Image signal conversion apparatus and method

摘要

An image signal expressing pel values and a significance signal, declaring for each pel whether the pel value is significant, are supplied as input signals. By referring to the input significance signal values for the pels proximal to the pel being processed, the significant pels are identified and a resolution conversion characteristics selector selects one of two or more frequency conversion characteristics to be used for resolution conversion of the image signal using only significant pels. A resolution converter then converts the resolution of the input image signal using the selected resolution conversion characteristic, and outputs the result as the image conversion apparatus output signal. Resolution conversion of the input image signal can therefore be accomplished by means of pel subsampling or interpolation without being affected by nonsignificant pels, and resolution conversion with minimal image quality loss caused by the conversion process is achieved.