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Image processing apparatus, image processing method, and program

  • US 20100129004A1
  • Filed: 11/10/2009
  • Published: 05/27/2010
  • Est. Priority Date: 11/27/2008
  • Status: Active Grant
First Claim
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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, whereinthe 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.

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