Abstract: A self contained writing pad unit (1) comprises a pressure pad (7) for sensing movement of a writing instrument over a contact surface (2) of the unit when a user writes a sign, for example a signature, either directly on the contact surface or on a writing medium (4) supported by the contact surface. Electronics (8) including a RAM and timing systems determine data relating to the original signature. A power supply (9) is provided to enable operation of the electronics (8). The unit (1) is portable and the data represents dynamic characteristic features of the writing signature.

Abstract: This invention concerns a prepayment metering system using a card on which information may be stored and from which stored information may be erased. In one form, a number (A) recorded on the card is read at the meter and stored (30) in preparation for the next card insertion. To obtain a further credit at the meter, the card is taken to a terminal station (12) at which the number (A) recorded on the card is read and is subjected to an encryption process under the control of a key and the resulting number (A') is recorded on the card in place of the previous number (A). On the next insertion of the card at the meter (21), the number (A') is read from the card and subjected to a decryption step (22) using the same key, the result of the decryption being compared with the number stored in the register (30) and in the event of a match a credit is issued.

Abstract: This concerns retouching a set of n input image signals (1), one for each of the image printing colors, by converting these signals into a set of signals in a format (R, G, B) suitable for displaying the image on a monitor (3) to be viewed by an operator controlling the retouching. The converter (21) simulates the effect of the characteristics of the printing inks. In the present invention, for a rapid monitor response during retouching, the operator first generates, outside the main signal path from the image source to the monitor, a record (A) of n one-dimensional modifying functions corresponding respectively to the n printing colors. These printing-color modifying functions are converted into monitor-format modifying functions for storing in respective one-dimensional stores (B) in the said main signal path, where they modify the monitor-format image signals and therewith the displayed image.

Abstract: For register control when printing on a web, signals corresponding to a predetermined hidden pattern of low-amplitude density variations are superimposed on picture signals representing the image to be printed. After printing, light from elements of the printed image, with its hidden pattern, is detected by a register scanning head and the variations are correlated in a signal processor with the known variations of portions of the predetermined hidden pattern. In this way a position error signal is derived and can be used to correct the web position.

Abstract: In colored image reproduction, we have found that for the appearance of some self-colored objects (e.g. human flesh or plant leaves) to be satisfactory, when picture elements of the object are expressed in terms of luminance (L) and two chromaticity signals (CHR1 and CHR2), each chromaticity signal is a single-valued function of the luminance. In this specification, such objects are identified by means of a mask (24) or by a color recognition circuit or both and the corresponding area of the reproduction is made under the control of the luminance signal (L) for the picture elements of the object and two chromaticity signals generated by digital look-up tables (LUT2 and LUT3) having the luminance signal as an input and loaded with functions representing the respective functions relating chromaticity to luminance for that object.

Abstract: This specification discloses a method and means for color detection and modification wherein the recognition of color is based on the definition of a three-dimensional color sub-space within a three-dimensional color universe. Chromaticity values are digitized and modeled as a function of brightness or luminance. Three eight-bit words (each having 256 values) are stored for each pixel of a digitized color picture. The first value is an approximation of luminance, while the second and third values represent variations of chromaticity or chrominance. Over sixteen million combinations of color values are available for each of over one million pixels in a 1024.times.1024 pixel array image. Pattern recognition techniques are used to determine if a given color value lies within the three-dimensional color sub-space. Additional means and method are disclosed to modify or manipulate the color defined by the color sub-space.

Abstract: In the reproduction of colored images, the "white point", that is to say a point which determines which areas are to be printed with zero-ink, is a critical adjustment. In this invention, signals representing the three color components derived from the original are applied to a NAND gate (14) and when all of these signals simultaneously represent a zero printing color condition, the NAND gate generates a zero-ink signal. This is used to modify the zero-ink or white display on the monitor tube, for example by inhibiting passage of red and blue signals (18R, 18B) to the display tube while allowing the passage of green signals. The green signal to the monitor tube may be periodically interrupted, so that zero-ink areas are shown in pulsating green. The operator then adjusts the white point until the pulsating green areas correspond to the areas of the original which are to be reproduced with zero-ink.

Abstract: In image reproduction, a method of preventing the reproduction of a defect in an area (74) of the image, which has been indicated as including a defect-containing region, comprises comparing pixel values in a region (A.sub.o) of the said area outside the defect-containing region (72) to ascertain the range of the values of picture elements in a defect-free line or region in the neighborhood of the defect-containing region. Next image values for picture elements in a portion (A.sub.1) of the defect-containing region are compared with the said range of values to ascertain whether any such picture element has a value differing sharply from the said range of values.

Abstract: A color gravure printing press of simple construction which is easy to set up and operate, and is therefore economic for use in printing short runs comprises printing members (2) for at least two different colors arranged around a common printing cylinder (1), an impression cylinder (3) including means (11) to hold a sheet of substrate (15) to be printed, and at least as many inking assemblies (4) as there are different color printing members (2) arranged around the printing cylinder (1). Each of the inking assemblies (4) includes a doctor blade (35) movable towards and away from the printing cylinder (1). The press is arranged so that each inking assembly (4) applies ink only to its corresponding printing member (2) and each doctor blade (35) contacts only its corresponding printing member (2), and that the substrate (15) is held in a fixed position on the impression cylinder (3) until it has been contacted and printed by all of the different color printing members ( 2).

