Patent ID: 8208751
Filing Date: 2012-06-26
Classification: H04N

Abstract:
1. An image processing apparatus that quantizes multi-level (M-level) image data into N levels (M>N>2) using a multi-level error diffusion method or a multi-level average-error minimization method, the image processing apparatus comprising: a γ-conversion unit that performs γ-conversion on an integer part in a real number value after ideal gradation conversion that aims to obtain desired density or brightness; an area-gradation expressing unit that expresses a decimal part by area gradation, the decimal part being in the real number value after the ideal gradation conversion; an integerization unit that adds a value obtained through the γ-conversion and a value expressed by the area gradation to obtain an integerized value corresponding to a value of the ideal gradation conversion; a correction unit that adds a peripheral error to the integerized value to obtain a correction value; and a threshold setting unit that sets an N−1-type threshold value for a value corresponding to the value after the ideal gradation conversion, wherein the conversion to N levels is performed by using the correction value and the N−1-type threshold value, to thereby express the real number value after the ideal gradation conversion so that input multi-level (M-level) image data obtains the desired density or brightness.