Interpolation method and apparatus by correlation detection using fuzzy inference

An image processor for interpolating scan lines of an input image signal by determining an interpolation direction based on correlation between each pair of pixels located at intersections of one of plural interpolation lines passing a target pixel with scan lines located above and below said target pixel comprising:

• a calculation means for calculating a level difference between each pair of pixels located on one of said plural interpolation lines for all said plural interpolation lines;
• a fuzzy antecedent processing means comprising:
• a first membership function means for calculating a likelihood of correlation between each pair of pixels located on one of said plural interpolation lines based on the level difference of each pair of pixels calculated by said calculation means;
• a second membership function means for calculating an unlikelihood of correlation between a pair of pixels located on an interpolation line, having an opposite sign of slope of the interpolation line to which the likelihood of correlation is calculated, based on the level difference related to said interpolation line having an opposite sign of slope to the interpolation line to which the likelihood of correlation is calculated;
• and
• a judging means for judging a correlation between each pair of pixels by integrating said likelihood of correlation calculated by said first membership function means and said unlikelihood of correlation calculated by said second membership function means;
• a fuzzy consequent processing means for determining an interpolation direction based on results of judgement of said fuzzy antecedent processing means;
• and
• an interpolation means for interpolating said target pixel based on levels of pixels located on the interpolation line determined by said fuzzy consequent processing means.