniques. A survey is performed on the most
essential and advance compression methods, in lossless technique the image can
be decoded without any loss of information. But in case of lossy compression it
cause some form of information loss. These techniques are good for various
applications. Lossy compression is most commonly used to compress multimedia
data like audio, video, and still images, especially in applications such as
streaming media. By contrast, lossless compression is required for text and data
files, such as bank records and text articles. Quality of image, amount of
compression and speed of compression.

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