A hidden information detector for image files extracts N least significant bits from each of a first set of pixels of an image file, wherein N is an integer greater than or equal to 1. The detector then applies a mask to each of the extracted N least significant bits to form a second set of pixel values and determines a first probability as to whether the second set of pixels encodes a hidden image. Responsive to the first probability exceeding a first threshold, the detector determines a second probability as to whether the second set of pixels matches an image encoded in the first set of pixels. Responsive to a determination that the second probability is less than a second threshold, the detector performs a non-image classifier on the second set of pixels.