Image forming apparatus and method of correcting the characteristic of each body by printing reference pattern in the machine and reading the printed pattern again

A color image forming apparatus which includes an input function of taking in color image data on a document by scanning and an output function of forming an image on the basis of the color image data, the color image forming apparatus comprising:

• means for generating a first color gradation pattern with a plurality of density areas;
• first formation means for correcting the first color gradation pattern on the basis of a first color correction data item previously stored to produce a second color gradation pattern and forming the second color gradation pattern on a first image medium by use of the output function;
• means for taking in the second color gradation pattern on the first image medium by use of the input function and generating a third color gradation pattern;
• means for creating a second color correction data item used to make a correction so that the density in each of a plurality of density areas of the third color gradation pattern may be essentially equal to the density in each of a plurality of density areas of the first color gradation pattern;
• means for combining the first color correction data item and the second color correction data item to produce a third color correction data item;
• and
• second formation means for correcting the image data entered by the input function on the basis of the third color correction data item and forming the corrected image data on a second image medium.

A method of correcting the gradation characteristic of an image forming apparatus which includes an input function of taking in image data on a document by scanning and an output function of forming an image on the basis of the image data, the method comprising:

• the step of generating a first gradation pattern with a plurality of density areas;
• a first formation step of correcting the first gradation pattern on the basis of a first correction data item previously stored to produce a second gradation pattern and forming the second gradation pattern on a first image medium by use of the output function;
• the step of taking in the second gradation pattern on the first image medium by use of the input function and outputting a third gradation pattern;
• a step of creating a second correction data item used to make a correction so that the density in each of a plurality of density areas of the third gradation pattern may be essentially equal to the density in each of a plurality of density areas of the first gradation pattern;
• and
• a combining step of combining the first correction data item and the second correction data item to generate a third correction data item.

A method of correcting the color gradation characteristic of a color image forming apparatus which includes an input function of taking in color image data on a document by scanning and an output function of forming an image on the basis of the color image data, the method comprising:

• a step of generating a first color gradation pattern with a plurality of density areas;
• a first formation step of correcting the first color gradation pattern on the basis of a first color correction data item previously stored to generate a second color gradation pattern and forming the second color gradation pattern on a first image medium by use of the output function;
• a step of taking in the second color gradation pattern on the first image medium by use of the input function and outputting a third color gradation pattern;
• a step of creating a second color correction data item used to make a correction so that the density in each of a plurality of density areas of the third color gradation pattern may be essentially equal to the density in each of a plurality of density areas of the first color gradation pattern;
• a step of combining the first color correction data item and the second color correction data item to produce a third color correction data item;
• and
• a second formation step of correcting the image data entered by the input function on the basis of the third color correction data item and forming the corrected image data on a second image medium.