| 摘要 |
PURPOSE: To provide a method capable of improving the appearance of an extended document image while maintaining the faithfullness of the extended document image to its original document. CONSTITUTION: At the time of extension, a quantization transformation coefficient block encoded from an original image is received, all no loss encoded parts are removed from the block, respective quantization transformation coefficients in the block are respectively multiplied by corresponding quantization values obtained from a quantization table to obtain a received transformation coefficient block, and reverse transformation operation is applied to the received transformation coefficient to restore the image. A filter threshold is adaptively selected in each block, side edges in the block are detected to form the allocation of generation of the side edges and the image is repeatedly filtered by a smoothing filter. The filtering processing operation is controlled by a side edge map led so as not to operate the side edges of the image, each new transformation coefficient block is compared with its corresponding received transformation coefficient block and the contents of the quantization table, whether the filtered restored image can be led out from the original image or not is determined and the filtered restored image is transferred to an output butter in accordance with the determination. |
