Image data processing apparatus, image data processing method, and image data processing program

An image data processing method which inputs image data generated from an image represented in multiple gradations of dot matrix pixels, diffuses a gradation error for each pixel to the other unconverted pixels, and converts the input image data to image data represented by presence or absence of dot formation, the apparatus comprising:

• a block process determination step of forming a block by grouping a specified number of neighboring pixels and determining whether or not a specified block process condition is satisfied on the basis of a gradation value for each pixel in a target block to convert the image data;
• a first conversion step of, when the block process determination unit determines the block process condition to be true, diffusing a gradation error for the entire target block to unconverted pixels outside the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block and converting image data for pixels in the target block at a time;
• and
• a second conversion step of determining whether or not to form a dot in the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block when the block process determination step determines the block process condition to be false, of converting image data for pixels in the target block while diffusing a gradation error for the pixel partition to the other unconverted pixels on the basis of the gradation value and the diffused gradation error for each pixel according to each pixel partition comprising grouped pixels in the target block when it is determined that a dot is to be formed in the target block, and of converting image data for pixels in the target block at a time while diffusing a gradation error for the entire target block to the other unconverted pixels outside the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block when it is determined that no dot is to be formed in the target block.

An image data processing program for allowing a computer to implement a function which inputs image data generated from an image represented in multiple gradations of dot matrix pixels, diffuses a gradation error for each pixel to the other unconverted pixels, and converts the input image data to image data represented by presence or absence of dot formation, the program comprising:

• a block process determination function of forming a block by grouping a specified number of neighboring pixels and determining whether or not a specified block process condition is satisfied on the basis of a gradation value for each pixel in a target block to convert the image data;
• a first conversion function of, when the block process determination function determines the block process condition to be true, diffusing a gradation error for the entire target block to unconverted pixels outside the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block and converting image data for pixels in the target block at a time;
• and
• a second conversion function of determining whether or not to form a dot in the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block when the block process determination function determines the block process condition to be false, for converting image data for pixels in the target block while diffusing a gradation error for the pixel partition to the other unconverted pixels on the basis of the gradation value and the diffused gradation error for each pixel according to each pixel partition comprising grouped pixels in the target block when it is determined that a dot is to be formed in the target block, and for converting image data for pixels in the target block at a time while diffusing a gradation error for the entire target block to the other unconverted pixels outside the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block when it is determined that no dot is to be formed in the target block.

An image data processing apparatus which inputs image data generated from an image represented in multiple gradations of dot matrix pixels, diffuses a gradation error for each pixel to the other unconverted pixels, and converts the input image data to image data represented by presence or absence of dot formation, the apparatus comprising:

• a block process determination unit for forming a block by grouping a specified number of neighboring pixels and determining whether or not a specified block process condition is satisfied on the basis of only a gradation value for each pixel in a target block to convert the image data;
• a first conversion unit for diffusing a gradation error for the entire target block to unconverted pixels outside the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block and converting image data for pixels in the target block at a time when the block process determination unit determines the block process condition to be true;
• and
• a second conversion unit for being able to convert image data for pixels in the target block while diffusing a gradation error for the pixel partition to the other unconverted pixels on the basis of the gradation value and the diffused gradation error for each pixel according to each pixel partition comprising grouped pixels in the target block when the block process determination unit determines the block process condition to be false.

An image data processing method which inputs image data generated from an image represented in multiple gradations of dot matrix pixels, diffuses a gradation error for each pixel to the other unconverted pixels, and converts the input image data to image data represented by presence or absence of dot formation, the apparatus comprising:

• a block process determination step of forming a block by grouping a specified number of neighboring pixels and determining whether or not a specified block process condition is satisfied on the basis of only a gradation value for each pixel in a target block to convert the image data;
• a first conversion step of, when the block process determination unit determines the block process condition to be true, diffusing a gradation error for the entire target block to unconverted pixels outside the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block and converting image data for pixels in the target block at a time;
• and
• a second conversion step for being able to convert image data for pixels in the target block while diffusing a gradation error for the pixel partition to the other unconverted pixels on the basis of the gradation value and the diffused gradation error for each pixel according to each pixel partition comprising grouped pixels in the target block when the block process determination step determines the block process condition to be false.

An image data processing program for allowing a computer to implement a function which inputs image data generated from an image represented in multiple gradations of dot matrix pixels, diffuses a gradation error for each pixel to the other unconverted pixels, and converts the input image data to image data represented by presence or absence of dot formation, the program implementing:

• a block process determination function of forming a block by grouping a specified number of neighboring pixels and determining whether or not a specified block process condition is satisfied on the basis of only a gradation value for each pixel in a target block to convert the image data;
• a first conversion function of, when the block process determination function determines the block process condition to be true, diffusing a gradation error for the entire target block to unconverted pixels outside the target block on the basis of the gradation value and the diffused gradation error for each pixel in the target block and converting image data for pixels in the target block at a time;
• and
• a second conversion function of being able to convert image data for pixels in the target block while diffusing a gradation error for the pixel partition to the other unconverted pixels on the basis of the gradation value and the diffused gradation error for each pixel according to each pixel partition comprising grouped pixels in the target block when the block process determination function determines the block process condition to be false.

The image data processing apparatus according to claim, wherein the conversion unit comprises:

• a determination unit for forming a block comprising two or more neighboring pixels and determining whether or not a specified block process condition is satisfied on the basis of a gradation value for each pixel in a target block converting the image data;
• a first conversion unit for assuming the target block to be the target conversion partition and converting the image data for the entire target block at a time when the determination unit determines the block process condition to be true;
• and
• a second conversion unit for being able to convert image data for pixels in the target block while using a pixel partition comprising grouped pixels in the target block as the conversion partition and diffusing a gradation error for the pixel partition to the other unconverted pixels on the basis of the gradation value and the diffused gradation error for each pixel when the block process determination unit determines the block process condition to be false.