Abstract: A method for smoothing retouch in electronic color image reproduction employs a coordinate pen used by the retoucher as a retouch brush, to identify image point coordinates within an image point area. The color values associated with the image point coordinates are changed as a function of the color values of the nearby image point coordinates. The size of the areas which have their color values changed is operator-selectable. The color values of the areas which are changed can be matched to the marginal values of the area, or may be replaced by a mean value of the color values within the area. By this means image contours may be flattened, and the effective noise in the image surfaces may be minimized.

Abstract: A method for converting digital chrominance signals of a cartesian color coordinate system into digital color signals and saturation signals of a polar color coordinate system and including a transformation circuit for the transformation from cartesian to polar coordinates.

Abstract: Apparatus for generating and controlling an electron gun in a vacuum envelope comprising, a cathode, means for controlling the temperature of the cathode to control its current emission, an auxiliary electrode with an aligned opening mounted adjacent to said cathode and with the electron beam from the cathode passing through said aligned opening, means for maintaining the voltage of said auxiliary electrode slightly more negative than said cathode, and an annular anode mounted in a spaced relationship from said cathode and said auxiliary electrode.

Abstract: A method for producing half-tone reproductions such as printing blocks or color separators of an original on a recording medium by means of a recording element using rotated screens having any screen angle and any screen line spacing and being formed of periodically repeated, adjacent screen grid elements comprising screen dots varying in size with the tone values of the original.The recording medium has co-ordinated with it an UV co-ordinate system directed in the line direction and an XY co-ordinate system turned through the screen angle, both co-ordinate systems being subdivided into areal elements from which picture half-tone dots to be produced are collated. Notwithstanding the screen angle, screen threshold values are associated with areal elements of a matrix of limited scanning pattern range which corresponds to at least one screen grid element of the screen which is to be recorded.

Abstract: A screen for reproducing continuous-tone pictures of the kind which has an orthogonal, equally spaced screen structure and which is rotated through 45.degree. from the direction of scanning. In this invention, the individual screen dots are split up into four parts by lines extending parallel and perpendicular to the direction of reproduction which pass through the centers of the screen dots, thus producing square part screen-configuration which, in two opposite corners, each contain covered segments which derive from two different screen dots. Prior to reproduction, one such screen-configuration is stored for each tonal value liable to occur and at the time of reproduction these are called up again for selected tonal values and reproduced under the control of the scanning process.

Abstract: A roller for drum scanners is described, consisting of a hollow cylindrical element which is arranged for rotation at its ends and provided with suction openings for reception of a record carrier or of an original. The cylindrical roller element is assembled from a plurality of individual elements which are held together by means of a rod which may be screwed to end lid members of the roller element and are also bonded to each other.

Abstract: A method and an apparatus are provided for contrast intensification in the reproduction of masters in the field of electronic image processing by engraving devices and scanners. In the image-point-wise, opto-electronic master scanning, two outer field signals are obtained in addition to the image signal by scanning a first outer field and a larger, second outer field. A first differential signal and a second differential signal are generated from the image signal and the outer field signals and a third differential signal is generated from the two outer field signals. The first differential signal is combined with at least one of the other two differential signals to form an auxiliary signal which is added to the first differential signal in order to obtain a correction signal. The correction signal is then superimposed on the image signal for the purpose of contrast intensification.

Abstract: A method for reproducing colored masters in four-color printing where a color reduction or removal (UCR) which differs between the gray area and the chromatic area of the master is utilized in the production of the color separations. In the gray area, a color reduction is done in which a gray balance is produced between the three chromatic printing ink signals Y, M and C. In the chromatic area of the master, a color reduction matched to the respective maximum mean and minimum value of the three chromatic printing ink signals Y, M and C is accomplished.

Abstract: Method for producing a printing form by means of scanning a master and the recording surfaces in accord with a scanning raster or, respectively, a conforming recording raster upon employment of a random generator for the distribution of smallest points which are still printable to each raster field of the recording surface, whereby the plurality of said points which are still printable determines the respective tonal value and each raster field at the original side is resolved by means of fine-scanning into surface elements and the elements of approximately identical tonal value are combined to form sub-surfaces. Each raster field at the recording side is composed of surface elements and sub-surfaces, whereby the surface elements of the sub-surfaces at the recording side receive tonal values corresponding in terms of statistical mean, in that the sub-surfaces on the recording side, statistically distributed, are filled with a corresponding plurality of smallest points still printable.

Abstract: The invention relates to a method for partial electronic retouch in color image reproduction. The color values of the individual color components gained by means of image point-wise, trichromatic color image scanning and digitization are deposited in a storage medium (1). The image point coordinates of the color values to be retouched in a correction area (brush surface) displaceable across the color image and the plurality of correction steps per image point are simultaneously determined with the coordinate pen (51) of a coordinate identification device (50; 51; 52) which is employed by the retoucher like a retouch brush. Image point-wise allocated correction values are calculated for the marked correction area. The color values of the color image or of a color separation are read out of the storage medium (1) and are changed by the correction values under visual control on a monitor (2) in accord with the desired retouch effect.

