To eliminate image defects produced by high-energy particles passing through a time delay integration image sensor, upstream detection is effected on the digital values supplied by the pixels of the same rank that have successively observed the same scene point. This detection makes it possible to ignore or to correct values from corrupted pixels in establishing the digital signal representing the luminance of an observed scene point. Detection is based on the calculation of the difference between a first digital value pi,a(t1) and a second digital value pi,b(t2) supplied by two pixels Pxi,a and Pxi,b that have observed the same scene point, subtracting the second value from the first, and comparing it to a predetermined threshold k. If this difference is above the threshold, the first value is too high, the first value is ignored in the summation Σ′i effected to establish the luminance of the scene point, replacing this value with the second value to which it has been compared. Alternatively it is replaced by a mean value or excluded from the calculation.