Projection profile analysis for skew angle estimation of woven fabric images

In this paper, a skew angle detection method based on projection profile analysis is introduced for woven fabric images. The horizontal or vertical projection profiles (VPPs) of woven fabrics tend to fluctuate in bigger magnitudes as the skewed image rotation approaches to the aligned position of the horizontal or vertical yarns in respect of the image edges. The image is rotated through a range of angles and horizontal or VPPs are computed at each angle. In order to detect the skew angle, difference values are computed from adjacent elements of projection profiles. Standard deviation of the difference values for each angle is used as a criterion of the tested skew angles. Experimental results show that the projection profile analysis is suitable for skew angle estimation of woven fabric images