Abstract: A method and apparatus for matching the print outputs of two printers having different characteristics. For the purpose of laser printing, or more generally for reproduction on any printing device with limited number of printing levels, a color or grayscale image has to be transformed into an array of printing decisions at each pixel of the output image. Sometimes this array is the only available representation of the original image. One may desire to print this array on a printer with different characteristics from the printer for which the array was originally prepared. The method and apparatus solve this problem by generating a printing decision matrix which takes into account the differences between the two printers.

Abstract: A computer system and method solve the problem of getting a useful three-dimensional representation of an object like the spine using a small amount of data. This is done by gathering three-dimensional data in the form of a set of 2D computer tomography (CT) slices of a patient's bones and a coaxial set of 2D CT scout images, which are digital two-dimensional X-ray images that can be produced by a CT scanner; extracting from each of these three-dimensional data sets a corresponding stack of 2D contours; and constructing a 3D geometric model of the object. The main features of spinal deformation are captured by integrating these two sets of three-dimensional data, and constructing from them a three-dimensional geometric model of the spine. Scouts are usually used to monitor CT scan acquisition. Here, they are also used as an essential source of data.

Abstract: A technique which combines the advantages of blue noise and clustering obtains more pleasant "blueish" effects in the rendering of the grey levels for which the original multicell mask generates unwanted periodic representations. Such original multicell clustered dither array patterns which are undesirable are replaced by less periodic ones while preserving all benefits of the classical methods, and in particular, leaving the nicest patterns unchanged. An automated process redistributes the locations of the threshold values corresponding to undesirable grey levels to obtain more pleasant "blueish" effects in the rendering of the grey levels.

Abstract: A computer system and method solve the problem of getting a useful three-dimensional representation of an object like the spine using a small amount of data. This is done by gathering and combining three-dimensional data in the form of (a) a set of 2D computer tomography (CT) slices of a patient's bones with (b) a set of 2D CT scout images, which are digital two-dimensional X-ray images that can be produced by a CT scanner. The main features of spinal deformation are captured by integrating these two sets of three-dimensional data, and constructing from them a three-dimensional geometric model of the spinal. Scouts are usually used to monitor CT scan acquisition. Here, they are also used as an essential source of data.

Abstract: A system and method to print grey scale or color images using fewer colors of ink than in the original image. This method distributes the error made at each point (due to the embodied approximation) to the neighbors of that point while obtaining some chosen predetermined patterns for several colors or grey levels. Getting these predetermined patterns and essentially predetermined patterns for all colors in turn reduces the anisotropic algorithmic artifacts, suppresses edge over-enhancement and allows for good performances on patches of uniform and almost uniform colors or grey levels.

Abstract: A printing method and apparatus takes into account the errors in the amount of black due to dot shape and size at the pixel where these errors occur, propagates corrections of these errors in order to preserve the logics of error diffusion, and permits a trade-off between completeness of the correction and computational time. The method and apparatus corrects for the actual shape of the printer dots in most error diffusion methods usable in digital halftoning.

Abstract: A computer system and method solve the problem of getting a useful three dimensional representation of an object like the spine using a small amount of data. This is done by gathering and combining three dimensional data in the form of computer tomography (CT) scans of a patient's bones with two dimensional data consisting of CT scout images (or scouts), which are digital two dimensional X-ray images that can be produced by a CT scanner. The main features of spinal deformation are captured by combining the two dimensional data from CT scouts and the three-dimensional information from the CT scans using simple modeling of vertebrae. Scouts are usually used to monitor CT scan acquisition. Here, they are also used as an essential source of data.

Abstract: A method and apparatus to calibrate a printer which do not depend on geometric assumptions on the printed dots. The method takes account of the fundamentally probabilistic nature of the process of printing any dot on some types of printers such as laser printers. It allows estimating the probability distribution of what gets printed at each pixel depending on the local configuration of dots to be printed in such a way that only a limited number of tests need to be done, while no artificial cutoff is introduced on the size of local configurations to be taken into account. The calibration method can be applied to many problems encountered in digital printing, and permits computing printer dependent calibration of a dithering method without need for further direct measurements.

Abstract: A technique combines most of the advantages of both blue noise and clustering in generating a clustered aperiodic mask and using it in a dither array algorithm for halftoning. The method of halftoning of grey scale images utilizes a pixel-by-pixel comparison of the image against a clustered aperiodic mask in which the clustered aperiodic mask is comprised of a partly random and partly deterministic single valued function which is designed to produce visually pleasing dot configurations when thresholded at any level of grey.