Abstract: A light pick-up device for transparency and/or opaque scanning in either a drum or flat bed scanning device consists of a hollow body, which exhibits a light entry opening for the modulated light coming from the master. The inside surface of the hollow body, which is designed as a light pick-up surface for the opto-electronic conversion of the scanning light into an image signal, consists of a multitude of sub-surfaces, whose surface normals are oriented in the direction of the incoming scanning light. The sub-surfaces are the light surfaces of either opto-electronic transducers or are the end faces of optical fibers whose other end faces are coupled to an opto-electronic transducer. Because the disruptive influence of scratches and shadow edges in the master is suppressed, a high efficiency and a good uniformity of the scanning are achieved with the light pick-up device.

Abstract: In printing form production with electron beams, the imaging scale of the electron source on the source of the printing form is modulated gradation-dependent for engraving different cup geometries. The power density distribution in the effective point of the electron beam can then be approximately rectangular for all gradations. In particular, engraving the small cups, which was hitherto a vertical factor, is thus stable.

Abstract: The invention relates to a method and to a circuit arrangement for the partial recorrection of color recognition spaces in color recognition. Before the color recognition, the color coordinates (color locations) of characteristic sample points are determined in the colors to be recognized and sample color numbers are allocated to them, said sample color numbers being deposited in a color recognition memory. All color numbers of the remaining color locations of the color space are determined from the sample color numbers and are likewise stored. The respective color locations or, respectively, memory locations occupied with the same color numbers form a color recognition space within the color space. For subsequent boundary correction of a color recognition space, at least one auxiliary color sample is taken from a color to be recognized in the area of the desired change and the necessary sample color number is allocated to it.

Abstract: A light pick-up device for transparency and/or opaque scanning in a drum or flat bed scanning device consisting of a hollow body which has a light entry opening and at least one opening forming the light pick-up surface. That part of the inside surface which is opposite the light pick-up surface is a diffusedly reflecting reflector and the remaining part may be a mirror or also a diffusedly reflecting reflector. The light modulated from the master is collected in the light pick-up device, is reflected into the light pick-up surface, and is conducted from there to an opto-electronic transducer means which generates the image signal. Since the device suppresses the disruptive influence of scratches and shadow edges in the master, a high efficiency and high uniformity of the scanning are achieved with the light pick-up device.

Abstract: In engraving of printing forms particularly of gravure cylinders, it has previously been possible to produce run-free color raster configurations for only two colors. The present invention discloses rastering methods for run-free color production of four color impressions and polychromatic impressions.

Abstract: In a method and a circuit for determining a contour-defining angle formed by a contour in an image within a relatively small region thereof with a predetermined direction, the steps include selecting the region so that said contour passes as closely as possible through a center thereof, and subdividing the region into a number of sectors of substantially equal areas distributed substantially symmetrically about its center, and separated from one another by respective separation lines, the number being an even number and at least four, and one of the separation lines coinciding with the predetermined direction, obtaining brightness signals from each of the sectors in dependence of the proportion of the dark-to-light areas extending over each respective sector, generating difference signals from respective oppositely disposed sectors, processing the difference signals so as to identify the sector in which the transition from the light area to the dark area occurs, and determining by further processing the conto

Abstract: Refined recording of line contours in electronic reproduction technology, whereby the recording takes place by means of several selectively drivable recording beams within a raster point with finer resolution than the scanning. The control signals for the individual beams are obtained from the density values of the surroundings of the raster point to be recorded which are stored during the scanning.

Abstract: The present invention relates to a method and to elements for the execution of the method for the inspection of the reproduction quality of drawing elements which are exposed by means of a cathode ray tube on light-sensitive photo material. A simple and feasible development of the quality control of exposed photo material or other printing masters produced in this manner is achieved. The inspection ensues in that additional raster points are exposed which behave differently in response to different exposure and development conditions.

Abstract: An apparatus and a method for the recognition of colors on a colored image illuminated with a light source of a known spectrum composition, wherein the intensities of three primary colors are measured opto-electronically as color components, which represent the spatial co-ordinates of the color locations in a color space. Prior to color recognition the color components of at least one characteristic test point in each color or color region, which is to be recognized, are measured and noted. The test color components represent the corresponding test color locations in the color space. An identification symbol is assigned to each color component triplet of the test points and noted too.

Abstract: Positional errors are corrected for a light beam which is deflected point and line-wise across a scanning surface by a polyhedral rotating mirror. For each mirror surface, the positional errors are measured in the line direction and perpendicular thereto at a plurality of measuring points oriented in the line direction in the area of the scanning surface. Correction values are generated which, during simultaneous error measurement, are changed until the positional errors are compensated by means of correction elements. The determined correction values are stored and are read out for continuous correction during the actual operation synchronously with the mirror surfaces simultaneously located in the beam path. Light deflectors are employed as correction elements.