DETECTION OF CONTAMINANTS USING X-RAY IMAGING

摘要

An X-ray scanning apparatus for locating a contaminant in a product, the apparatus comprising: means for generating an X-ray image of the product; means for assigning a grey scale value to a plurality of pixels; means for identifying a plurality of suspect pixels; means, which for each suspect pixel: selects two neighboring pixels in a first direction lying on opposed sides of the suspect pixel and determines which of the first direction pixels has the lowest grey value; selects two neighboring pixels in a second direction lying on opposed sides of the suspect pixel and determines which of the second direction pixels has the lowest grey value; determines a first direction difference value by taking the grey value difference between the lowest grey value first direction pixel and the grey value of the suspect; determines a second direction difference value by taking the grey value difference between the lowest grey value second direction pixel and the grey value of the suspect; determines a first direction score from the first direction difference value; determines a second direction score from the second direction difference value; compares said scores with a threshold value; and identifies the suspect pixel as representing a contaminant if said threshold value is exceeded.