Patent ID: 9189715
Filing Date: 2015-11-17
Classification: G06K,H04N

Abstract:
1. An image forming apparatus comprising: an image forming unit configured to print an image, based on a printing instruction; an input luminance range recognition unit configured to i) acquire input luminance information from multi-gradation monochrome image data in which a portion of an image range is selected, ii) generate a luminance histogram, and iii) determine, based on a minimum luminance value and a maximum luminance value of the luminance histogram, an input luminance range in which input luminance information of the image range is distributed; an output luminance range recognition unit configured to determine an output luminance range supported by the image forming unit; and a luminance range expansion unit configured to i) perform a mapping process for mapping input luminance information of pixels within the image range into the output luminance range, and ii) expand the input luminance range to a maximum luminance range to be dealt with by the image forming unit, wherein an after-expansion luminance value after the mapping process is calculated based in the following equation: wherein, min is minimum color value of the luminance histogram, max is a maximum color value of the luminance histogram, and N is the number of bits in which gradation expression in the image forming apparatus is available.