US 7,742,195 B2 · Image processing device, image processing method, and program product for the same

Abstract

An image printing process of the invention first specifies a pixel group tone value of each pixel group consisting of a preset number of multiple pixels and refers to one of correlation maps selected for the pixel group to convert the specified pixel group tone value to a multivalue code. Each of the correlation maps sets multivalue codes in correlation to pixel group tone values. The multivalue codes of all pixel groups constituting an image are output as control data to an image output device. The image output device determines the dot on-off state in respective pixels of each pixel group according to the received control data and actually creates dots on an output medium to complete an output image. Each correlation map referred to for the multivalue coding has a slightly lower tone resolution in a higher tone value area than in a lower tone value area. This arrangement desirably reduces the data volume of the control data, while preventing deterioration of the picture quality. The technique of the invention enables quick output of the control data and accordingly ensures high-speed output of a high-quality image by this simple procedure.

Claims23

Dependent claims

An image processing device that processes image data representing a multi-tone image by multivalue coding and outputs results of the multivalue coding, said image processing device comprising:

a pixel group tone value specification module that collects every preset number of multiple pixels to one pixel group to divide a large number of pixels constituting the image to plural pixel groups, and specifies a pixel group tone value as a representative tone value of each pixel group;
a correlation map storage module that stores in advance plural correlation maps, each correlation map setting a restricted number of multivalue codes obtained as results of the multivalue coding in correlation to pixel group tone values, where the restricted number of multivalue codes is less than a total number of possible states, one of which is selectively specified for each pixel group based on a preset number of threshold values provided corresponding to the preset number of multiple pixels included in the pixel group;
a multivalue coding module that selects one correlation map for each pixel group among the stored plural correlation maps and refers to the selected correlation map to convert the specified pixel group tone value of the pixel group to a multivalue code;
and
an output module that outputs multivalue codes of all the plural pixel groups.

2 more elements

An image processing method that processes image data representing a multi-tone image by multivalue coding and outputs results of the multivalue coding, said image processing method comprising:

Collecting every preset number of multiple pixels to one pixel group to divide a large number of pixels constituting the image to plural pixel groups, and specifying a pixel group tone value as a representative tone value of each pixel group;
storing in advance plural correlation maps, each correlation map setting a restricted number of multivalue codes obtained as results of the multivalue coding in correlation to pixel group tone values, where the restricted number of multivalue codes is less than a total number of possible states, one of which is selectively specified for each pixel group based on a preset number of threshold values provided corresponding to the preset number of multiple pixels included in the pixel group;
selecting one correlation map for each pixel group among the stored plural correlation maps;
and referring to the selected correlation map to convert the specified pixel group tone value of the pixel group to a multivalue code and outputting multivalue codes of all the plural pixel groups,
Wherein at least one operation of the image processing method is executed by a microprocessor.

2 more elements

A program product that causes a computer to attain an image processing method, said image processing method processing image data representing a multi-tone image by multivalue coding and outputting results of the multivalue coding,

said program product comprising:
a first program code of collecting every preset number of multiple pixels to one pixel group to divide a large number of pixels constituting the image to plural pixel groups, and specifying a pixel group tone value as a representative tone value of each pixel group;
a second program code of selecting one of plural correlation maps, which are stored in advance in a storage medium, for each pixel group, each correlation map setting a restricted number of multivalue codes obtained as results of the multivalue coding in correlation to pixel group tone values, where the restricted number of multivalue codes is less than a total number of possible states, one of which is selectively specified for each pixel group based on a preset number of threshold values provided corresponding to the preset number of multiple pixels included in the pixel group;
a third program code of referring to the selected correlation map to convert the specified pixel group tone value of the pixel group to a multivalue code and outputting multivalue codes of all the plural pixel groups;
and
a recording medium that records said first through third program codes therein.

3 more elements

Dependencies are inferred from the claim text.

Image processing device, image processing method, and program product for the same

Life of this patent

Image processing device, image processing method, and program product for the same

Life of this patent

Abstract

Claims23