Abstract: A color scanner for the graphic arts of the kind in which three uncorrected color-component analogue signals from the scanner are converted into digital form and are applied to the inputs of a three-dimensional look-up table or read-only memory in which are stored corresponding color-corrected signal values for the three colors and, if desired, for black. Individual one-dimensional color-component look-up tables are interposed between the analogue-digital converter and the three-dimensional look-up table. The functions performed by the one-dimensional tables may include logarithmic conversion of the input signals, for example. Preferably, further individual one-dimensional look-up tables are inserted between the outputs of the three-dimensional table and a digital-analogue converter preceding an output scanner.

Abstract: To produce a whole page image from a number of separate images, the input images are separately scanned and reproduced at the required enlargement or reduction to produce pre-prints which are then assembled on a digitizer table in the relative positions required for the finished page; signals representing the boundaries of these positions are generated and stored; the boundary representing signals then control the derivation of output signals suitable for a scanner making the whole-page reproduction, each whole-page line signal including the line signals for each of the input images crossed by the page line, the output signals controlling the treatment of a sheet or surface for use in the preparation of a printed page.

Abstract: For presetting values of parameters in an image-reproducing process, an operator selects a spot on a transparency to be reproduced, for example by visual inspection of a projected image of an area of the transparency illuminated by a defocused light beam. The light beam is then temporarily brought to a focus on the selected spot and the light transmitted through the transparency on a photomultiplier, the signal from which is sampled within a very short period and held, after which the focused light beam is again defocused to enable the operator to select a further spot. The value of the sample signal is used in the presetting of the said parameter values. The period for which the focused light beam falls on the transparency is made small enough to avoid the bleaching of the transparency at the illuminated spot.

Abstract: In a method of image reproduction in which both pictures and test are to be combined in an image on a single sheet for use in the reproduction of a printed page, and in which the signals resulting from the scanning of the pictures are stored prior to the preparation of the sheet, a high resolution is achieved in the reproduction of the text without requiring excessive storage capacity for the picture signals by scanning the text at a resolution which is an integral multiple n of the picture resolution and, when the text and picture signals are merged to control an output scanner operating at the higher resolution, applying each line of picture signals extracted from store n successive times to the output scanner.

Abstract: In a method of preparing a screened reproduction, a laser beam modulated in an on-off manner scans a film or plate comprising a substrate resistant to the laser beam and a two-layer coating which is removed by the laser beam, after which correction is carried out by subjecting the image-defining coating dots to the action of a chemical agent. The coating layer adjacent the substrate is attacked by the chemical agent but the overlying coating layer is resistant to the chemical agent and protects the top surface of the first layer, permitting a reduction of the size of the coating dots without a reduction in their thickness.

Abstract: For the reproduction of colored originals, a set of standard color patches is scanned with an original to be reproduced and corresponding signals are applied to a display system having controls for adjusting the appearance of the displayed original and color patches. The standard color patch signals applied to the display are gated out and used to adjust a color-modifying means in the signal path between the input scanner and the output scanner, for reproducing the original, in such a manner that the standard color patches if reproduced by the output scanner would simulate the appearance of the displayed standard color patches after the adjustment of the display system.

Abstract: Apparatus for reproducing a half-tone image of an original comprises a support, preferably in the form of a cylinder, for a light-sensitive record medium, an exposing head for exposing a record medium on the support, and means preferably in the form of a mechanism for rotating the cylinder and a lead screw for moving the head axially of the cylinder, to produce a relative scanning motion between the exposing head and the record medium. The exposing head includes a row of side-by-side light modulators or light sources extending in a direction such that the areas illuminated by the modulators or sources on the record medium extend in a direction across the width of a scanning line on the record medium. The area of illumination of the record medium provided by each light modulator or source varies in the said direction and is of lower intensity at its ends than at its middle and each area overlaps the areas of illumination provided by adjacent modulators or sources.

Abstract: In the reproduction of a half-tone image, x and y pulse trains are generated in synchronism with the production of image-representing signals resulting from scanning the image to be reproduced; the x pulse train is multiplied in frequency by first and second factors and the y pulse train by third and fourth factors, all factors being irrational or nearly irrational and being different functions of the screen angle selected for printing; the first and third pulse trains are accumulated and combined and the second and fourth pulse trains are separately accumulated and combined, the resulting signals being applied to a function generator which produces a predetermined screen pattern signal which is a periodic two-dimensional function of the position of the scanned image element in the two mutually perpendicular directions.

Abstract: To provide an electronically reproduced image of an original in which defects have been removed by retouching, defects in the original are marked in such a manner that the signals from an analysing scanner corresponding to the defect marking are distinguishable from those corresponding to the remainder of the original and the sensing of the defect-representing signals is used to cause a replacement signal, derived as a function of the densities of picture elements adjacent the defect in the original, to be substituted for the defect-representing signal before the train of signals from the analysing scanner is used to control the treatment of an output surface to form the image.

Abstract: In a system for producing screened images, for each set of image-representing signals derived from one rotation of an input scanner cylinder, n sets of screen-representing densities are derived corresponding to screen densities of parallel tracks each of which has a width which is a fraction of the screen pitch. The set of image-representing signals for a line of the image is modified n successive times as a function of the n respective sets of screen-representing densities and each of the n sets of screen-modified image-representing signals is applied in turn to modulate a single output element in an output scanner in which the scanning beam scans the image-reproducing area at a pitch that is n times finer than that of the input scanner.