Abstract: An output scanner for recording an image on a radiation sensitive medium comprises an at least part cylindrical support which carries the medium in use, the medium facing radially inwardly. A scanning unit is positioned radially inwardly of the support and has a generator for generating a plurality of modulated radiation beams, the beams being modulated with respective image information, and a reflector for reflecting the two beams onto the medium at respective, different positions. Optics focus the beams onto the medium. Motors cause relative rotation and traverse movement between the scanning unit and the support about and along the axis of the support respectively.

Abstract: A system for separating alternately stacked first and second sheets (5,6) such as film plates and paper. The system comprises a first sheet holding device (8,9) for holding a first sheet (5) of the stack; an eccentric (2) for causing relative separation movement between a sheet held by the first sheet holding device and the remainder of the stack so that the held sheet is positioned spaced above the remainder of the stack, the first sheet holding device being laterally moveable to feed the separated first sheet to an exit (12). A second sheet removal device (14) is provided for laterally feeding a second sheet (6) from the stack to an exit in generally the same lateral direction as the first sheet.

Abstract: A method and apparatus for modifying an image defined by data representing the colour component content of each pixel of the image. The method comprises, for each colour component of each pixel,(a) generating unsharp (U) and sharp (S) data and performing an unsharp masking algorithm on the sharp and unsharp data to generate fringe data (F);(b) modifying the fringe data with a weighting function (.phi.) determined in accordance with the values of the sharp or unsharp data for all of the colour components of the pixel; and(c) combining the modified fringe data with the pixel data to generate modified pixel data.By applying a weighting function related to all the unsharp values for the pixel and hence to the input colour component content of the input signals of a particular sample area, the fringe amplitude is varied according to the colour of the region thereby enabling sharpening or smoothing to be appropriate to the part of the image e.g. sharpening hair and smoothing skin colours.

Abstract: Apparatus for feeding flexible sheet (2) onto an inwardly facing curved surface (6) of an imagesetter comprises a feed system (3,4,7,8) for feeding the sheet from an input side onto and along the surface towards an output side. The feed system is also adapted to exert a force in the plane of the sheet (2) to cause the sheet to flex into conformity with the surface (6) and to form a ridge near one side. A monitoring system (12) monitors for formation of the ridge as an indication that the sheet conforms to the curved surface.

Abstract: In a method of producing a digital half-tone representation of an original image, wherein the representation is constituted by an array of output cell values representing the colour content of pixels of the original image, cell values are determined for successive output cells, for which cell values have not previously been determined. An output cell value is generated with reference to an input cell value related to the colour content of a corresponding pixel in the original image, and any error values propagated from previous iterations. Where the output cell value satisfies a predetermined condition, the effective colour content of a neighbourhood of previously determined output cell values is determined by addressing a look-up table containing a single value for each neighbourhood. An error value constituted by the difference between the effective colour content and the corresponding input cell value is determined and propagated for use in subsequent iterations.

Abstract: A graphics display system comprises a monitor (5); a first frame store (1) for holding digital data defining the color content of an image to be displayed on the monitor; a second frame store (2) for holding an array of control data, there being a control data value corresponding to each pixel of the image in the first frame store; and a processor (6,10,3) to cause the monitor to display the image in the first frame store under control of the control data array. The processor (6,10,3) means is adapted to cause a moving contrast image to be mixed with the image from the first frame store (1) under control of the control data array.

Abstract: A method of generating an output device control signal having portions representing the content of pixels of an image including at least two types of image content, in which data defining the content of each pixel of the image at a lower, first resolution and a higher, second resolution are passed respectively through a pair of processing paths, one corresponding to each image content type. A binary control signal is generated from the first resolution data in the first path by applying a stochastic screen. The binary control signal resulting from the stochastic screen is adapted to conform with the data at the second resolution, and the output device control signal is generated by combining data from the two processing paths.

Abstract: A method and apparatus for viewing the effect of outputting on the output device an image represented by digital data defining the colour content of pixels of the image. The apparatus comprises a monitor; a store; and a processor to enable a portion of the image to be selected, and for generating and storing in the store data simulating the selected image portion as it would appear after screening by the output device. The monitor is responsive to the stored data to display the simulated, screened image portion.

Abstract: A method of generating a graphics pattern comprising digital data defining the color content of pixels of the pattern within a pattern area at a first, high resolution, comprises defining (step 21) the color content of "seed" pixels at selected positions within the pattern area which are to influence the resultant pattern. The remaining pixels at the first high resolution are considered as having undefined color content. Successively lower spatial resolution versions of the pattern area are generated in accordance with a predetermined algorithm which, when sufficient defined pixels exist in the next higher resolution version neighboring an undefined pixel, interpolates color data for the corresponding lower resolution pixel, until all pixels of a lower resolution version contain defined data (step 25).

