Abstract: A halftone screen generator, halftone screen and a method for making the halftone screen are described. The halftone screen has a screen angle and rulings that define the theoretical centers of gravity of the halftone dots. The actual centers of gravity of the halftone dots are displaced from the theoretical centers of gravity by the length and angle of random phase vectors. In one example, the positional displacement of the centers of gravity of the dots is dot size dependent in an inverse relationship. The shift in dot centers of gravity away from the theoretical centers of gravity defined by the halftone screen effectively breaks up screen "patterning" and avoids objectionable halftone "graininess".

Abstract: Method of displaying (a) radiographic image(s). A method and apparatus for displaying radiographic image(s) is disclosed. The image is decomposed into detail images at multiple resolution levels and a residual image, detail images are then modified and together with the residual images subjected to a reconstruction process wherein modified detail images are only taken into account up to a displayable resolution level.

Abstract: A method for construction of a scaleable font database comprised of data stored in a compact form for retrieval in one of several usable forms common in digital typography. The method comprises the steps, for each text character of a font collection of: generating a digital representation of the character and identifying it with respect to character code and typeface design, determining segment endpoints and associations within a model of the character, measuring actual dimensions for the associations, and determining segment descriptors for each contour segment comprising the complete outline of the character.

Abstract: This invention relates to a novel dynamic collimator which can be adapted to a linear accelerator (LINAC). The collimator is such that the shape of the jaw arrangement, and therefore the collimated beam of X radiation from the LINAC, can be changed and conformed in a very flexible and versatile way. In a preferred embodiment of the invention, the collimator has three pairs of opposing, parallel jaws, each pair of jaws being moveable, under control, to open and close in variable amounts. Each set of pairs may be oriented at a 60.degree. orientation such that the open transmission area of the collimator has a hexagonal shape. Variations on this sixth jaw collimator, including larger numbers of jaws, also are included within the invention. The variety of shapes with such a variable hexagonal collimator is enormous. Irregular target volumes can be filled by beams of radiation that can be nested because of the hexagonal nature of the jaw configuration, giving it added conformal shaping capabilities.

Abstract: A method for making an image by means of a direct thermal imaging element, comprising on a support a thermosensitive layer incorporating an organic silver salt and a reducing agent contained in said thermosensitive layer and/or in other optional layers. The imaging element is imagewise heated by means of a thermal head having energizable heating elements. The activation of the heating elements is executed duty cycled pulsewise with the steps of preheating each heating element for a preheating time such that a preheat temperature in the imaging element is reached, which is just below the conversion temperature; selecting a pulse duty cycle such that a maximal density on the imaging element will be reached at the end of the maximal writing time; retrieving from a memory for each individual pixel an individual writing time related to a desired density on the imaging element; and energizing the heating elements with the selected pulse duty cycle for a time related to the retrieved individual writing time.

Abstract: A method and apparatus for storing scaleable font data in a compact form and retrieving it in one of several usable forms common in digital typography. The retrieval process can be influenced by parameters to produce not only the original typeface designs that were compressed, but also variations on those typeface designs. Variations produced in this manner are related typeface designs which therefore effectively add new fonts to the family originally stored. Individual character pixelmaps and scaleable character outlines are two of the forms which can be retrieved from the compressed font data. The storage and retrieval methods are designed so that the time needed to produce a single character pixelmap from the internal form is less than that required for producing the same pixelmap from an uncompressed hinted outline font stored in an industry-standard format.

Abstract: A contrast enhancing processing method is disclosed that is based on a transformation of an original image into a multiresolution edge representation based on a wavelet transform. The multiresolution edge representation is modified and subsequently subjected to a reconstruction procedure. Different embodiments are disclosed that are based on different forms of the multiresolution edge representation.

Abstract: A radiographic image read out system having on-line performance verification. A number of parameters to be used in a test program are stored together with (a) limiting value(s) for (a) characteristic value(s) resulting from application of the test program. An image signal of a phantom is processed according to the test program to determine at least one characteristic value. At least one limiting value for each determined characteristic value is retrieved from storage and a hard copy of the image of the phantom along with the at least one characteristic value in relation to the limiting value(s) is produced.

Abstract: A method and apparatus for finding the stored device independent coordinate triplet (CIEL*a*b*triplet) which is closest to the device-independent target color triplet and then looking up the coordinates in device-dependent ABC space which correspond to this best fit among the color patches. A set of new points is defined in ABC space about the best fit point. The raster for the selection of these points in ABC space is independent of the stored color patch points. The magnitude of the increments away from the best fit color patch can therefore be made as small or large as desired. Using this new set of points about the best fit color match, each point of this set is converted back into CIEL*a*b* space points by interpolation and each of these points is compared with the target color in CIEL*a*b* space and the point determined with the smallest difference thereto, .DELTA.E.

