A method of determining the average density of a photographic original such as a transparency, including the steps of scanning the original in a raster pattern to produce a voltage varying electrical signal representing the point-to-point density or transmissivity of the original; clamping the voltage varying signal to a gray level; converting the voltage varying signal to a frequency varying signal having a frequency dependent on the variation of the voltage varying signal from the gray level; and counting the number of cycles of the frequency varying signal over a complete raster scan of the original to obtain a density signal representative of the average density or transmissivity of the photographic original. Apparatus is also disclosed for modifying the voltage varying signal in accordance with the density signal and for applying the modified signal to a flying spot cathode ray tube in order to make a reproduction of the photographic original on photosensitive material.

A method for pre-processing a picture signal prior to an operational circuit of a picture reproducing machine such as a color scanner and a color facsimile, wherein an original picture is scanned photoelectrically to obtain the picture signal, wherein first conversion characteristics data stored in a memory are read out by addressing addresses of the memory by the picture signal, and then are changed by second conversion characteristics data depending on a desired reproducible density range of the original picture.

The graphic information contained in the image is converted by means of a television camera to a video signal constituted by a succession of lines, each line being sampled sequentially so as to obtain an ordered series of points which is stored in memory. The method consists in selecting a parent point forming part of an isolated figure of the image. All the points in which the level of blackening on the image exceeds an adjustable threshold value are isolated automatically by marking with an automaton coupled with the memory. All the marked points corresponding to the figure are extracted from the memory and the figure is reconstituted from the points.

A method of transforming serial binary data exchanged between facsimile transceivers having different horizontal resolutions. Binary signal elements representing a scanning line are separated into a sequence of n bit data words and the number and type of subsequent bit changes within each data word is derermined. A conicident sequence of m bit data words is generated such that the bit pattern of each corresponding n bit data word substantially is reproduced by arbitrarily padding of an insignificant bit if n<m and by dropping of an insignificant bit, respectively if n>m; wherein n:m corresponds to the ratio of the transceiver resolutions. The serial data stream is reproduced from the sequence of said second data words and transmitted to the receiving facsimile transceiver for recording.

A method of information processing in which the sequence of points to be scanned on an original is selected, which sequence is freely selectable in both the coordinate directions. The original is scanned by scanning means producing electrical image signals. The image signals are digitalized. The information of the original is stored in the form of the image signals in the storage location of a memory. For a selected variation of at least part of the stored information the stored information is displayed. The addresses of the storage locations, which are intended to be varied in their information contents, are determined by detecting the coordinates of the part-information to be varied. The contents of the address storage locations is processed in a computer, which is supplied with control commands necessary for the intended variation of the information contents. The processed information is edited in a form suitable for the control of the production of the printing form.