Image forming apparatus

An image forming apparatus, comprising:

• a random dither processing unit that performs random dither processing of converting input N-values image data to M-values image data;
• a non-transitory memory configured to store the input N-values image data;
• a flag setting unit that sets a flag that designates an addition of a non-periodic component to each of quantization threshold values;
• and
• a threshold-value adding unit that adds a non-periodic component to the quantization threshold values based on a magnitude of the quantization threshold values in different threshold value levels with respect to a target pixel in the quantization threshold values,
• wherein, with respect to a quantization threshold value that periodically changes, a threshold value that has a non-periodic component is added to the quantization threshold value in pixels that form a core of a predetermined dither, while a threshold value that has a non-periodic component is not added to the quantization threshold value in the other pixels.

An image forming apparatus, comprising:

• a random dither processing unit that performs random dither processing of converting input N-values image data to M-values image data;
• a non-transitory memory configured to store the input N-values image data;
• a flag setting unit that sets a flag that designates an addition of a non-periodic component to each of quantization threshold values;
• a threshold-value adding unit that adds a non-periodic component to the quantization threshold values based on a magnitude of the quantization threshold values in different threshold value levels with respect to a target pixel in the quantization threshold values;
• and
• an input unit that receives input of information from a user that indicates whether a threshold value that has a non-periodic component is to be added to the quantization threshold values.

An image forming apparatus, comprising:

• a random dither processing unit that performs random dither processing of converting input N-values image data to M-values image data;
• a non-transitory memory configured to store the input N-values image data;
• a flag setting unit that sets a flag that designates an addition of a non-periodic component to each of quantization threshold values;
• and
• a threshold-value adding unit that adds a non-periodic component to the quantization threshold values based on a magnitude of the quantization threshold values in different threshold value levels with respect to a target pixel in the quantization threshold values,
• wherein a value to set whether a threshold value that has a non-periodic component is added to the quantization threshold values is switched by an input device of image data.