Method for determining the profile of a bound document with structured light

Claim 1

In a scanning apparatus having an image acquisition system for recording images and a light stripe projector for projecting a light stripe, a method for determining a shape of the bound document positioned in an imaging area of the scanning apparatus, comprising the steps of: recording, with the image acquisition system, an image of the bound document having a light stripe projected thereacross by the light stripe projector, the image being defined by an array of scan lines, with each scan line having pixels with an intensity value; adaptively thresholding the pixels forming the image to identify pixels defining part of the light stripe, said adaptive thresholding step compensating for non-uniform illumination across the bound document recorded by the image acquisition system; identifying a pixel starting location that forms part of the light stripe on a first scan line near a midpoint of the image; tracking, from the pixel starting location, a first set of pixels that further define the light stripe in the image, the first set of pixels representing a trace of the light stripe projected across the bound document; smoothing the first set of pixels to minimize large transitions between scan lines; detecting a crease location along the first set of pixels that identifies a spine region of the bound document; and responsive to said detecting step, modifying the first set of pixels representing the trace, said modifying step replacing pixels near the crease location with a second set of pixels that are determined using a parametric model that approximates the spine region of the bound document.

Claim 20

A method for scanning a sequence of non-planar original images of a bound document, comprising the steps of: recording geometry data and raw image data for each image in the sequence of non-planar original images, said recording step including the steps of: projecting a light stripe on a non-planar original image, acquiring geometry data with an image acquisition system, and acquiring raw image data with the image acquisition system; and correcting the recorded raw image data for each image in the sequence of non-planar original images with the recorded geometry data, said correcting step performing, for each image in the sequence of non-planar original images, the steps of: identifying a pixel starting location that forms part of the light stripe on a scan line near a midpoint of the geometry data, tracking, from the pixel starting location, a set of pixels that further define the light stripe in the image, smoothing the set of pixels to minimize large transitions between scan lines, converting the set of pixels, which represent a trace of the light stripe projected across the bound document, to a page shape transform, and de-warping the recorded image data with the page shape transform to provide corrected image data.

Claim 21

A method for scanning a sequence of non-planar original images of a bound document, comprising the steps of: recording geometry data and raw image data for each image in the sequence of non-planar original images, said recording step including the steps of: projecting a light stripe on a non-planar original image, acquiring geometry data with an image acquisition system, and acquiring raw image data with the image acquisition system; and correcting the recorded raw image data for each image in the sequence of non-planar original images with the recorded geometry data, said correcting step performing, for each image in the sequence of non-planar original images, the steps of: identifying a pixel starting location that forms part of the light stripe on a scan line near a midpoint of the geometry data, tracking, from the pixel starting location, a set of pixels that further define the light stripe in the image, smoothing the set of pixels to minimize large transitions between scan lines, converting the set of pixels, which represent a trace of the light stripe projected across the bound document, to a page shape transform, and de-warping the recorded image data with the page shape transform to provide corrected image data.