IMAGE COMPRESSION AND DECOMPRESSION USING OVERLAPPED COSINE TRANSFORMS

An image processing apparatus and method that completely removes blocking artifacts from a compressed and restored digitized image. A compressed image is formed by windowing pixel data with a smooth window (discrete cosine transform) and then folding (wrapping) the windowed pixel data to form a modified image that is the same size as the original image. The wrapped and folded image is thereafter processed using a conventional discrete cosine transform and coder to produce the compressed image. To restore the original image, an inverse discrete cosine transform is used to process the compressed image, then the pixel data is unfolded (unwrapped), windowed, and combined to form the restored image. The present invention may be used to process data, such as voice signals, and images other than radiological images. The transform used in the present invention may also be a Fourier transform, for example.