Image processing method that attempts decoding of additional information using a plurality of decoding methods, and apparatus therefor

An image processing method, performed by a processor executing a program stored in a memory, of acquiring additional information from image information obtained by shooting a printed product on which the additional information is multiplexed by a multiplexing method, comprising:

• attempting decoding of the additional information from the image information by a plurality of different decoding methods;
• and
• outputting the additional information successfully decoded,
• wherein in the attempting decoding, the decoding of the additional information is attempted for the entire image information by each of the plurality of different decoding methods.

An image processing method, performed by a processor executing a program stored in a memory, of acquiring additional information from image information obtained by shooting a printed product on which the additional information is multiplexed by at least one of a plurality of different multiplexing methods, comprising:

• attempting decoding of the additional information from the image information by a plurality of different decoding methods corresponding to the plurality of different multiplexing methods;
• and
• outputting the additional information successfully decoded,
• wherein in the attempting decoding, the decoding of the additional information is attempted for each region included in the image information by each of the plurality of different decoding methods.

An image processing method, performed by a processor executing a program stored in a memory, of acquiring additional information from image information obtained by shooting a printed product on which the additional information is multiplexed by at least one of a plurality of different multiplexing methods, comprising:

• attempting decoding of the additional information from the image information by a plurality of different decoding methods corresponding to the plurality of different multiplexing methods;
• and
• outputting the additional information successfully decoded,
• wherein the plurality of different multiplexing methods includes, as one multiplexing method, a first multiplexing method of, for each block formed by dividing the image information, quantizing the block using a quantization threshold matrix corresponding to a code of the additional information, thereby multiplexing the additional information, and
• in the attempting decoding, a level of matching between a spatial frequency of the image information included in the block and a spatial frequency of a pattern of the quantization threshold matrix is determined, and if the level of matching is more than a predetermined value, the code corresponding to the quantization threshold matrix is decoded.

An image processing apparatus for acquiring additional information from image information obtained by shooting a printed product on which the additional information is multiplexed by at least one of a plurality of different multiplexing methods, comprising:

• a processor;
• and
• a memory which stores a program,
• wherein the processor, by executing the program stored in the memory, attempts decoding of the additional information from the image information by a plurality of different decoding methods corresponding to the plurality of different multiplexing methods, and
• the processor, by executing the program stored in the memory, outputs the additional information successfully decoded, and
• wherein the additional information is multiplexed for each block formed by dividing the image information, and
• in the attempting decoding, the processor attempts the decoding of the additional information for each block by each of the plurality of different decoding methods, and decodes a rest of the image information by the decoding method that has succeeded in the decoding.