System and method for coding and/or decoding image including bit-map of different levels

A system for recording image data, comprising:

• a block divider configured to divide a bitmap image composed of picture elements into blocks including a plurality of said picture elements;
• a first discriminator configured to discriminate as to whether each of said blocks is a block of small-level where resolution information is important or a block of multilevel where tone information is important;
• a first coding part configured to transform said block of small-level into a first code-row representative of only a number of black or half-tone picture elements in said block of small-level;
• wherein said first coding part includes local decoding means for decoding codes respective of said number of black or half-tone picture elements in which a block of small-level vary in each of the blocks, and comparing means for comparing the decoded data obtained by said local decoding means with the small-level of a corresponding block and for discriminating as to whether both of the data coincide with each other;
• and
• a second coding part configured to transform said block of multilevel into a second code-row representative of an average density of said picture elements in the block;
• an assigner configured to assign said first code-row and said second code-row to respective codes positioned in accordance with a rule of common codes;
• wherein said assignor further assigns an error to a third code-row of the common codes of said digital data, when the comparing means discriminates that said decoded data do not coincide with the small-level of the corresponding block
• a storing part configured to store said common codes;
• a second discriminator configured to read said common codes stored in said storing part, and configured to discriminate as to whether code data in said common codes belong to said first code-row or said second code row;
• a first decoding part configured to restore bitmap data of said block of small-level from surrounding blocks in said common codes information and/or bitmap data information;
• a second decoding part configured to reversely transform the code representing multiple bit-map data into multiple bit-map data;
• and
• a recording part configured to record decoded bit-map data by said first decoding means and said second decoding means.

A method for recording image data, comprising:

• a first step of dividing a bitmap image which is composed of picture elements into blocks including a plurality of said picture elements;
• a second step of discriminating as to whether each of said blocks is a block of small-level where resolution information is important or a block of multilevel where tone information is important;
• a third step of transforming said block of small-level into a first code-row representative bf only a number of black or half-tone picture elements in said block of small-level;
• a fourth step of transforming said block of multilevel into a second code-row representative of an average density of said picture elements in the block;
• wherein said fourth step further comprises the steps of:
• comparing the decoded data obtained by decoding the code transformed by said third step, with the small-level of the corresponding block;
• assigning the code to said first code-rows of the common codes of digital data of the predetermined bit-number when both of the data coincide with each other;
• and
• assigning an error code representative of the occurrence of an error to third code-rows of the common codes of said digital data when both of the data do not coincide with each other, thereby storing said small-level;
• a fifth step of assigning said first code-row and said second code-row to respective codes positioned in accordance with a rule of common codes;
• a sixth step of storing said common codes;
• a seventh step of reading said common codes stored in said sixth step;
• an eight step of discriminating as to whether code data in said common codes belong to said first code-row or said second code row;
• a ninth step of restoring bitmap data of said block of small-level by decoding from surrounding blocks in said common codes information and/or bitmap data information;
• a tenth step of reversely transforming the code representing multiple bit-map data into multiple bit-map data;
• and
• an eleventh step of recording decoded bit-map data in said ninth step and said tenth step.