Agfa Gevaert Nv

Pierre H Nys

Leon L Vermeulen

Paul W Vinck

Francois Leon Schelfaut

Hans Josephus Corluy

Raoul Jan Bortels

Rudy F Soetens

Louis N Carleer

Andreas Von Erdmannsdorff

A measuring strip for evaluating the quality of photographic half tone images which contains on a transparent base a test field (F) divided into at least two sub-fields, wherein (1) a first sub-field (F.sub.1) contains a plurality of individual areas each containing a group of opaque dots, wherein each individual area has dots of substantially equal size uniformly distributed in a transparent background area, and wherein (2) a second sub-field (F.sub.2) contains a plurality of individual areas each containing a group of transparent dots of substantially equal size uniformly distributed in an opaque background area, and wherein in each individual area containing (opaque or transparent) dots having substantially the same dot size the dots are at substantially equal distance from each other measured center-to-center and the dots are graduated in size in the areas of each said sub-field so that an area containing dots of smaller size contains more dots than an area containing dots of larger size, and wherein the light transmission of said first and second sub-field expressed as a percentage is different by at least 10%.

Measuring strip

A method for dot-size correction or modification in half-tone colour separations to be used in the production of printing plates for printing reproductions of coloured originals in which a contact print is overexposed through a photographic mask constituted so as to isolate a selected area in addition to being exposed normally for obtaining an exact copy of an original half-tone separation. The mask is generated electronically using an electrical signal obtained by scanning each separation, digitizing each signal and storing the digital values in a digital storage device. A halftone separation is visualized electronically as an image in a dislay device, e.g., video tube, an area of said image is defined for isolation and correction and the combination of positive and/or negative separations required to serve as a mask effective for isolating the selected area for purposes of dot evaluation is determined via a look-up table. The mask is visualized on the display device, evaluated for correctness, the isolation area is re-defined visually, and a new combination of separations to effectively mask the re-defined area is determined and evaluated. The resultant mask is reproduced photographically and used to identify the needed degree of dot correction. It is then also used to generate a dot-corrected photographic print by subjecting print material for said print to two photographic exposures, one being the normal exposure to reproduce the corresponding halftone separation and the other being an overexposure through the combination of the photographic mask and the corresponding separation for a dose to give the needed change in dot size.

Method for colour correction by dry dot etching using photographically

Process for the production of a photographic mask for tonal correction by dry dot etching wherein the selection of a particular halftone color separation image or overlaying registering combination of halftone color separation images used in a known process of mask production is not determined on the basis of the subjective attribute of color, i.e., hue, those areas to be color corrected, but is determined on the basis of optical density differences in at least one such halftone color separation, i.e., differences in contrast, between each area to be isolated as a substantially transparent area, and at least one particular background area surrounding each area to be isolated. The density differences can be compared between individual isolated areas and associated background areas directly or as the algebraic sums of such differences for a plurality of such areas. The calculation of the density differences and their comparison can be carried out by a computer.

Process for the production of photographic masks

Method for the photographic production of a document by simultaneously photographically copying a continuous tone image and a graphic data pattern with a single common exposure source, characterized in that continuous tone image is exposed to said light source and the thereby image-wise modulated light image is projected through a screen dividing the light-image in dots of varying size onto one area of a photographic material, and the graphic data is simultaneously exposed to said light source and the thereby pattern-wise modulated light is projected through a screen dividing the original halftone pattern in dots of substantially same size printing them within a dot percentage range of 50 to 99%.

Photographic method for the production of documents

A process for developing photographic silver halide lith-materials in an automatic processing machine with a lith-developer, wherein two replenishers are used, one for compensation of the developer exhaustion resulting from aerial oxidation and a second replenisher serving for the compensation of exhaustion by development.

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Berchem, Belgium

Pierre H Nys