Automated detection of creases and/or tears in scanned prints

A scanning apparatus, comprising:

• a scanner platen operable to support a document having a surface;
• an imaging device operable to perform operations comprises capturing images of a document having a surface, wherein in the capturing the imaging device is operable to perform operations comprising
• scanning across the document surface in a first scan direction in relation to orientation of the document multiple scan lines respectively illuminated from different illumination angles relative to the document surface, and
• scanning across the document surface in a second scan direction in relation to orientation of the document multiple scan lines respectively illuminated from different illumination angles relative to the document surface, the first and second scan directions being different;
• and
• a processor operable to perform operations comprising generating the captured images from scan line illumination reflected from the document surface during the scanning of respective ones of the scan lines across the document surface, and detecting defects in the document based on the captured images, wherein the detecting comprises detecting at least one of a crease or a tear in the document.

A scanning system, comprising:

• a scanner platen operable to support a document having a surface;
• an imaging device operable to perform operations comprises capturing two-dimensional images of the document, wherein the imaging device comprises two light sources that are operable to illuminate the document surface with respective scan lines from the different respective illumination angles, and in the capturing the imaging device is operable to perform operations comprising
• scanning across the document surface in a first scan direction in relation to orientation of the document multiple scan lines respectively illuminated from different illumination angles relative to the document surface, and
• scanning across the document surface in a second scan direction in relation to orientation of the document multiple scan lines respectively illuminated from different illumination angles relative to the document surface, the first and second scan directions being different;
• and
• at least one processor operable to perform operations comprising generating the captured images from scan line illumination reflected from the document surface during the scanning of respective ones of the scan lines across the document surface, and detecting defects in the document based on the captured images, wherein the detecting comprises detecting at least one of a crease or a tear in the document.

A non-volatile computer-readable storage medium comprising computer-readable program instructions, which when executed by a processor, causes the processor to perform operations comprising:

• calculating a first component of a surface normal vector at each pixel from a first set of images generated during scanning across a document surface in a first scan direction in relation to orientation of the document multiple scan lines respectively illuminated from different illumination angles relative to the document surface;
• calculating a second component of the surface normal vector at each pixel from a second set of images generated during scanning across the document surface in a second scan direction in relation to orientation of the document multiple scan lines respectively illuminated from different illumination angles relative to the document surface, the first and second scan directions being different;
• and
• registering the first and second sets of scanned images and to calculate a deviation of the surface normal vector at each pixel;
• and
• thresholding the deviation of the surface normal vector at each pixel so as to detect pixels associated with damaged regions, said detected pixels forming a bit mask.