Method of image acquisition by an image sensor of cmos type for the recognition of optically readable code

Abstract

The invention provides a method for acquiring an image of a target code, which allows the CMOS sensor, after the reader has been triggered to acquire a target code, to rapidly determine, and internally, a desirable exposure-time value Topt for the image capture of this code. When it is triggered, the sensor activates a measuring mode Mode_MES with a rapid acquisition of image data for k different exposure-time values Ti, i=1 to k, k being at least equal to 2, and this acquisition is employed only by the sensor and to rapidly define a desirable exposure-time value on the basis of histograms H(Ti) calculated with the image data acquired with the various exposure times; this value is stored in the register of image-capture parameters, and the sensor then activates a nominal image-acquiring mode Mode_ACQ, which applies this desirable exposure-time value delivered by the registered to all the pixels of the matrix array, and the obtained image DATA-OUT is the image delivered as output by the sensor, for recognition/decoding of the code by an external system.