带钢图像灰度补偿算法研究

Research on Algorithm of Grey Scale Compensation for Steel Strip Images

在应用CCD作为图像传感器进行带钢表面缺陷视觉检测时,经常由于现场条件限制或材料平面度误差的影响而无法得到理想效果的带钢图像。当用线阵CCD进行带钢表面缺陷检测时,往往由于传感器尺寸较大而镜头到带钢的距离有限,获得的带钢图像呈现出中间偏亮、两侧偏暗的成像效果。针对此类图像应用最小二乘法拟合二次曲线方程,得到曲线参数,并对带钢图像进行了灰度补偿,获得了较为满意的灰度均衡效果。

When CCD is used as the image sensor to detect steel strip＇ s surface defects, it is very often that no satisfactory image can be obtained for the field restriction and the error of the material＇ s surface smoothness. When the linear CCD was applied to the detection of the strip surface defects, because the size of the sensor was compara- tively larger and the distance between the sensor and the steel strip was limited, the image got by the sensor would be brighter in the middle and darker at both sides. For these images, a method using least-square principle fitting quad- tic curve was adopted and some curve parameters were obtained. In this way, the pixel grey scale was compensated and the experimental results were satisfactory.