7. The apparatus according to claim 6 , wherein the processor is configured to transform the digital image to a grayscale image prior to identifying the first pixels and the second pixels.
7. The apparatus according to claim 6 , wherein the processor is configured to transform the digital image to a grayscale image prior to identifying the first pixels and the second pixels. 8. The apparatus according to claim 7 , wherein each of the first pixels is lighter than a left neighboring pixel by a specified threshold and darker than a right neighboring pixel by the specified threshold, and wherein each of the second pixels is darker than a left neighboring pixel by the specified threshold and lighter than a right neighboring pixel by the specified threshold.