BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an ink-jet recording apparatus according to an embodiment of the present invention;
FIG. 2 is a block diagram showing a control device and a driving system in the ink-jet recording apparatus in FIG. 1;
FIG. 3 is a diagram showing a conveying direction of paper and movement of a carriage in FIG. 1;
FIG. 4A is a diagram showing a recording head in FIG. 1;
FIG. 4B is a diagram showing a recording head in FIG. 1;
FIG. 4C is a diagram showing a recording head in FIG. 1;
FIG. 5 is a diagram showing a conveying belt in FIG. 1;
FIG. 6 is a diagram showing a minimum unit pattern of a diagonal line base;
FIG. 7 is a diagram showing tones expressed in a conventional halftone process;
FIG. 8 is a diagram showing a size of a dither mask used in practice;
FIG. 9 is a diagram showing a threshold matrix used in a conventional halftone process;
FIG. 10 is a diagram showing characteristics of human sight;
FIG. 11 is a diagram showing a conventional dot arrangement between patterns of halftones in which diagonal line bases are emphasized;
FIG. 12 is a diagram showing a gradation pattern of line base dithering using a conventional halftone process;
FIG. 13 is a diagram showing overlapping of ink;
FIG. 14 is a flowchart showing a process in a host PC in response to an image recording request from a user;
FIG. 15 is a flowchart showing a process (recording process) in the ink-jet recording apparatus in FIG. 1 upon receiving print data from a host PC;
FIG. 16 is a flowchart showing a halftone process in FIG. 15;
FIG. 17 is a schematic diagram showing a growth pattern of a diagonal line base set in the halftone process in FIG. 7;
FIG. 18 is a schematic diagram showing a growth pattern of a diagonal line base set in a conventional halftone process;
FIG. 19 is a diagram showing images recorded in the recording process in FIG. 15;
FIG. 20 is a diagram showing images recorded in a conventional recording process;
FIG. 21 is a diagram showing a difference between an image recorded in the recording process of FIG. 15 and an image recorded in a conventional process;
FIG. 22 is a diagram showing size of dots (ink droplets) in a case of multiple values (N=four values);
FIG. 23 is a diagram showing growth of dots to become large droplets in each dot area in a case where a solid image is generated in N=four values in line dithering (⅕ base);
FIG. 24 is a diagram showing values of density of an original image;
FIG. 25 is a diagram showing numerical values in a matrix indicating the density of the original image shown in FIG. 24;
FIG. 26 is a diagram showing an example of a dither mask in a case of two values;
FIG. 27 is a diagram showing an output image through the dither mask of FIG. 26;
FIG. 28 is a diagram showing a dither mask for small droplets in a case of four values;
FIG. 29 is a diagram showing a dither mask for medium droplets in a case of four values;
FIG. 30 is a diagram showing a dither mask for large droplets in a case of four values;
FIG. 31 is a diagram showing an output image through the dither masks of FIGS. 28 to 30;
FIG. 32 is a diagram showing a dither mask obtained by employing the present invention;
FIG. 33 is a diagram showing an output image through the dither mask shown in FIG. 32;
FIG. 34 is a diagram showing a bayer dither mask;
FIG. 35 is a diagram showing how dots are placed through comparison with thresholds in FIG. 34;
FIG. 36 is a diagram showing an example of a growth pattern of dots in a case of four values in a bayer dither process;
FIG. 37 is a schematic diagram showing variations of a recording head;
FIG. 38 is a diagram showing a test pattern; and
FIG. 39 is a flowchart showing a halftone process in a case where an error diffusion method is used.
Patent Application
20070216953
