Method for estimation of image defocus and defocus restoration

A digital imaging method for imaging an open book having a book binding, said method comprising:

• scanning the open book including a non-planar original object to produce first scanned image data at a first focal plane;
• scanning the open book including same said non-planar original object to produce at least second scanned image data at a second focal plane;
• said first scanned image data is different from said second scanned image data wherein a distance between said first focal plane and said second focal plane is a predetermined quantity;
• estimating an out-of-focus distance of said object from said first and said second scanned image data;
• determining local defocus distances at a plurality of pixel columns parallel to the book binding, said defocus distance being determined from at least one image feature obtainable from said first scanned image data and said second scanned image data;
• and,
• restoring said first and/or said second scanned image data by deblurring said image data using inverse filtering.

A printing apparatus for reproducing an image representation of a non-planar object, said apparatus comprising:

• a planar imaging platen;
• a scanner for scanning said non-planar object placed on the platen to produce a first scanned image at a first focal plane and a second scanned image at a second focal plane;
• said first and said second scanned image data containing at least one of geometric distortions, blurring defects and illumination variations;
• said first scanned image data is different from said second scanned image data wherein a distance between said first focal plane and said second focal plane is a predetermined quantity;
• a processor for calculating an out-of-focus distance of said object from said first and said second scanned image data;
• an image processor for determining local defocus distances at a plurality of pixel columns, said defocus distance being determined from at least one image feature obtainable from one of said first scanned image data and said second scanned image data;
• a digital processing station for restoring said first and said second scanned image data by deblurring said image data using said local defocus distances;
• and,
• printing said deblurred image data.