Image processing method, image processing apparatus and image forming apparatus

An image data processing apparatus comprising;

• determining means for determining whether input image data supplied is a first image mode or second image mode;
• histogram forming means for forming a histogram indicating the frequency of occurrence of density levels for each of a plurality of color component signals, corresponding to the input image data;
• reference value calculating means for calculating a first reference value for density adjustment for the first image mode corresponding to the histogram formed by the histogram forming means;
• reference value converting means for converting the first reference value for the first image mode into a second reference value for the second image mode and outputting the second reference value;
• and
• density adjusting means for adjusting the density of the input image data by using the first reference value when the determining means determines that the input image data is the first image mode and using the second reference value output from the reference value converting means when the determining means determines that the input image data is the second image mode and then outputting output image data.

An image forming apparatus comprising;

• determining means for determining whether input image data supplied is a first image mode or second image mode;
• histogram forming means for forming a histogram indicating the frequency of occurrence of density levels for each of a plurality of color component signals corresponding to the input image data;
• reference value calculating means for calculating a first reference value for density adjustment for the first image mode, corresponding to the histogram formed by the histogram forming means;
• reference value converting means for converting the first reference value for the first image mode into a second reference value for the second image mode and outputting the second reference value;
• density adjusting means for adjusting the density of the input image data by using the first reference value when the determining means determines that the input image data is the first image mode and using the second reference value output from the reference value converting means when the determining means determines that the input image data is the second image mode and then outputting output image data;
• and
• image forming means for forming an image on an image recording medium corresponding to the output image data output from the density adjusting means.

An image data processing method comprising;

• determining step of determining whether input image data supplied is a color image mode or monochrome image mode;
• histogram forming step of forming a histogram indicating the frequency of occurrence of density levels for each of a plurality of color component signals corresponding to the input image data;
• reference value calculating step of calculating a first reference value for density adjustment for the color image mode corresponding to the histogram formed in the histogram forming step;
• reference value converting step of converting the first reference value for the color image mode into a second reference value for the monochrome image mode and outputting the second reference value;
• and
• density adjusting step of adjusting the density of the input image data by using the first reference value when it is determined in the determining step that the input image data is the color image mode and using the second reference value output in the reference value converting step when it is determined in the determining step that the input image data is the monochrome image mode and then outputting output image data.

An image data processing method comprising;

• determining step of determining whether input image data supplied is a first image mode or second image mode;
• histogram forming step of forming a histogram indicating the frequency of occurrence of density levels for each of a plurality of color component signals corresponding to the input image data;
• reference value calculating step of calculating a first reference value for density adjustment for the first image mode corresponding to the histogram formed in the histogram forming step;
• reference value converting step of converting the first reference value for the first image mode into a second reference value for the second image mode and outputting the second reference value;
• and
• density adjusting step of adjusting the density of the input image data by using the first reference value when it is determined in the determining step that the input image data is the first image mode and using the second reference value output in the reference value converting step when it is determined in the determining step that the input image data is the second image mode and then outputting output image data.

An image forming method comprising;

• determining step of determining whether input image data supplied is a first image mode or second image mode;
• histogram forming step of forming a histogram indicating the frequency of occurrence of density levels for each of a plurality of color component signals corresponding to the input image data;
• reference value calculating step of calculating a first reference value for density adjustment for the first image mode corresponding to the histogram formed in the histogram forming step;
• reference value converting step of converting the first reference value for the first image mode into a second reference value for the second image mode and outputting the second reference value;
• density adjusting step of adjusting the density of the input image data by using the first reference value when it is determined in the determining step that the input image data is the first image mode and using the second reference value output in the reference value converting step when it is determined in the determining step that the input image data is the second image mode and then outputting output image data;
• and
• image forming step of forming an image on an image recording medium corresponding to the output image data output in the density adjusting step.