Patent ID: 8427704

Claim:
An image forming apparatus comprising: an image forming unit configured to form an image based on input multi-value pixel data formed by using an input data value or output multi-value pixel data formed by using an output data value; a status conversion unit configured to convert the input multi-value pixel data into status values based on an achromatic threshold and a maximum color threshold, wherein each of the status values corresponds to one of at least three kinds of status values comprising an achromatic status value, a maximum color status value, and a halftone status value; plural reference look-up tables each indicating an association between an arrangement of the status values of the pixels in a pixel window, and an output data value for forming the output multi-value pixel data, the pixels arranged in the pixel window corresponding to the status values which are converted by the status conversion unit from the input multi-value pixel data, and the pixels including at least a target pixel and a number of adjacent pixels provided on both sides of the target pixel; a first reference look-up table determining unit configured to determine a target reference look-up table from among the plural reference look-up tables, by using a table including a column of a three pixel arrangement, a column of pixel arrangement descriptions and a column of reference look-up table identifiers and based on the arrangement of the status values of the target pixel and the adjacent pixels in the pixel window, the pixel window comprising three pixels in a main scanning direction and one or more pixels in a sub scanning direction; and an output data generating unit configured to change the input data value of the input multi-value pixel data, into the output data value of the target reference look-up table determined by the first reference look-up table determining unit to form the output multi-value pixel data, and to output the output multi-value pixel data to the image forming unit.