27-09-2014, 04:29 PM
Abstracts: Image compression is a process that creates a compact representation of image with reduction in the size of image. It is necessary to compress an image for many modern world applications especially for the speed of accessing and sending an image in various media. Generally an image usually contains a large amount of data for a good picture quality, thus requiring large memory to store it well. One way to reduce waste of memory is to perform image compression. One of the compression algorithm can be used is a Block Truncation Code (BTC). BTC is a simple and lossy image compression technique. BTC has the advantage of being easy to implement compared to vector quantization and transform coding. BTC algorithm has good ability to compress an image with the complexity of the algorithm is not so difficult. JPEG image compression standard use DCT (DISCRETE COSINE TRANSFORM). The discrete cosine transform 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 DCT gives good compromise between information packing ability and computational complexity. DWT can be used to reduce the image size without losing much of the resolutions computed and values less than a pre-specified threshold are discarded. Thus it reduces the amount of memory required to represent given image.