Apparatus for producing unevenness correction data

A correction data production apparatus comprising:

• designating means for designating a test pattern to be formed by a recording head, said recording head comprising a plurality of recording elements constituting an array, from a plurality of test patterns, each of said test patterns having a characteristic, so that said test patterns have different said characteristics from each other;
• reading means for reading the designated test pattern formed by said recording head;
• detecting means for detecting a density distribution of a range of said array of said plural recording elements;
• setting means for setting a threshold value corresponding to each of said test patterns, in accordance with the characteristic of each of said test patterns;
• conforming means for causing the density distribution detected by said detecting means to conform to said plurality of recording elements based on a reference position where a density of an end portion of the density distribution reaches the threshold value, said reference position being adjusted in accordance with the threshold value;
• and
• producing means for producing correction data for making uniform an image formation density in correspondence with said plurality of recording elements based on the density distribution corresponded by said conforming means.