1. A method, comprising: generating a plurality of scanlines of grayscale image data that represent an original document captured inside a scan area; interval sampling said captured grayscale image data to provide intensity values for corresponding pixels in said plurality of scanlines; creating a two-dimensional array of relative intensity values for said plurality of scanlines, with relative intensity values for pixels from a same scanline arranged in a same array row and relative intensity values for pixels from a same sampling interval arranged in a same array column; from said relative intensity values, identifying a plurality of background-to-medium transition points for said grayscale image data; and determining a skew angle of said original document based upon a location of a plurality of said background-to-medium transition points.