Apparatus for producing unevenness correction data
 A correction data production apparatus includes a detecting unit for reading a test pattern formed by a recording head having a plurality of recording elements constituting an array, and for detecting a density distribution of a range of the array of the plurality of recording elements, a corresponding unit for causing the density distribution detected by the detecting unit to correspond to the plurality of recording elements on the basis of a reference position where a density of an end portion of the density distribution reaches a predetermined threshold value, a production unit for producing correction data for an image formation density uniforming drive conditions in correspondence with the plurality of recording elements on the basis of the density distribution corresponded by the corresponding unit, and a changing unit for changing the threshold value in accordance with characteristics of the test pattern. 
Canon Kabushiki Kaisha
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B41J H04N B41J B41J B41J B41J B41J B41J H04N B41J B41J B41J
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Nobuyuki Hisashi Nobuhiko Masami Akio Yasushi Eiichi Haruhiko Toshimitsu Yoshihiro Haruhiko
Watanabe Fukushima Takekoshi Izumizaki Suzuki Miura Takagi Moriguchi Danzuka Takada Takahashi