Inspection of circuit boards for unauthorized modifications

A system for detecting unauthorized modifications to circuit boards, the system comprising:

• an image acquisition system that is configured to take an image of a target circuit board to generate a target image and of a gold circuit board to generate a gold image, the gold circuit board being a known-good circuit board;
• and
• a computer comprising a processor and a memory, the memory storing instructions that when executed by the processor cause the computer to:
• locate a plurality of fiducial points on the target image and on the gold image;
• perform perspective transformation on the target image using the plurality of fiducial points on the target image for reference and on the gold image using the plurality of fiducial points on the gold image for reference;
• and
• after the perspective transformation of the target image and the gold image, identify an anomalous section of pixels of the target image, the anomalous section of pixels of the target image having intensities that are different from intensities of a corresponding section of pixels of the gold image.

A method of inspecting circuit boards for unauthorized modifications, the method comprising:

• locating fiducial points on a target image of target circuit board and on a gold image of a gold circuit board, the gold circuit board being a known-good circuit board;
• performing perspective transformation on the target image using the fiducial points on the target image for reference and on the gold image using the fiducial points on the gold image for reference;
• after performing perspective transformation on the target image and on the gold image, subtracting intensities of pixels of the target image from intensities of corresponding pixels of the gold image;
• and
• detecting an unauthorized modification to the target circuit board by identifying pixels of the target image and corresponding pixels of the gold image that have different intensities.