METHOD AND APPARATUS FOR EXTRACTING PIXEL VALUES

The luminance and chrominance values of pixels encoded according to MPEG or JPEG encoding are extracted using a forward discrete cosine transform (DCT). The forward DCT used in MPEG encoding is analyzed to derive a set of equations which directly relate a pixel value in an encoded image to one or more of the DCT coefficients obtained via the forward DCT transform in the usual image encoding process. These predetermined equations are used to allow for extremely fast and computationally efficient extraction of pixel values directly from the DCT coefficients of an encoded pixel block, without having to undergo an inverse DCT transform. Original images from MPEG and JPEG encoded versions may be extracted in a fast and efficient manner.