K.Mahendra Babu , Dr. P. Sathyanarayana
This paper entails the study of various image compression techniques and algorithms for natural and compound images. „Compound images‟ are defined as images that contain a combination of text, natural (photo) images and graphic images. Different techniques for digital image compression have been reviewed and presented that include DCT, JPEG and H.264. The discrete cosine transform (DCT) is a technique for converting a signal into elementary frequency components. It is widely used in image compression. Here we develop some simple functions to compute the DCT and to compress images. JPEG is the popular compression standard used exclusively for still images. Each image is divided in 8 × 8pixels; each block is then individually compressed. When using a very high compression the 8 × 8 blocks can be actually seen in the image. Due to the compression mechanism, the decompressed image is not the same image which has been compressed. A H.264 algorithm that suits both compound and natural images is beneficial in many applications including the Internet. Experimental results show that the H.264 algorithm is better PSNR values for natural and compound images to compare other techniques
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