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Abstract

Level data on an output line (24) carrying the digitized output of a video camera and analog-to-digital converter (12) is processed by a combination circuit (10) to store in an acquisition memory (16) the results of a feature-identification or histogram operation. In a histogram operation, the memory locations of the acquistion memory (16) represent the bins into which the levels represented by the level data are sorted, and the contents of those locations indicate the number of picture elements whose levels fall in those bins. In feature identification, the contents of successive memory locations in the acquistion memory (16) contain the positions of those picture elements whose levels have a selected feature. Common circuitry performs both the histogram and feature-identification functions. To perform the histogram function, a counter (39), whose output provides the address for the acquisition memory (16), is operated to load the output of a look-up-table memory (22), which acts as an encoder to indicate the bin into which the level represented by the level signal belongs. An increment circuit (52) is then operated to read the contents of that location in the acquisition memory (16), increment it, and return the incremented value to the specified memory location. For feature identification, the contents of the look-up table (22) indicate whether the levels represented by the level signals have the selected features. A control circuit (30) monitors the output of the look-up-table memory and clocks the counter (39) whenever the selected feature is encountered. This changes the address for the random-access memory (16) to that of the next location in memory, and the increment circuit (52), which is incremented on the occurrence of every picture element to keep track of picture-element location, writes the position of the picture element having the selected feature into the next location in the random-access memory (16).

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