An orthogonal transformation arithmetic unit performs a discrete cosine transformation with respect to a digital signal and compresses discrete cosine transformed data by quantizing and Huffman- coding processings thereof. The arithmetic unit Huffman-decodes the compressed data and demodulates the Huffman-decoded data to a digital signal by performing inverse quantization and an inverse discrete cosine transformation with respect to the Huffman-decoded data. The arithmetic unit has a memory section for storing one line block of image data of brightness and color signals converted to digital signals; and a section for processing the discrete cosine transformation and having a preprocessing circuit for performing adding and subtracting operations with respect to the image data read out of the memory section such that some values of discrete cosine transformation coefficients used in the discrete cosine transformation are partially set to zero. The other orthogonal arithmetic units are also shown.
展开▼
