Abstract: The background compensation circuit defines a background threshold signal in dependence on an average value between the positive-peak and negative-peak signals previously received from the elements for scanning the pixels of the image, and in dependence on the analog signal (AS) of the pixel added to a reference signal. The circuit comprises two detectors (21, 22) for respectively detecting a positive peak and a negative peak and which each have a short charge time constant and a long discharge time constant. A summing circuit (25) generates a threshold signal (V.sub.s) as a linear combination of the signals (V.sub.max, V.sub.min) of the detectors (21, 22) the analog signal (AS) of the pixel and a reference signal (V.sub.r). Finally the threshold signal is compared (26) to the analog signal (AS) of the pixel to produce a binary reading signal which is at "one" level when the threshold signal is greater than the analog signal and is at "zero" level when the threshold signal is less than the analog signal.

Abstract: The apparatus for reading and digital processing of color images comprises groups of CCD sensing elements for reading the individual pixels forming the image. Each group of the sensing elements is associated with one primary color, for generating corresponding reading signals, which control a color indication circuit generating a color indicatory signal for indicating the presence of any color in the image. The colour indicator signal is derived from a table of zones of colours which is recorded in a ROM and can be addressed by the reading signals of the various colours, input from corresponding reading elements via compensation circuits. The colour signal is capable of controlling second selective scanning of document for recording the reading signals for all the primary colours of the image. The ROM is also capable of providing an indication of the mixture of colours of each pixel, which is compared to a predetermined mask for the purposes of suppressing a particular mixture of colours from the recording.

Abstract: One-dimensional compression is effected by addressing a first ROM (62) with information in respect of the length and the type of run. One-dimensional decompression is effected by addressing with the compressed code, a second ROM, bearing the information in respect of the runs and the length of the code. That is provided by a shift register controlled by a logic unit capable of recognising a group of least significant bits, to permit additional shifting of the register, and addressing of the second ROM with a bit number less than the maximum length of the codes. For two-dimensional compression or decompression, there is provided a pair of RAMs for temporarily storing a reference line which, together with the current line, actuates a logic means (38), for controlling coding and decoding of the latter.

Abstract: The ink jet dot printer comprises a head mounted on a carriage movable along a platen supporting the paper and is formed by a plurality of tubes and piezoelectric transducer for ejecting the ink, which are supported by two parallel plates spaced from one another, between which a polymerizable resin is cast to form a single block. The tubes are aligned in a single row F--F' in a direction inclined with respect to the printing line, in such manner that the distance between the extreme tubes measured perpendicularly to the printing line is equal to the maximum height of the characters. On the outside of the front plate supporting the tubes there is fixed a thin plate bearing a row of nozzles, each of which is aligned with the corresponding ejector tube.