| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique for approximating image quality of output images one of which is obtained by executing halftone processing by an error diffusion method and the other is obtained by executing halftone processing by a dither method when these types of halftone processing are used for converting an input value to a ternary or higher output value. <P>SOLUTION: In halftone processing by a dither method, an input density value of an attention pixel is converted to an output value in four tones for every pixel which structures an input image on the basis of three threshold values, DT<SB POS="POST">S</SB>, DT<SB POS="POST">M</SB>, and DT<SB POS="POST">L</SB>, which correspond to the attention pixel, among other threshold values arranged in a dither matrix. These three threshold values, DT<SB POS="POST">S</SB>, DT<SB POS="POST">M</SB>, and DT<SB POS="POST">L</SB>, are adjusted so that an output image obtained by executing the halftone processing by the dither method on the input image is approximated to an output image obtained by executing halftone processing of an error diffusion method on the same input image. <P>COPYRIGHT: (C)2013,JPO&INPIT |
