Optical reproducing system for multimedia information recorded with code data having function for correcting image reading distortion

An information reproducing apparatus comprising:

• image pickup means for optically reading, from an information recording medium which comprises a portion that records multimedia information including at least one of audio information, video information, and digital code data in the form of an optically readable code pattern, the code pattern;
• conversion means for converting the code pattern read by said image pickup means into code data as an image;
• marker detection means for detecting a plurality of markers representing boundaries of a block upon extraction of the block as a predetermined unit of data from the code data by processing the code data converted by said conversion means;
• marker rough center calculation means for calculating rough centers of the markers detected by said marker detection means;
• pattern code detection means for detecting a pattern code constituted by a plurality of dots with reference to the rough centers of the markers calculated by said marker rough center calculation means;
• pattern code dot center calculation means for calculating centers of the dots of the pattern code detected by said pattern code detection means;
• marker true center calculation means for calculating coordinate positions of a plurality of true centers of the markers that minimize evaluation functions representing relative coordinate errors of the center coordinate positions of the dots of the pattern code calculated by said pattern code dot center calculation means and center coordinate positions of dots of a predetermined pattern code with respect to the true center coordinate positions of the markers;
• data reading coordinate calculation means for calculating a data reading coordinate position in the block on the basis of the coordinate positions of the plurality of true centers of the markers calculated by said marker true center calculation means;
• data reading coordinate discrimination means for discriminating whether the data reading coordinate position calculated by said data reading coordinate calculation means indicates a center or boundary of a pixel constituting the image by performing a calculation at an accuracy not less than a predetermined multiple of the pixel constituting the image;
• reading pixel black/white discrimination means for, when said data reading coordinate discrimination means determines that the data reading coordinate position indicates the center of the pixel constituting the image, extracting information from one pixel on the image indicated by the data reading coordinate position;
• and
• reading surrounding pixel black/white discrimination means for, when said data reading coordinate discrimination means determines that the data reading coordinate position indicates the boundary of the pixel constituting the image, extracting information from a plurality of pixels contacting the boundary indicated by the data reading coordinate position and discriminating vanishing data indicating whether or not information is indefinite.