Comparative Study of Loss-Less & Lossy Images Compression
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Date
2016-08-23T10:21:08Z
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With the wide use of computers and consequently need for large scale storage and transmission of data, efficient ways of storing data have become necessary. With the growth of technology and entrance into the Digital Age, the world has found itself amid a vast amount of information.
Dealing with such enormous information can often present difficulties. The purpose of data compression is to make a file smaller by minimizing the amount of data present. When a file is compressed, it can be reduced to as little as 25% of its original. It is done to reduce the amount of space it takes to save the data wherever the data is stored and also makes it better to send through the internet if the files are large. Many files can be combined into one compressed document making it easier.
Image compression is minimizing the size in bytes of a graphics file without degrading the quality of the image to an unacceptable level. The reduction in file size allows more images to be stored in a given amount of disk or memory space. It also reduces the time required for images to be sent over the Internet or downloaded from Web pages. JPEG is an important techniques used for image compression.
JPEG image compression standard uses Discrete Cosine Transform (DCT). It is a fast transform. It is a widely used and robust method for image compression. It has excellent compaction for highly correlated data. DCT has fixed basis images. It gives good compromise between information packing ability and computational complexity.
Compressing an image is significantly different than compressing raw binary data. Of course, general purpose compression programs can be used to compress images, but the result is less than optimal. DCT has been widely used in signal processing of the image. The one-dimensional DCT is useful in processing one-dimensional signals such as speech waveforms. For analysis of two- dimensional (2D) signals such as images, we need a 2D version of the DCT data, especially in coding for compression, for its near-optimal performance.
With the use of digital cameras, requirements for storage, manipulation, and transfer of digital images has grown explosively. These image files can be very large and can occupy a lot of memory. A gray scale image that is 256 x 256 pixels has 65, 536 elements to store, and a typical 640 x 480 color image has nearly a million. Downloading of these files from internet can be very time consuming task.
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Sagar Simha K T, Garlapati Prudvi Charan, Sasngeetha M, Comparative Study of Loss-Less & Lossy Images Compression