Abstract: A method for producing a half-tone image faithfully representing a continuous-tne original includes a step of forming in the image a pattern of substantially continuous, substantially parallel lines at a frequency of between about 100 and 400 lines per inch, such that the width of the lines at a given point in the image varies in relation to the optical density of at least one color component at a corresponding point in the continuous-tone original. The method may be used for color separations with each separation produced by scanning at a different angle. The method may be implemented using photomechanical or electronic scanning techniques.

Abstract: A portable zoom camera obscura comprising: a telescopic structure including an inner tube and an outer tube positioned concentrically and slidingly movable relative to each other; a cover with a small, centered imaging hole attached to the imaging end of the outer tube; a semitransparent screen covering the inner end of the inner tube; a cover having a viewing hole and attached to the viewing end of the inner tube; and a diaphragm disk or ruler mounted on the imaging end, and including an aperture which can be positioned in a series of continuous overlapping positions with the imaging hole. The diaphragm disk or ruler also include lenses with different focal lengths, which, when positioned in front of the imaging hole allow the camera obscura to function as a photo-camera.

Abstract: A method for producing a half-tone image faithfully representing a continuous-tone original includes a step of forming in the image a pattern of substantially continuous, substantially parallel lines at a frequency of between about 100 and 400 lines per inch, such that the width of the lines at a given point in the image varies in relation to the optical density of at least one color component at a corresponding point in the continuous-tone original. The method may be used for color separations with each separation produced by scanning at a different angle. The method may be implemented using photomechanical or electronic scanning techniques.

Abstract: A method for producing a half-tone image faithfully representing a continuous-tone original includes a step of forming in the image a pattern of substantially continuous, substantially parallel lines at a frequency of between about 100 and 400 lines per inch, such that the width of the lines at a given point in the image varies in relation to the optical density of at least one color component at a corresponding point in the continous-tone original. The method may be used for color separations with each separation produced by scanning at a different angle. The method may be implemented using photomechanical or electronic scanning techniques.

Abstract: A method for producing a half-tone image faithfully representing a continuous-tone original includes a step of forming in the image a pattern of substantially continuous, substantially parallel lines at a frequency of between about 100 and 400 lines per inch, such that the width of the lines at a given point in the image varies in relation to the optical density of at least one color component at a corresponding point in the continuous-tone original. The method may be used for color separations with each separation produced by scanning at a different angle. The method may be implemented using photomechanical or electronic scanning techniques.

Abstract: The invention provides a device for offset and similar printing from a continuous tone original to produce a halftone image on a photosensitive layer comprising means for screening the information via a first array of parallely extending lines of effective minimum optical density and a second array of parallely extending lines of effective maximum optical density, the arrays being interposed to form a composite array of substantially parallel, spaced-apart, alternating lines of effective maximum and minimum optical density, the lines delimiting therebetween zones of effective graduated optical density, the gradient inside each zone progressively varying from low optical density adjacent lines of the first array to high optical density adjacent lines of the second array, the spacing of lines of the first array being between about 100 and 400 lines per inch and wherein the resulting thickness of each reproduced line on a resulting developed photosensitive layer, generated by screening the information via the ar

Abstract: A system for the development of exposed silver-halide films where the film moves emulsion-up on conveyor means, a viscous developer being applied to said film from a mechanism located above the moving film close to one end of the conveyor means, means being provided adjacent the other end to remove excess developer, means being provided for rinsing and fixing the developed film. The developer may be applied via a narrow slit at the bottom of a container, where the slit is essentially perpendicular to the direction of movement of the film. The uniformity of development layer may be attained by a roof-section above the moving film, the space being filled with developer.

Abstract: There is provided a developer for use in a one-step process for the development of exposed film resulting in an exposurewise pattern of silver particles which are large enough to be used as printing elements in ink-printing techniques, providing a wide range of densities in the developed film. The developer is based on a buffered system of a developing agent, a sulfinic acid salt of the type HO-R-SO.sub.2.M..times.H.sub.2 O where R is a hydrocarbyl group and M is a cation, and a formaldehyde source, with conventional adjuvants such as anti-fogging agents and the like. Instead of the sulfinic acid salt defined above there may be used any compound which upon dissociation in a aqueous medium results in the same active ionic species.