Halftone Dot formation Method and Apparatus for Reducing Layer Thickness of Coloring Material Inside Halftone Dots, and Image Formation Apparatus

Abstract

An image processing method generates a halftone-dot image by forming a halftone dot, which is represented by a set of one or plural output dots and corresponds to an intensity of an input image signal, while making a part of the dots constituting the halftone dot to be an actual non-output dot so as to reduce an amount of a coloring material of the halftone-dot portion. When the intensity of the image signal exceeds a predetermined value and is in a predetermined range, while maintaining contour dots, which are output dots contribute to formation of a contour of the halftone dot, to be the output dot, the image processing method makes a part of dots inside the contour dots to be the actual non-output dot.

1 . An image processing apparatus for generating a halftone-dot image by forming a halftone dot, which is represented by a set of one or plural output dots and corresponds to an intensity of an input image signal, while making a part of the dots constituting the halftone dot to be an actual non-output dot so as to reduce an amount of a coloring material of the halftone-dot portion, the image processing apparatus comprising:
 a binarization processing section that, when the intensity of the image signal exceeds a predetermined value and is in a predetermined range, while maintaining contour dots, which are output dots contribute to formation of a contour of the halftone dot, to be the output dot, makes a part of dots inside the contour dots to be the actual non-output dot,   wherein the binarization processing section deals with a line-shaped halftone dot having a structure in which the halftone dot is continued in a line shape, in a range where the input image signal is equal to or larger than a predetermined density.   
     
     
         2 . The image processing apparatus according to  claim 1 , when making the part of dots inside the contour dots to be the actual non-output dot, the binarization processing section makes the non-output dot continue in the line-shaped halftone dot in a predetermined density range. 
     
     
         3 . The image processing apparatus according to  claim 1 , wherein when making the part of dots inside the contour dots to be the actual non-output dot, the binarization processing section maintains the non-output dots being isolated each other inside the line-shaped halftone dot.