A method of image processing for sampling the concentration of each portion of an image in the unit of a picture element and for binarizing the concentrations of picture elements in the unit of a submatrix of predetermined size to obtain a bi-level image, being characterized in that the bi-level image is obtained from the concentrations having been sampled according to the steps as follows: (a) calculating the average of the concentrations of the picture elements at every submatrix to which the picture elements belong; (b) determining the number of elements in the submatrix to be treated as either one of black and white according to a predetermined relation with the average; (c) assigning elements in the submatrix as the elements to be treated as either one of black and white up to the number determined in the step (b) in the predetermined order of the concentration of each element.

An ink jet image transfer lithographic apparatus is coupled to a source for supplying graphics and textual material to an ink jet printhead. The ink jet printhead melts a hydrophobic solid ink and sprays the ink onto a lithographic plate in a predetermined pattern. The solid ink solidifies upon contact with the plate. The plate is then mounted in a lithographic press for lithographic printing. As an alternative, the ink jet printhead may be mounted in a lithographic press for imaging a lithographic plate mounted in the lithographic press or for spraying ink directly onto the plate cylinder of the press. A succession of lithographic plates may be provided around the plate cylinder of the lithographic press and each plate discarded after use, leaving a clean plate on the plate cylinder.

Selecting proper half-tone screen systems for use with raster scanned images ensures the absence of Moire effects when using two or more color separations. Mathematical analysis provides an ensemble of screen patterns which are based on an odd/even relationship between the number of screen "lines" per repeat cell distance for combinations of screens. From this ensemble a critical selection is made of suitable screen parameters for the chosen font(s) using computer integration over repeat cell areas to show which chosen screens give invariance of white fraction with off-set distance in the two directions (horizontal and vertical). This comparison is carried out between all pairs of the required number of screens to be used.

An ink jet plate maker and proofer apparatus (66) and method adapted for printing a proof of a work to be printed, and making a printing plate (16) for printing the work, including a first element (68) including circuitry (70) controllably operable for generating ink drops of a first predetermined volume for printing the proof on a proofing receiver, and a second element (86) including circuitry (88) controllably operable for generating liquid drops of a second predetermined volume for image wise making or completing the printing plate (16), the second predetermined volume being different from the first predetermined volume. According to an exemplary embodiment, the apparatus includes a first print head (82) connected in fluid communication with a source of ink (106) for printing the proof of the work, and a second print head (92) in fluid communication with a source of a liquid (108) for making the printing plate, the print heads (82, 92) being disposed for ejecting drops of the ink and the liquid for making the printing plate onto a proofing receiver and a treated plate, respectively, positionable on a platen (96) relatively moveable with respect to the print heads (82, 92). The first element (68) is connected in electrical communication with the first print head (82) and includes a first clock (72) connected to a signal generator (76) operable for producing a drive signal for generating the ink drops of the first predetermined volume for printing the proof on the proofing receiver. The second element (86) includes a second clock (90) connected to the signal generator (76) and operable in conjunction therewith for driving the second print head (92) for generating the liquid drops for making the printing plate (16).

Described herein is an automated quality inspection station for evaluating color component characteristics of a product. The inspection station includes a color video camera, for capturing video frames of product images, and a control system for analyzing those video frames. The control system is programmed to perform a reference calibration and then a sample calibration. During the reference calibration an operator identifies component type areas from a displayed reference frame of a typical product assortment. The control system calculates color value density curves from the identified areas. The density curves are then calibrated to each other by scaling each of the density curves by a scaling factor. The scaling factors can either be provided directly by the operator or default values can be calculated by the control system. Default scaling factor values are calculated by summing the product of the corresponding density curve and an overall histogram of a sample video frame over a range of color values. Individual pixels are classified as one of a plurality of component types according to the highest calibrated density curve at the pixels' color value.