G. Zeng (USA)
Image coding, JPEG, Fractalcompression, IFS, PIFS.
At present, due to the limited frequency bandwidth, a very high compression ratio is required to transmit video image over the Internet. In this case, the DCT (Discrete Cosine Transform) used in JPEG and MPEG suffers from blocky artefacts. We naturally recall the fractal image compression which can obtain high compression ratio. But the fractal encoding is much slower than the DCT encoding. In this paper, we propose a new way to combine the fractal method with the DCT method to reduce the encoding time and increase the compression ratio. The key idea is how to classify images into fractal and non-fractal. It turns out that a fractal image is rich in high spatial frequency components. It is natural to use fractal method for a fractal image. The DCT method is employed for nonfractal images. In this way, we achieved an encoding speed much faster than the traditional fractal method, and a compression ratio greater than the DCT method. Additional advantage of the proposed method is when you download an image from the Internet. You can recognize what is being downloaded at an early stage. If it is not what you want you can stop the downloading immediately. But in the JPEG you must wait until the downloading is almost completed.
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