Image processing apparatus and method for performing error diffusion based on density values of different color components

An image processing apparatus for performing error diffusion processing on multivalued image data having plural density components and outputting a result of said error diffusion processing. comprising:

• analysis means for examining density values of a first density component and a second density component among said plural density components;
• and
• control means for exclusively or independently outputting the result of said error diffusion processing on said first density component and that of said error diffusion processing on said second density component, in accordance with a result of analysis by said analysis means,
• wherein if at least one of said first and second density components has an intermediate density value, said control means independently outputs the results of said error diffusion processing, while if said first and second density components do not have an intermediate density value, exclusively outputs the results of said error diffusion processing,
• wherein said plural density components of said multivalued image data are respectively converted by said error diffusion processing into N-ary codes.

An image processing method for performing error diffusion processing on multivalued image data having plural density components and outputting a result of said error diffusion processing, comprising:

• an analysis step performed by a host device of examining density values of a first density component and a second density component among said plural density components;
• and
• a control step of exclusively or independently outputting the result of said error diffusion processing on said first density component and that of said error diffusion processing on said second density component, in accordance with a result of analysis at said analysis step,
• wherein at said control step, if at least one of said first and second density components has an intermediate density value, the results of said error diffusion processing are independently outputted, while if said first and second density components do not have an intermediate density value, the results of said error diffusion processing are exclusively outputted, and
• wherein said analysis step includes:
• a first comparison step of comparing a sum of the density values of said first and second density components among said plural density components with a predetermined threshold value;
• and
• a second comparison step of comparing the density value of said first density component and the density value of said second density component with each other,
• wherein at said control step, printing is performed by said error diffusion processing based on said first density component or said second density component, based on results of comparison at said first and second comparison steps.

An image processing method for performing error diffusion processing on multivalued image data having plural density components and outputting a result of said error diffusion processing, comprising:

• an analysis step performed by a host device of examining density values of a first density component and a second density component among said plural density components;
• and
• a control step of exclusively or independently outputting the result of said error diffusion processing on said first density component and that of said error diffusion processing on said second density component, in accordance with a result of analysis at said analysis step,
• wherein at said control step, if at least one of said first and second density components has an intermediate density value, the results of said error diffusion processing are independently outputted, while if said first and second density components do not have an intermediate density value, the results of said error diffusion processing are exclusively outputted,
• wherein said plural density components of said multivalued image data are respectively converted by said error diffusion processing into N-ary codes.