The present invention provides an image contrast enhancement method, which respectively calculates the absolute values of the differences of the gray scales between the pixels of two adjacent row of the same column and between the pixels of two adjacent column of the same row, and respectively calculates the first gray scale value weight and the second gray scale value weight according to the absolute values. Then, the cumulative calculation and the normalization process are performed according to the first, the second gray scale value weights. Ultimately, the enhancement gray scale table is obtained for redistributing the gray scale values of the respective pixels, which can raise the contrast of the image, reduce the distortion of the image and optimize the display result.

An image processing apparatus stores a first dither pattern group that includes dither patterns each corresponding to a gradation value in a first range and formed by line screens in which widths of lines are increased with an increase in the gradation value, a second dither pattern group that includes dither patterns each corresponding to a gradation value in a second range higher than the gradation value in the first range, and formed by void dot screens in which number of dots is increased and void regions surrounded by the dots are decreased with an increase in the gradation value, and a third dither pattern group that includes dither patterns for switching from the line screen to the void dot screen, switching to the void dot screen being completed before a first reference gradation value at which an image defect occurs for received image data is reached.

The present invention provides an image contrast enhancement method, which respectively calculates the absolute values of the differences of the gray scales between the pixels of two adjacent row of the same column and between the pixels of two adjacent column of the same row, and respectively calculates the first gray scale value weight and the second gray scale value weight according to the absolute values. Then, the cumulative calculation and the normalization process are performed according to the first, the second gray scale value weights. Ultimately, the enhancement gray scale table is obtained for redistributing the gray scale values of the respective pixels, which can raise the contrast of the image, reduce the distortion of the image and optimize the display result.

An image processing apparatus receiving a pixel value of a multivalue image includes: an input noise generating section that generates a noise; a green noise generating section that generates a green noise from an output value of a binarized processed pixel; an adder section that adds an error integrated value, the green noise and the noise, to the pixel value of the target pixel; the threshold value processing section that binarizes the pixel value of the target pixel after adding the error integrated value, the green noise and the noise; a subtractor section that calculates an error value by calculating a difference between an output value of the binarized target pixel and the pixel value of the target pixel including the error integrated value and the noise; and an error integrating section that outputs the error integrated value by using the error value of the binarized processed pixel.

A method of printing authentication indicia by applying an at least amplitude-modulated halftone print in a detection zone to an object uses adjoining halftone cells, in each of which a halftone dot is printed from a matrix of printable halftone elements, individual tone values of the halftone print corresponding in each case to a halftone plane of a halftone mountain for a halftone dot. In this process, the assigned screen plane of the screen mountain is modified in the detection zone in a predetermined manner for a plurality of tone values of screen dots to be printed, so that a predetermined matrix image of the screen elements to be printed is assigned to it while the tone value of the print remains constant.

A data-bearing medium has an array of data-bearing elements. The array of data-bearing elements represents an array of bits. A certain number of the bits repeat within the array of bits. Positions of the bits in each row of the array of bits are circularly shifted from positions of the bits in an immediately preceding row.

An image processing apparatus has a data acquisition unit that acquires first multi-valued data for a first ink that is not black ink and second multi-valued data for a second ink that is black ink; a threshold value acquisition unit that acquires a threshold value from a threshold value matrix; an offsetting unit that offsets at least one of the threshold value and the second multi-valued data; and a generating unit that generates first quantized data for the first ink by comparing the first multi-valued data and the threshold value, and generate second quantized data for the second ink by comparing the second multi-valued data and the threshold value with offset by the offsetting unit. Dispersibility of dots printed at positions corresponding to threshold values from a minimum value to a predetermined value is higher than that corresponding to threshold values except from the minimum value to the predetermined value.

An inkjet printer implements a method for identifying values for parameters for pixels to be printed by the printer. The method uses thresholds in a stochastic screen with a set of functions for the parameter for each primary color supplied to the printheads in the printer to identify values for the parameters. The parameters can be, for example, a number of drops to print for a color, a size of the drops to eject to form a pixel, or the number of inkjets to operate to form the pixel.

An image processing device which generates a halftone image includes: an image size adjustment unit which adjusts a size of the input image; and a halftone processing unit which performs halftone processing on the input image size-adjusted to generate a halftone image, wherein: the image size adjustment unit adjusts the input image to a same size in two or more printing modes among the plurality of printing modes, and the input image of the same size is subjected to the halftone processing; the unit limits arrangement of dots constituting the halftone image to dot arrangeable places of a selected printing mode among the plurality of printing modes, and performs the halftone processing based on an error diffusion method using an error diffusion coefficient matrix according to the selected printing mode; and the functions performed by the image size adjustment unit and the halftone processing unit are achieved using a computer.

A method and a system for image compression are disclosed. An image is converted to a halftoned image. The one or more halftoned lines in the halftoned image comprise one or more pixels. A first transformed image is generated from the halftoned image based on shifting of the one or more pixels, associated with the one or more halftoned lines in the halftoned image, by a first value. A second transformed image is generated from the first transformed image based on shifting of the one or more pixels, associated with the one or more halftoned lines in the first transformed image, by a second value. Further, a compressed image is generated based on compression of the second transformed image. The compressed image is stored in a storage device. Another method and system for image conversion are disclosed that converts the compressed image back to the first transformed image.