Method for image acquisition and conversion comprising: low-pass filtering an image by an acquisition lens, producing from said low-pass filtered image an up-sampled image with a first resolution with an up-sampling factor using a image sensor, converting said up-sampled image into a multi-level image with a second resolution lower than said first resolution with an image processing circuit wherein said converting depends on said low-pass filtering of said lens and on said up-sampling factor. Adapted to gigapixel sensors and convention image sensors.