A method for composing a global histogram of the values of the pixels of a hardcopy original includes a division of a detection area, which may be larger than the original, in stripes. For each of the stripes, a local histogram is made, which is added to a candidate histogram. If the decision is made from the values of the local histogram that a stripe belongs to the original, the candidate histogram is added to the global histogram. In this way, a representative histogram of the original is obtained, even if the white pixels from the original are indiscernible from the white pixels from the cover of the scanner. The method is embodied in an electronic component, including an application specific processing unit.