Abstract: In a threshold matrix generation method, after periodic areas are set in a matrix space and elements existing every other one in a row direction and a column direction in each periodic area is set as target elements, performed is a step of assigning threshold values ranging from one on the most highlight side to a predetermined switching threshold value sequentially to target elements in the periodic areas. Assuming that elements to which threshold values are assigned are regarded as determined elements, in the step, under a condition that the number of determined elements is almost same in the periodic areas and each determined element is positioned in a vicinity of any one determined element in each periodic area, a target element whose distance to all determined elements is largest is specified within the periodic areas and a threshold value is assigned to the target element.

Abstract: In a printing apparatus, a colorimeter is provided for performing imaging calibration on an inline scanner for inspecting a printed image. During a printing operation, the inline scanner captures a test pattern image formed on paper and thereby obtains calibration imaging data, the colorimeter performs color measurement on the test pattern image and thereby obtains calibration colorimetric data, both data are used to update a correction factor LUT for imaging calibration, and the correction factor LUT is used to perform imaging calibration on the inline scanner.

Abstract: In a printing apparatus, a colorimeter is provided for performing imaging calibration on an inline scanner for inspecting a printed image. During a printing operation, the inline scanner captures a test pattern image formed on paper and thereby obtains calibration imaging data, the colorimeter performs color measurement on the test pattern image and thereby obtains calibration colorimetric data, both data are used to update a correction factor LUT for imaging calibration, and the correction factor LUT is used to perform imaging calibration on the inline scanner.

Abstract: An inkjet printer includes an image-forming part, forming an auxiliary layer on a base material by ejecting droplets of auxiliary ink and forming an image on the auxiliary layer by ejecting droplets of image-forming ink, the auxiliary ink changing a dot formation state of droplets of the image-forming ink. In a storage part, a reference table that associates each of a plurality of types of base materials with a proper dot area rate to be used when forming the auxiliary layer is stored. In a dot-area-rate determination part, a dot area rate to be used when forming the auxiliary layer on a target base material is determined as an auxiliary ink dot area rate by referencing the reference table using the type of the target base material. This enables the inkjet printer to form a highly precise image on various base materials.

Abstract: An inkjet printer includes an image-forming part, forming an auxiliary layer on a base material by ejecting droplets of auxiliary ink and forming an image on the auxiliary layer by ejecting droplets of image-forming ink, the auxiliary ink changing a dot formation state of droplets of the image-forming ink. In a storage part, a reference table that associates each of a plurality of types of base materials with a proper dot area rate to be used when forming the auxiliary layer is stored. In a dot-area-rate determination part, a dot area rate to be used when forming the auxiliary layer on a target base material is determined as an auxiliary ink dot area rate by referencing the reference table using the type of the target base material. This enables the inkjet printer to form a highly precise image on various base materials.

Abstract: An ejection part (3) in an inkjet printer (1) has ejection mechanisms (31a to 31d) for ejecting fine droplets of colored ink and an ejection mechanism (32) for ejecting fine droplets of clear ink, and a colored image is formed on a colored image print area of print medium (9) by the ejection mechanisms (31a to 31d). By the ejection mechanism (32), the colored image on the print medium (9) is coated with the clear ink and a code image is formed on a blank area around the colored image print area. In the inkjet printer (1), since the coating of the colored image and the forming of the code image are performed with the same clear ink ejected from the one ejection mechanism (32), improvement of wear resistance and improvement of security of the colored image can be achieved while reducing manufacturing cost of the apparatus of the inkjet printer (1).

Abstract: Color values Lab (1) are converted into corrected tone values YMCK (2) using a second table 22 in a printer profile P2. Next, these tone values YMCK (2) are converted back into color values Lab (2) using a first table 21 in the printer profile P2. Then, the color values Lab (1) before the conversion and the color values Lab (2) after the conversion are compared and differences therebetween are determined. Based on these differences, data of the second table 22 in the printer profile P2 is corrected. The above operation is carried out again using the corrected second table 22. By correcting the second table repeatedly, the accuracy of the second table 22 may be improved further.

Abstract: A method of changing a halftone dot area is provided. The method includes: performing an expansion process on rasterized binary halftone image data to generate multi-level halftone image data; processing the expanded halftone image data using an averaging mask to convert the expanded halftone image data into multi-level halftone image data having intermediate gradation levels; performing a gradation conversion on the multi-level halftone image data having the intermediate gradation levels based on a predetermined tone curve to perform a spreading/shrinking process for changing a density in an edge portion of a halftone dot; and performing an error diffusion process based on the corrected gradation to represent gradation in the form of small dots having densities corresponding to original gradation levels, thereby generating halftone data for proof in which the halftone dot area is changed in accordance with the output characteristic of an output device.

Abstract: A CPU 20 assumes a virtual color monitor in which actual chromaticity coordinates of colors expressed by fluorescent materials are replaced by virtual chromaticity coordinates having the same hues as those of the actual chromaticity coordinates but higher saturations than those of the actual chromaticity coordinates. The CPU 20 converts colorimetric values X, Y, and Z into luminance-linear values r′, g′, and b′ for red, green, and blue, based on a relationship of color conversion for the virtual color monitor at step S23. The CPU 20 then sets any one of the values r′, g′, and b′ to L at step S24 and compares the value L with i at step S26, where i is the &ggr;-th power of j and greater than 0. In case that the value L is less than i, the CPU 20 calculates a value c based on the remaining values other than the value L among the values r′, g′, and b′ at step S27.

Abstract: The present invention relates to an image reader 3 which reads the reflected light obtained by lightening from underneath a transparency board 6 on which an image original is placed, especially a cover 30 for the image reader 3 for adjusting the bend of the image original. The cover 30 comprise a vacuum pump (not shown) for reducing the air pressure in the space formed by the transparency board 6 and a bend member 48 and an airtight member 50. Therefore the image reader 3 utilizing the cover 30 can correctly read image on both a transparency original and a reflection original, and yet be easy to manipulate when reading the reflection original.