高度自动化获取书籍扫描图像畸变参数的实验

分析了利用打印直线获取书籍扫描图像畸变校正所用参数时影响精度的一些因素,并提出了相应的措施。利用Visual C++6.0编写了自动获取畸变参数的程序。对不同的垂直扫描线用不同的灰度阈值进行图像分割,得到打印直线的扫描图像上各点坐标的测量值。为提高计算速度,对畸变参数进行了估计。在估计值附近,利用网格搜索法,计算畸变参数取不同值时各点坐标的理论值。根据最小二乘法原理,当各点坐标的理论值与测量值之差的平方和最小时,所对应的一组畸变参数即为最佳解。将打印有直线的纸张裹在已知直径的圆柱体上,在不同条件下扫描图像,用所编程序自动计算畸变参数,证明了这种方法的可行性。

Experilnent of high alltomatic deteFininatioll of distortion parameters for scanned book image

Several factors affecting the precision of distortion parameters that are determined by making use of printed line for correcting scanned book image distortion are analyzed,and corresponding measures to reduce their effect are presented.Using Visual C++ 6.0,a program for determining the parameters automatically is developed.On each vertical scanning line,different gray threshold is chosen to do image segmentation for obtaining experimental coordinates of every point on the scanned image of printed line.To increase the speed of calculation, the values of these parameters in advance are estimated.The theoretical coordinates of every point are calculated by the grid search technique that make these parameters take different values around their estimated values.According to the principle of the least-square method,when the sum of every squared difference between the theoretical and experimental coordinates gets to the smallest,the corresponding group of parameters is the best.In experiment,the printed line wrapping around diameter-measured cylinders is used to scan images under different conditions,then the program is used to determine distortion parameters,the feasibility of this method is certified.