Automatic correction of digital image distortion
AssigneeNuance Communications, Inc.
InventorsLászló Feró, Pál Solymosi, György Tamási
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Abstract
A method of de-skewing a digital image is described. An input camera image is initially received, and text within the input camera image is identified. A text direction of the identified text is determined to determine text lines within the camera image. A three-dimensional de-skewing transformation is determined of the text lines to make the text lines horizontal. Then the de-skewing transformation is applied to the input camera image to form a de-skewed output image. An unwarping transformation may also be applied to the input camera image for straightening text lines that are curved.
Claims6
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.
A computer program product in a non-transitory computer readable storage medium for de-skewing a digital image affected by perspective distortion, the product comprising:
- program code for receiving a skewed input camera image affected by perspective distortion and containing curved lines of text;
- program code for identifying text within the input camera image;
- program code for determining a text direction of the lines of text to determine text direction lines within the camera image 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;
- program code for applying a three-dimensional de-skewing transformation of the text direction lines without reference to information from any other image:
- and
- program code for 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.
Dependencies are inferred from the claim text.