A method and an apparatus suitable for screening a receptacle are provided. An image signal conveying an input image related to contents of the receptacle is received, the image signal having been produced by a device that is characterized by introducing distortion into the input image. A distortion correction process is applied to the image signal to remove at least part of the distortion from the input image, thereby to generate a corrected image signal conveying at least one corrected image. The corrected image signal is processed in combination with a plurality of data elements associated with a plurality of target objects in an attempt to detect a presence of at least one of the target objects in the receptacle. A detection signal is generated in response to detection of the presence of at least one target object in the receptacle.