1. A thermal image sensor comprising at least: one pixel matrix, wherein each pixel comprises at least one bolometer and means of applying a voltage to the terminals of the bolometer, and a comparator connecting an output of the pixel matrix to an input of the means of applying the voltage to the terminals of the bolometer of each pixel, wherein said comparator is capable of making a comparison between the output signal of the pixel matrix and a reference value, wherein the value of the voltage at the terminals of the bolometer of each pixel is determined at least partially depending on the result of the comparison.