成像环境因素对烟叶图像采集结果的影响及校正研究

The Influences of Imagery Environmental Factors on the Acquisition of Flue-Cured Tobacco Leaf Images and Correction

目的研究灯箱中采集烟叶图像时照明电压、不同品牌数码相机、聚焦距离及相机分辨率等成像环境因素对图像识别结果的影响,用相对颜色法对因成像环境因素影响而引起的烟叶图像颜色变异进行实时校正。方法通过试验筛选出颜色表现稳定的聚四氟乙烯材料作为颜色参照白板,在灯箱环境中,设置不同的因素处理,用数码相机同期采集烟叶与颜色参照白板图像,通过分析烟叶图像R、G、B颜色特征变化来确定成像环境因素构成的影响。提取烟叶图像三颜色分量与颜色参照白板对应颜色分量的比率,即相对颜色分量作为校正烟叶图像识别误差的特征参量。结果照明电压、不同品牌数码相机、相机分辨率相同而聚焦距离不同均使烟叶图像颜色产生变异,从而出现识别误差。结论相对颜色法能够实时校正识别误差,降低因成像环境因素影响而产生的颜色变异,为规范烟叶图像的数字采集环境奠定了基础。

[Objective] The study examined the influences of imagery environmental factors such as lighting voltages in a flue-cured tobacco leaf image capture lamp box, digital camera brands, focusing distances and resolutions on the result of image recognition. Relative color methods were employed to timely correct color variations caused by different imagery environmental factors. [Method] Based on the experiment, a white plane made of Teflon, for its color-stable characteristics, was selected to be the color reference plane. The images of both tobacco leaf under different treatments and its color reference plane were acquired in the lamp box. The influences of imagery environmental factors were clarified through the analysis of changing characteristics of R, G, B color vectors of tobacco leaf images. The relative color, defined as ratio of R, G, B color vectors against color reference planes was calculated. It was used as a parameter for the correction of color variations of tobacco images. [ Result] The results showed that lighting voltage in the lamp box, digital camera brand and given the same resolution, different focusing distances could cause color variations of tobacco leaf images, thus introducing the errors in recognition. [Conclusion] Relative color method was proved to be an effective approach to correct errors, lessen the influences of imagery environmental factors that caused the color variation, and lay a solid foundation for the standardization of shooting conditions for digital capture of tobacco images.