针对温度变化大的高温物体在CCD 相机上成像时图像会发白或发黑,导致图像中物体特征被弱化这一问题,提出一种基于灰度均值的彩色CCD 相机自动调光方法. 文中首先阐述了CCD 相机成像时物体热辐射对图像灰度的影响;然后分析了彩色CCD 相机采集的850 ~1200℃高温物体图像的特点,建立了RGB 基色图像灰度均值与积分时间的关系;最后提出一种自动调光方法,该方法通过采集一帧预测图像来计算物体所在的温度区间和最佳积分时间,根据最佳积分时间采集彩色图像,按照温度区间提取彩色图像对应的基色灰度图,并将其作为后续处理图像. 实验结果表明,该调光方法对温度变化具有很好的鲁棒性,基于此方法的彩色CCD 相机能采集到具有稳定灰度值的高温物体图像,有利于高温物体的几何测量和表面缺陷检测.

Due to the whitened or darkened CCD camera images of high-temperature objects with wide temperaturechange range, the object features in the images are weakened. In order to solve this problem, an automatic lightadjustment method based on average gray value for color CCD camera is proposed. In the investigation, first, theeffects of object heat radiation on the image gray during the imaging are discussed. Next, the image features of theobject with the temperature of 8501200℃are analyzed. Then, the relationship between the average gray of RGBprimary color images and the integral time is revealed. Finally, an automatic light adjustment method is constructed,which calculates the temperature zone and optimal integral time by using a prediction image frame, acquires thecolor image according to the optimal integral time, and extracts a proper primary gray image from the color imagebased on temperature zone for further usage. Experimental results show that the proposed method is robust to widetemperature change range and helps to acquire images with stable average gray value of high-temperature objects,which benefits the geometry measurement and surface defect detection of high-temperature objects.