Image processing device and image processing method

An image processing device that executes a pseudo halftone process on multivalued image data comprising a plurality of planes, the device comprising:

• a component allowing image data with a plurality of planes to be input to the device;
• a component weighting a quantization error near a target pixel for each of the plurality of planes;
• a adding component adding the weighted quantization error to the input image data;
• a component setting a threshold for each of the plurality of planes;
• a plurality of quantizing components quantizing the input image data based on the set threshold for each of the plurality of planes;
• a first quantization error calculating component calculating a plurality of quantization errors resulting from the quantizing process of the quantizing component;
• a determining component determining how to correct an output from the quantizing component on the basis of signs of the calculated plurality of quantization errors;
• a component generating a correction value on the basis of a sum of the plurality of quantization errors and the predetermined threshold;
• a component correcting the output from the quantizing component using the correction value;
• and
• a second quantization error calculating component calculating a quantization error from the corrected output from the quantizing component and inputting the calculation to the component weighting the quantization error.

An image processing method of executing a pseudo halftone process on multivalued image data comprising a plurality of planes, comprising the steps of:

• allowing image data with a plurality of planes to be input;
• weighting a quantization error near a target pixel for each of the plurality of planes;
• adding the weighted quantization error to the input image data;
• setting a threshold for each of the plurality of planes;
• quantizing the input image data based on the set threshold for each of the plurality of planes;
• calculating a plurality of quantization errors resulting from the quantizing process in the quantizing step;
• determining how to correct the quantization output on the basis of signs of the calculated plurality of quantization errors;
• generating a correction value on the basis of a sum of the plurality of quantization errors and the predetermined threshold;
• correcting the quantization output using the correction value;
• and
• calculating a quantization error from the corrected quantization output.

A computer-readable storage medium containing a program to direct a computer to execute the steps of:

• allowing image data with a plurality of planes to be input to the computer;
• weighting a quantization error near a target pixel for each of the plurality of planes;
• adding the weighted quantization error to the input image data;
• setting a threshold for each of the plurality of planes;
• quantizing the input image data based on the set threshold for each of the plurality of planes;
• calculating a plurality of quantization errors resulting from the quantizing process in the quantizing step;
• determining how to correct the quantization output on the basis of signs of the calculated plurality of quantization errors;
• generating a correction value on the basis of a sum of the plurality of quantization errors and the predetermined threshold;
• correcting the quantization output using the correction value;
• and
• calculating a quantization error from the corrected quantization output.