Image-processing apparatus, an image-forming apparatus, and a program
First Claim
Patent Images
1. An image-processing apparatus for quantizing multi-level (M-level) image data into N values, where M>
- N>
1, using a multi-level error-diffusion process or a minimum-average multi-level error method, comprising;
means for outputting correction data in which an error diffused from already-quantized pixels therearound is added to the multi-level image data of a pixel in question;
means for setting a quantization-threshold value based on the multi-level image data of the pixel in question;
means for comparing the correction data and the quantization-threshold value so as to output N-level image data;
and means for calculating an error generated when generating the N-level image data;
wherein, assuming quantized values are 0, 1, 2, . . . , N−
1, and tones of the quantized values are V0, V1, V2, . . . , VN−
1, respectively at least one threshold value Tha+1 in an interval between Va and Va+1 (where 0≦
a<
N−
1) of at least one input value, when an input tone value is ν
, is set based on equation (1), where the equation (1) is;
Tha+1=(√
{square root over ( )}((ν
−
Va)(Va+1−
Va)/2)))+Va.
1 Assignment
0 Petitions
Accused Products
Abstract
An image-processing apparatus for quantizing multi-level (M-level) image data into N-level values, where M>N>1, using a multi-level error-diffusion process or a minimum-average multi-level error method is disclosed.
The image-processing apparatus includes: means for outputting correction data; means for setting a quantization-threshold value; means for comparing the correction data and the quantization-threshold value so as to output N-level image data; and means for calculating an error generated with generating the N-level image data.
-
Citations
20 Claims
-
1. An image-processing apparatus for quantizing multi-level (M-level) image data into N values, where M>
- N>
1, using a multi-level error-diffusion process or a minimum-average multi-level error method, comprising;means for outputting correction data in which an error diffused from already-quantized pixels therearound is added to the multi-level image data of a pixel in question; means for setting a quantization-threshold value based on the multi-level image data of the pixel in question; means for comparing the correction data and the quantization-threshold value so as to output N-level image data; and means for calculating an error generated when generating the N-level image data; wherein, assuming quantized values are 0, 1, 2, . . . , N−
1, and tones of the quantized values are V0, V1, V2, . . . , VN−
1, respectively at least one threshold value Tha+1 in an interval between Va and Va+1 (where 0≦
a<
N−
1) of at least one input value, when an input tone value is ν
, is set based on equation (1), where the equation (1) is;
Tha+1=(√
{square root over ( )}((ν
−
Va)(Va+1−
Va)/2)))+Va. - View Dependent Claims (2, 3, 4, 5, 6)
- N>
-
7. An image-forming apparatus for quantizing input multi-level (M-level) image data into N values, where M>
- N>
1, using a multi-level error-diffusion process or a minimum-average multi-level error method and forming an image using dots which correspond to each of the N values, comprising;means for outputting correction data in which an error diffused from already-quantized pixels therearound is added to the multi-level image data of a pixel in question; means for setting a quantization-threshold value based on the multi-level image data of the pixel in question; means for comparing the correction data and the quantization-threshold value so as to output N-level image data; and means for calculating an error generated when generating the N-level image data; wherein, assuming quantized values are 0, 1, 2, N−
1, and tones of the quantized values are V0, V1, V2, . . . , VN−
1, respectively at least one threshold value Tha+1 in an interval between Va and Va+1 (where 0≦
a<
N−
1) of at least one input value, when an input tone value is ν
, is set based on equation (1), where the equation (1) is;
Tha+1=(√
{square root over ( )}((ν
−
Va)(Va+1−
Va)/2)))+Va. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
- N>
-
19. A computer-readable medium storing a computer-executable program for causing a computer to execute a process of quantizing multi-level (M-level) image data into N values, where M>
- N>
1, using a multi-level error-diffusion process or a minimum-average multi-level error method, comprising;a code for a step of outputting correction data in which an error diffused from already-quantized pixels therearound is added to the multi-level image data of a pixel in question; a code for a step of setting a quantization-threshold value based on the multi-level image data of the pixel in question; a code for a step of comparing the correction data and the quantization-threshold value so as to output N-level image data; and a code for a step of calculating an error generated when generating the N-level image data, wherein, assuming quantized values are 0, 1, 2, . . . . N−
1, and tones of the quantized values are V0, V1, V2, . . . , VN−
1, respectively at least one threshold value Tha+1 in an interval between Va and Va+1 (where 0≦
a<
N−
1) of at least one input value, when an input tone value is set to be ν
, is set based on equation (1), where the equation (1) is;
Tha+1=(√
{square root over ( )}((ν
−
Va)(Va+1−
Va)/2)))+Va. - View Dependent Claims (20)
- N>
Specification