Halftone image screening array of parallel lines with effective maximum and minimum optical density and method of generating a halftone image utilizing the screening array

A method for generating a halftone image from a continuous tone original comprising exposing a commercial lith or line film to a continuous tone original via a device comprising means for screening information from said continuous tone original via a first array of parallelly extending lines of effective minimum optical density and a second array of parallelly extending lines of effective maximum optical density, said arrays being interposed to form a composite array of substantially parallel, spaced-apart, alternating lines of effective maximum and minimum optical density, said lines delimiting therebetween zones of effective graduated optical density, the gradient inside each zone progressively varying from low optical density adjacent lines of said first array to high optical density adjacent lines of said second array and the spacing of lines of said first array being about 100 to 400 lines per inch, wherein the resulting thickness of each resulting line generated on said exposed lith or line film as a result of said screening via said composite array continuously varies as a function of the density of each information point of the original.

A method for generating a halftone image from a continuous tone original comprising electronically outputting the information of the original onto an unexposed scanner type film in the absence of a standard photomechanical screen in an electronic output simulating a screen format, the pattern of this screen being a first array of parallelly extending lines of effective minimum optical density and a second array of parallelly extending lines of effective maximum optical density, said arrays being interposed to form a composite array of substantially parallel, spaced-apart, alternating lines of effective maximum and minimum optical density, said lines delimiting therebetween zones of effective graduated optical density, the gradient inside each zone progressively varying from low optical density adjacent lines of said first array to high optical density adjacent lines of said second array and the spacing of lines of said first array being about 100 to 400 lines per inch, wherein the resulting thickness of each resulting line generated on said exposed scanner type film as a result of said electrical output continuously varies as a function of the density of each information point of the original.

A method for generating a halftone image from a continuous tone original comprising outputting the information of the original onto an unexposed scanner-type film, in an electronic output simulating a screen format, the pattern of this screen being 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, said arrays being interposed to form a composite array of substantially parallel, spaced-apart, alternating lines of effective maximum and minimum optical density, said lines delimiting therebetween zones of effective graduated optical density, the gradient inside each zone progressively varying from low optical density adjacent lines of said first array to high optical density adjacent lines of said second array, the spacing of lines of said first array being between about 400-600 lines per inch and developing in a lith developer containing a hydroquinone developing agent in combination with carbonate, bicarbonate and halide salt together with sodium formaldehyde sulfoxylate and formaldehyde wherein a resulting thickness of each resulting line generated on said scanner type film continuously varies as a function of each information point of the original, but does not decrease in the Dmin region beyond 5 microns width even when the generated line becomes segmented.