Encoding method and encoding apparatus, and computer program and computer readable storage medium

An encoding apparatus for re-encoding encoded data, which is represented by a data format of a runlength code part indicating a runlength of the same data and a data part indicating the data, and a runlength code part indicating a runlength of different data and a data part indicating the different data, to that data format, comprising:

• input means for inputting encoded data in the data format;
• separation means for separating a runlength code part and a data part from the input encoded data;
• change means for changing a desired bit in the separated data part;
• reconstruction means for reconstructing the data format on the basis of the changed data part and the runlength code part without decoding the input encoded data;
• and
• output means for outputting the reconstructed data as re-encoded data.

A computer program functioning as an encoding apparatus for re-encoding encoded data, which is represented by a data format of a runlength code part indicating a runlength of the same data and a data part indicating the data, and a runlength code part indicating a runlength of different data and a data part indicating the different data, to that data format, said program functioning as:

• input means for inputting encoded data in the data format;
• separation means for separating a runlength code part and a data part from the input encoded data;
• change means for changing a desired bit in the separated data part;
• reconstruction means for reconstructing the data format on the basis of the changed data part and the runlength code part without decoding the input encoded data;
• and
• output means for outputting the reconstructed data as re-encoded data.

An image forming apparatus comprising:

• an image compression encoding unit, adapted to compression encode image data for one page and to store encoded image data in a first storage unit;
• an image area determination unit, adapted to determine an image area of each pixel data of the image data, information indicating an image area determination result being 1 byte data, and determination results for respective image area types being assigned to respective bits;
• an image area compression encoding unit, adapted to compression-encode the image area information of each pixel obtained by said image area determination unit, and to store the encoded image area information in a second storage unit;
• a decoding unit, adapted to decode the encoded data stored in the first storage unit and the encoded data stored in the second storage unit;
• and
• a print unit, adapted to correct the decoded image data on the basis of the decoded image area information, and print the corrected image data,
• wherein said image area compression encoding unit comprises:
• a mask unit, adapted to mask a desired bit of the image area information of one pixel obtained from said image area determination unit;
• a PackBits encoder, adapted to PackBits encode the image area information masked by said mask unit, and store the PackBits encoded image area information in the second storage unit;
• and
• a monitor unit, adapted to monitor a code size in the second storage unit, and, when the PackBits code size stored in the second storage unit reaches a predetermined size during encoding of image area information for one page, re-encode PackBits encoded data stored in the second storage unit by masking a predetermined bit of a data part of the PackBits encoded data, re storing the re-encoded data in the second storage unit, and setting said mask unit to mask the predetermined bit of image area information to be input subsequently.

A method of controlling an image forming apparatus comprising:

• an image compression encoding step, of compression encoding image data for one page and storing encoded image data in a first storage unit;
• an image area determination step, of determining an image area of each pixel data of the image data, information indicating an image area determination result being 1 byte data, and determination results for respective image area types being assigned to respective bits;
• an image area compression encoding step, of compression encoding the image area information of each pixel obtained in said image area determination step, and storing the encoded image area information in a second storage unit;
• a decoding step, of decoding the encoded data stored in the first storage unit and the encoded data stored in the second storage unit;
• and
• a print step, of correcting the decoded image data on the basis of the decoded image area information, and printing the corrected image data,
• in which said image area compression encoding step comprises:
• a mask step, of masking a desired bit of the image area information of one pixel obtained in the image area determination step;
• a PackBits encoding step, of PackBits-encoding the image area information masked in the mask step, and storing the PackBits encoded image area information in the second storage unit;
• and
• a monitor step, of monitoring a code size in the second storage unit, re-encoding, when the PackBits code size stored in the second storage unit reaches a predetermined size during encoding of image area information for one page, PackBits encoded data stored in the second storage unit by masking a predetermined bit of a data part of the PackBits encoded data, re-storing the re-encoded data in the second storage unit, and setting said mask step to mask the predetermined bit of image area information to be input subsequently.

An encoding method for re-encoding encoded data, which is represented by a data format of a runlength code part indicating a runlength of the same data and a data part indicating the data, to the data format, comprising:

• a step of inputting encoded data in the data format;
• a step of acquiring a runlength code part and a data part from the input encoded data;
• a step of changing a desired part in the acquired data part;
• and
• a step of reconstructing the data format on the basis of the changed data part and the runlength code part without decoding the input encoded data.

An encoding apparatus for re-encoding encoded data, which is represented by a data format of a runlength code part indicating a runlength of the same data and a data part indicating the data, to the data format, comprising:

• input means for inputting encoded data in the data format;
• acquisition means for acquiring a runlength code part and a data part from the input encoded data;
• changing means for changing a desired part in the acquired data part;
• and reconstruction means for reconstructing the data format on the basis of the changed data part and the runlength code part without decoding the input encoded data.

A computer program functioning as an encoding apparatus for re-encoding encoded data, which is represented by a data format of a runlength code part indicating a runlength of the same data and a data part indicating the data, to the data format, said program functioning as:

• input means for inputting encoded data in the data format;
• acquisition means for acquiring a runlength code part and a data part from the input encoded data;
• changing means for changing a desired part in the acquired data part;
• and
• reconstruction means for reconstructing the data format on the basis of the changed data part and the runlength code part without decoding the input encoded data.