System and apparatus for single subpixel elimination with local error compensation in a high addressable error diffusion process

A system for processing image data, comprising:

• means for converting a pixel of image data having a first resolution to a plurality of subpixels, the plurality of subpixels representing a second resolution, the second resolution being higher than the first resolution;
• means for thresholding the plurality of subpixels to generate a group of subpixel values for each pixel and a threshold error value;
• analysis means for determining if the group of subpixel values from the thresholding process produces an undesirable pattern;
• modification means for modifying the group of pixel values to eliminate the undesirable pattern when said analysis means makes a positive determination;
• error means for generating a plurality of modification subpixel error values based on the modification by said modification means;
• and
• compensation means for compensating the threshold error values for pixels in adjacent pixels based on the modification subpixel error values in conjunction with a set of weighting coefficients.

An image data processing method comprising:

• receiving a pixel of image data having a first resolution;
• converting the received pixel of image data to a plurality of subpixels, the plurality of subpixels representing a second resolution higher than the first resolution;
• thresholding the plurality of subpixels to generate a group of subpixels for each pixel and a threshold error value for each pixel;
• determining if the group of subpixel values from the thresholding process produces an undesirable pattern;
• modifying the group of subpixel values to eliminate the undesirable pattern when determining if the group of subpixel values from the thresholding process produces an undesirable pattern includes making a positive determination;
• generating a plurality of modification subpixel error values based on results of modifying the group of subpixel values;
• compensating the threshold error values for pixels in adjacent pixels based on the modification subpixel error values generated in said step in conjunction with a set of weighting coefficients;
• diffusing the threshold error values to adjacent pixels based on a set of weighting coefficients;
• and
• diffusing the modification subpixel error values to adjacent pixels based on a set of weighting coefficients related to the weighting coefficients used to diffuse the threshold error values.

An image data processing method comprising:

• receiving a pixel of image data having a first resolution;
• converting the received pixel of image data to a plurality of subpixels, the plurality of subpixels representing a second resolution, the second resolution being higher than the first resolution;
• thresholding the plurality of subpixels to generate a group of subpixels for each pixel and a threshold error value for each pixel;
• determining if the group of subpixel values from the thresholding process produces an undesirable pattern;
• modifying the group of subpixel values to eliminate the undesirable pattern when determining if the group of subpixel values from the thresholding process produces an undesirable pattern includes making a positive determination;
• generating a plurality of modification subpixel error values based on results of modifying the group of subpixel values by:
• comparing adjacent modification subpixel error values;
• and
• assigning the modification subpixel error value that has the smaller absolute value to a value of zero and the other adjacent modification subpixel value to a value equal to a sum of the two original adjacent modification subpixel error values when the two compared adjacent modification subpixel error values are of different polarity;
• and
• compensating the threshold error values for pixels in adjacent pixels based on the modification subpixel error values generated in said step in conjunction with a set of weighting coefficients.

An image data processing system comprising:

• an image data pixel converter that converts a pixel of image data having a first resolution to a plurality of subpixels, the plurality of subpixels representing a second resolution higher than the first resolution;
• a subpixel thresholder that thresholds the plurality of subpixels to generate a group of subpixel values for each pixel and a threshold error value;
• a subpixel group analyzer that determines if the group of subpixel values from the thresholding process produces an undesirable pattern;
• a pixel group modifier that modifies the group of pixel values to eliminate the undesirable pattern when said analysis means makes a positive determination;
• an error generator that generates a plurality of modification subpixel error values based on the modification by said modification means;
• an error compensator that compensates the threshold error values for pixels in adjacent pixels based on the modification subpixel error values in conjunction with a first set of weighting coefficients;
• and
• an error diffuser that diffuses the threshold error values to adjacent pixels based on a second set of weighting coefficients related to the first set of weighting coefficients.

An image data processing system comprising:

• an image data pixel converter that converts a pixel of image data having a first resolution to a plurality of subpixels, the plurality of subpixels representing a second resolution higher than the first resolution;
• a subpixel thresholder that thresholds the plurality of subpixels to generate a group of subpixel values for each pixel and a threshold error value;
• a subpixel group analyzer that determines if the group of subpixel values from the thresholding process produces an undesirable pattern;
• a pixel group modifier that modifies the group of pixel values to eliminate the undesirable pattern when said analysis means makes a positive determination;
• an error generator that generates a plurality of modification subpixel error values based on the modification by said modification means;
• and
• an error compensator that compensates the threshold error values for pixels in adjacent pixels based on the modification subpixel error values in conjunction with a set of weighting coefficients, the error compensator assigning a modification subpixel error value that has the smaller absolute value to a value of zero, and assigning an adjacent modification subpixel value to a value equal to a sum of the two original adjacent modification subpixel error values when the adjacent modification error pixel values are of different polarity.

A data image processing method comprising:

• compensating threshold error values for pixels of image data in adjacent pixels based on a plurality of modification subpixel error values in conjunction with a set of weighting coefficients;
• and
• generating the plurality of modification subpixel error values based on a modified group of subpixel values generated by:
• receiving a pixel of image data having a first resolution;
• converting the received pixel of image data to a plurality of subpixels, the plurality of subpixels representing a second resolution higher than the first resolution;
• thresholding the plurality of subpixels to generate a group of subpixels for each pixel and a threshold error value for each pixel;
• determining if the group of subpixel values from the thresholding process produces an undesirable pattern;
• and
• modifying the group of subpixel values to eliminate the undesirable pattern when determining if the group of subpixel values from the thresholding process produces an undesirable pattern includes making a positive determination.