Abstract: A method and apparatus for processing data representing an image in a first color space suitable for controlling a first image output device. The apparatus comprises a processor (11, 14, 17) for reversibly transforming the image into a perceptual color space defined by lightness, colorfulness and hue components, and for modifying the lightness, colorfulness and hue components of the image in accordance with a predetermined algorithm so that all colors in the image fall within the gamut of a second image output device; and a store for storing data defining the modified and unmodified lightness, colorfulness and hue components.

Abstract: A method of generating a representation of an image comprises scanning a film (2) carrying an image to which the film has been exposed to obtain signals (4,5,6) representing the color component content of the recorded image. During exposure of the image its appearance has been modified in accordance with a function characteristic of the film. The signals obtained are modified with a function (11,10,8) constituting the inverse of the film characteristic function to compensate.

Abstract: Image display apparatus comprises a display monitor; an image frame buffer for storing data defining the color content of pixels of an image; and a control system for selecting from the frame buffer for each pixel displayed on the monitor the appropriate pixel data from the frame buffer. The relationship between the monitor pixels and the frame buffer pixels is defined by a preselected composite linear function, wherein the control system determines the frame buffer pixels corresponding to the monitor pixels by applying the preselected composite linear function in a stepwise manner.

Abstract: The invention relates to scanning apparatus including a transparency support (12) and scanning means (3,4,5) for scanning a transparency (1) on the support to generate an electronic representation of an image defined by the transparency (1). The surface (24) of the support (12) which carries a transparency (1) in use has a surface profile with irregular undulations (25) such that any Newton's rings formed between the transparency (1) and the surface (24) of the support (12) cannot be resolved by the scanning means in use. Methods of producing the irregular undulations are also described.

Abstract: Image processing apparatus comprises an input device including an indicator and a surface over which the indicator is moved. A host determines the position of the indicator on the surface and also the force by which the indicator is placed onto the surface. Frame stores store digital data defining the color component content of an image. The host simulates an electronic paint brush carrying paint whose characteristics are determined at least in part in accordance with the force of the indicator on the surface.

Abstract: Electronic image generation apparatus includes a monitor, a colour data array for storing digital data defining the colour component content of pixels of an image, a control data array for storing control data for each display pixel, and a mixer connected to the control data array and the colour data array for generating display pixel data comprised of a combination of proportions of the data in the colour data stores and other colour data the proportions being in accordance with the control data. The monitor is responsive to the display pixel data. A camera views a region within which an indicator may be moved, and is connected to the control data array such that data relating to the appearance of the region is recorded in the control data array.

Abstract: A light deflecting device for use in a light scanner, comprises a deflector (4) and a dove prism (13) mounted together on a rotatable support (16). The support (16) rotates about a nominal axis (2) coaxial with an incident light beam direction (11). A beam is incident on the deflector (4) so as to be deflected through a fixed angle (.THETA.) relative to the nominal axis (2) independently of any angular movement of the support (16) about the nominal axis.

Abstract: Apparatus for use in calibrating a display system comprising digital-to-analogue converters (D.A.C) (11,12,13) for converting a digital colour control signal to analogue colour component signals which are suitable for controlling an electronic display. An analogue signal modifier modifies the signals from the D.A.C. The apparatus also comprises a switch (10) for connecting between the D.A.C. and the analogue signal modifier. The switch is operable in a first mode (52,54) to pass signals from the D.A.C. (11,12,13) directly to the analogue signal modifier or in a second mode (53) to pass analogue calibration colour component signals to the analogue signal modifier such that the appearance of the signals from the D.A.C. and the calibration signals can be visually compared on a screen (17) to determine whether any reproduction errors are in the D.A.C. (11,12,13) or in the signal modifier.

Abstract: A method and apparatus for interactively generating a profile for an electronic image creation tool. The apparatus comprises a monitor (30); an operator input device (5, 31) ; a store (22) for storing the profile of an electronic image creation tool; and a processing system (1,2). The processing system is adapted to display an initial form of profile on the monitor (30), the digitizing tablet being operated by an operator so as to position an indicator on the monitor display at a desired position relative to the display profile. The processing system (1,2) is adapted to determine one or both of the distance of the indicator position from a datum position and the direction of the indicator position relative to a datum direction, and to monitor the profile in accordance with a predetermined algorithum dependent on the determined distance and/or determined direction.

Abstract: Image processing apparatus comprises a color converter for converting an input value, defining the color component content of a pixel of an image, to an output value, the color converter being adapted to convert groups of input values to respective, common output values.

Abstract: Test equipment, for testing that an image processing apparatus is operating correctly, is coupled to the output port of the image processing apparatus. A predetermined group of signals corresponding to a portion of an image from the image processing apparatus is stored in a memory in the test equipment. The signals are then analysed either by an operator using a monitor or by electronic comparison of the signals with reference signals corresponding to the portion of the image, from a reference store.