Abstract: A method for monitoring the sensitivity of a system that reads a radiation image or an irradiated object with the radiation image being stored in a photostimulable phosphor screen. The method employs the steps of scanning the screen with stimulating irradiation, detecting the light emitted upon stimulation, compressing the electric representation through square root amplification, and then digitizing the compressed electric representation. For a sensitivity class that was set when the radiation image was generated a corresponding expected noise variance value .sigma..sub.e.sup.2 is retrieved from a predefined table and the ratio .sigma..sub.y.sup.2 /.sigma..sub.e.sup.2 is calculated and thresholded. A warning is generated when the ratio exceeds a threshold value T.sub.+ or when the ratio is smaller than a threshold value T.

Abstract: A system for supplying a processed radiographic image to a remote device. The system is disclosed for supplying a radiographic image obtained by reading an exposed photostimulable phosphor screen that has been processed in a processing station to a remote device such as a display device that is connected with said processing station via a network and a distributed network filing system.

Abstract: A method is described for the rendering of an image on a carrier by a rendering system having a restricted density resolution. A classic screening method for a binary rendering technique is extrapolated to a plurality of energy levels that belong to three classes: non-marking, non-stable and marking stable energy levels. For each class, specific rules must be respected, in order to obtain predictable results without density discontinuities on the carrier. The methods make full use of the spatial and density resolution of the rendering system in areas of high density and increase the reproducibility of low densities by giving up some spatial resolution in the lower density regions.

Abstract: A system and method for reading and processing a radiation image that has been stored in a photostimulable phosphor screen. An identification station, a read out and processing station and an off-line workstation are provided. A customized and configurated parameter set is generated that links with an examination type a set of parameters. This parameter set is used when controlling operation of each individual station of the system.

Abstract: A universal radiation image identification system for use in an environment such as a hospital wherein an information management system is already available. The identification system is interfaced to the existing information system in order to avoid reentering the identification data with respect to radiological data. The radiological data or image typically is stored in a photostimulable phosphor screen.

Abstract: Multiple processing of radiographic images based on a pyramidal image decomposition.A method of multiple processing a digital representation of a radiographic image is disclosed that is based on a pyarmidal decomposition of said image. A pyramidal decomposition is stored and retrieved to be applied to at least two different processing cycles, processed images are obtained by application of a reconstruction algorithm.

Abstract: Method and apparatus for displaying images obtained by reading out stimulable phosphor screens wherein radiation images are stored. A mosaic type image is composed by means of a plurality of read-out images and said mosaic type image is displayed on a preview monitor or on one of a plurality of preview monitors.

Abstract: A method and apparatus for compensation for misregistration of printing plates in printing of polychromatic document pages or images, in which a trapping map image is superiraposed upon a structured graphic image representing the layout of a document page or image from which it is derived, so as to prevent light leaks and other errors at the boundaries between color regions within the image. The trapping map image is itself a structured graphic object to be included as the last object imaged in the data representing the original image. The geometrical description of this trapping map image is independent of specific trapping decisions applicable to the associated image. Instead, such decisions are controlled by means of a user interface providing options ranging from fully automatic to completely manual interactive operation.

Abstract: The disclosed methods for generating scatter-compensated radiation image are based on one irradiating shot of the object. By comparing the detected signal under a partially transparent body (ea. disk or strip), positioned between the x-ray source and the object being imaged, with the signal in the image near the border of the shadow of the partially transparent body, the radiation scatter signal in the location of the body is calculated. In case of a polychromatic source, calibration with two known materials allows accurate calculation of the radiation scatter. The partially transparent bodies are positioned at several locations in between object and source and, by means of interpolation technique, the radiation scatter in every location of interest can be calculated. The radiation scatter image is subtracted from the original image of the object.

Abstract: A beam scanner has a beam deflector mounted within a hollow shield having a beam entrance aperture and a beam exit aperture. The beam exit aperture is sealed by a window through which the deflected beam exits the hollow shield. A spin motor rotates the hollow shield, beam deflector and the window about a spin axis. A hydraulic system maintains the periphery of the window in an undistorted condition.

Abstract: A method of creating a histogram of an image signal matrix, representative of a radiographic image obtained by scanning a stimulable phosphor sheet carrying a radiation image with stimulating rays, detecting the light emitted after stimulation and converting the detected light into electrical image signals, is described wherein the histogram is created by capturing only a fraction of the image pixels comprised in the image signal matrix, this fraction being determined on the basis of statical pixel sampling.