被毛对热成像检测生猪体表温度精度的影响及噪声滤除方法  

Effect of hair on thermometry of skin by infrared thermography and noise reduction method for live pigs

作　　者：贾桂锋[1,2] 蒙俊宇 武墩 王登辉 高云 冯耀泽[1,2] Jia Guifeng;Meng Junyu;Wu Dun;Wang Denghui;Gao Yun;Feng Yaoze(College of Engineering, Huazhong Agricultural University, Wuhan 430070, China;Key Laboratory of Agricultural Equipment in Mid-lower Yangtze River, Ministry of Agriculture, Wuhan 430070, China)

机构地区：[1]华中农业大学工学院,武汉430070 [2]农业部长江中下游农业装备重点实验室,武汉430070

出　　处：《农业工程学报》2019年第4期162-167,共6页Transactions of the Chinese Society of Agricultural Engineering

基　　金：湖北省自然科学基金(2018CFB099);中央高校基本科研业务专项基金(2662016QD002);国家级大学生创新创业训练计划(201810504076)

摘　　要：生猪皮肤的温度分布是表征其生理状态和疾病的重要指标,通常由红外热成像技术(infrared thermography, IRT)检测,然而由于生猪体表附有被毛在热图像中产生大量的温度噪声,降低了IRT对皮肤温度的检测精度。该文针对此问题探索被毛对皮肤温度分布的影响规律,并设计消除被毛影响的热图像降噪算法,提高对温度分布的检测精度。通过对12头生猪试验,分析目标区域在正常被毛和剔除被毛后温度分布的统计量得出被毛在温度分布中产生大量的"峡谷"状低温噪声,显著降低了目标区域的最低温度及平均温度。根据毛发噪声的影响规律提出网格化最大值-双三次插值算法并确定算法的最佳邻域尺寸为4.25mm。采用均方误差、峰值信噪比等指标定量评价算法的有效性,结果表明经算法处理后,均方误差由0.38下降到0.05(P<0.01),峰值信噪比由45.14 dB上升到53.66 dB(P<0.01),说明该算法能够滤除热图像中毛发引起的噪声,可提高IRT对温度分布的检测精度。The temperature distribution of pig skin is an important indicator to characterize its physiological state and disease. However, due to the surface hair coat, the skin temperature accuracy which detected by infrared thermography (IRT) is affected and its ability to diagnosis of fever and disease is reduced. The purpose of this paper is to explore the influence patterns of the coat on the skin temperature distribution and propose the thermal image processing method to eliminate the influence of the coat on temperature accuracy. The animals for experimental data were 12 sows in empty pregnant period with the average ambient temperature of 27.4 and humidity in the piggery of 80.3% respectively. The body surface ℃ temperature was measured by hand-held infrared thermal imager (Fluke, Ti 300) with a resolution of 240 pixels×180 pixels and sensitivity of 50 mK. And it also carried a laser distance measuring sensor with a resolution of 0.01 m to measure the distance between the measured object and the thermal imager. The statistics of the temperature distribution detected by IRT from the region of interest (ROI) under normal coat (NC) was compared to that under shed coat (SC) state. The statistical data indicated that the hair coat produced a large number of “canyon”-like low temperature noise in temperature distribution in NC state, which reduced the minimum temperature and average temperature of the ROI, but had no significant effect on the maximum temperature with diagnostic ability. According to the noise distribution characteristics and the influence pattern, an image noise filtering algorithm named the grid maximum value bicubic interpolation filter (GMBI) was proposed. The GMBI algorithm consisted of three steps including image mesh segmentation, filtering with maximum value and image bicubic interpolation. The key problem of GMBI was how to select the appropriate neighborhood size to ensure that each block contained at least one skin temperature value and the resolution was as high as possible. In this stu

关 键 词：红外热成像 温度分布 滤波器 猪 图像插值 算法 

分 类 号：S818.2[农业科学—畜牧学]