1. A method of de-skewing a digital image affected by perspective distortion, the method comprising: receiving a skewed input camera image affected by perspective distortion and containing curved lines of text; identifying text within the input camera image; determining a text direction of the lines of text to determine text direction lines including establishing a horizontal text direction based on calculation of a horizontal vanishing point and establishing a vertical text direction based on calculation of a vertical vanishing point; applying a three-dimensional de-skewing transformation of the text direction lines without reference to information from any other image; and applying a three-dimensional de-skewing transformation of the text direction lines without reference to information from any other image to straighten the curved lines of text and produce a de-skewed output image containing straight horizontal lines of text without perspective distortion.