Image processor, image forming apparatus, method of processing image

An image processor comprising:

• an input data corrector that corrects image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• an output tone value determining unit that determines an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• an error value calculator that calculates a difference between the output tone data and the corrected image data as an error value, wherein
• the output tone value determining unit sets the threshold in such a manner that a mean error value obtained from error values calculated by the error value calculator falls within a predetermined range regardless of the input tone value.

An image processor comprising:

• an input data corrector that corrects image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• an output tone value determining unit that determines an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• an error value calculator that calculates a difference between the output tone data and the corrected image data as an error value, wherein
• the output tone value determining unit sets the threshold in such a manner that a mean error value obtained from error values calculated by the error value calculator with respect to a change in the input tone value is substantially any one of a monotonous decrease and a monotonous increase with respect to the input tone value.

An image processor comprising:

• an input data corrector that corrects image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• an output tone value determining unit that determines an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• an error value calculator that calculates a difference between the output tone data and the corrected image data as an error value, wherein
• the output tone value determining unit sets the threshold from a threshold range determined by obtaining respective corrected image data corresponding to a plurality of output dot patterns output as output tone values in a steady state, to determine the threshold range for defining the obtained respective corrected image data.

An image processor comprising:

• an input data corrector that corrects image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• an output tone value determining unit that outputs any one of N (N>2) output tone values based on comparison of corrected image data of the target pixel and a threshold corresponding to the target pixel;
• and
• an error value calculator that calculates a difference between the output tone value and the corrected image data as an error value, wherein
• the output tone value determining unit determines the output tone value set so as to exclude a tone value in a predetermined range, with respect to a predetermined pixel position.

An image forming apparatus comprising:

• a data converter configured to receive image data and to convert image data of each of a plurality of pixels to a tone value;
• an image processor that processes the tone values thereby obtaining output image data;
• and
• an image output device that outputs an image based on the output image data, wherein
• the image processor comprises includes
• an input data corrector that corrects image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• an output tone value determining unit that determines an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• an error value calculator that calculates a difference between the output tone data and the corrected image data as an error value, wherein
• the output tone value determining unit sets the threshold in such a manner that a rate of change of a mean error value obtained from error values calculated by the error value calculator with respect to a change in the input tone value falls within a predetermined range.

An image forming apparatus comprising:

• a data converter configured to receive image data and to convert image data of each of a plurality of pixels to a tone value;
• an image processor that processes the tone values thereby obtaining output image data;
• and
• an image output device that outputs an image based on the output image data, wherein
• the image processor comprises includes
• an input data corrector that corrects image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• an output tone value determining unit that determines an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• an error value calculator that calculates a difference between the output tone data and the corrected image data as an error value, wherein
• the output tone value determining unit sets the threshold in such a manner that a mean error value obtained from error values calculated by the error value calculator falls within a predetermined range regardless of the input tone value.

An image forming apparatus comprising:

• a data converter configured to receive image data and to convert image data of each of a plurality of pixels to a tone value;
• an image processor that processes the tone values thereby obtaining output image data;
• and
• an image output device that outputs an image based on the output image data, wherein
• the image processor comprises includes
• an input data corrector that corrects image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• an output tone value determining unit that determines an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• an error value calculator that calculates a difference between the output tone data and the corrected image data as an error value, wherein
• the output tone value determining unit sets the threshold in such a manner that a mean error value obtained from error values calculated by the error value calculator with respect to a change in the input tone value is substantially any one of a monotonous decrease and a monotonous increase with respect to the input tone value.

An image forming apparatus comprising:

• a data converter configured to receive image data and to convert image data of each of a plurality of pixels to a tone value;
• an image processor that processes the tone values thereby obtaining output image data;
• and
• an image output device that outputs an image based on the output image data, wherein
• the image processor comprises an output tone value determining unit that outputs any one of N (N>2) output tone values based on comparison of an input tone value of a target pixel and a threshold corresponding to the target pixel position, and
• the output tone value determining unit determines the output tone value set so as to exclude a tone value in a predetermined range, with respect to a predetermined pixel position.

A method of image processing comprising:

• correcting image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• determining an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• calculating a difference between the output tone data and the corrected image data as an error value, wherein
• the determining includes setting the threshold in such a manner that a rate of change of a mean error value obtained from error values calculated at the calculating with respect to a change in the input tone value falls within a predetermined range.

A method of image processing comprising:

• correcting image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• determining an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• calculating a difference between the output tone data and the corrected image data as an error value, wherein
• the determining includes setting the threshold in such a manner that a mean error value obtained from error values calculated at the calculating falls within a predetermined range regardless of the input tone value.

A method of image processing comprising:

• correcting image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• determining an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• calculating a difference between the output tone data and the corrected image data as an error value, wherein the determining includes setting the threshold in such a manner that a mean error value obtained from error values calculated at the calculating with respect to a change in the input tone value is substantially any one of a monotonous decrease and a monotonous increase with respect to the input tone value.

A method of image processing comprising:

• correcting image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• determining an output tone data of the target pixel based on corrected image data, and a threshold corresponding to a position of the target pixel;
• and
• calculating a difference between the output tone data and the corrected image data as an error value, wherein
• the determining includes setting the threshold from a threshold range determined by obtaining respective corrected image data corresponding to a plurality of output dot patterns output as output tone values in a steady state, to determine the threshold range for defining the obtained respective corrected image data.

A method of image processing comprising:

• correcting image data of a target pixel by giving a weight to error values in the neighborhood of the target pixel and adding weighted error values to a tone value of the target pixel;
• outputting any one of N (N>2) output tone values based on comparison of corrected image data of the target pixel and a threshold corresponding to the target pixel;
• and
• calculating a difference between the output tone value and the corrected image data as an error value, wherein
• the outputting includes determining the output tone value set so as to exclude a tone value in a predetermined range, with respect to a predetermined pixel position.