Submitted to: Applied Engineering in Agriculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/1/2007
Publication Date: 7/1/2007
Citation: Lawrence, K.C., Park, B., Windham, W.R., Heitschmidt, G.W., Thai, C.N. 2007. Evaluation of LED and tungsten-halogen lighting for fecal contaminant detection. Applied Engineering in Agriculture. 23(6):811-818. Interpretive Summary: Lighting is an important part of any digital imaging system. Yet it is often overlooked as a means to improve image quality. Recent research on fecal contaminant detection has used tungsten halogen incandescent lamps for lighting. However, there have been new advances in broad-spectrum, high-power light emitting diodes (LED) that show promise for use in a fecal detection imaging system. This research compared these new LEDs to traditional tungsten halogen lamps for detecting fecal contaminants with a hyperspectral imaging system. Results indicated that there was no statistical difference in fecal detection accuracies between the two lighting systems. However, LEDs have the advantages of having a very long life and they produce much less heat than incandescent lighting. Therefore they are suitable for use in contaminant detection.
Technical Abstract: Lighting for imaging systems plays an important role in image quality. Recent research in detecting fecal contaminants on poultry carcasses with multispectral and/or hyperspectral imaging has relied on common quartz tungsten halogen lamps for illumination. However, as the technology is implemented in a processing plant environment, there is a need to enclose the system to protect it from the harsh environment. This can result in significant challenges in maintaining quality lighting and images due to excessive heat build-up in the system enclosure, degradation in illumination, and frequent bulb changes because of shorter bulb life. Recent advances in high-power white LEDs have provided a feasible alternative to incandescent lighting. This research compared high-power LED lighting to traditional tungsten halogen lamps for contaminant detection. Sixteen contaminant samples of duodenum, ceca, and colon feces, and ingesta were imaged at four different contaminant spot sizes with two different orientations relative to a hyperspectral imaging camera. Detection accuracies were generally better that 99% for all contaminant types and either lighting system although there was one colon sample that had a rather low accuracy, most likely due to blood in the sample. Results indicate that there was no significant difference in detecting fecal contaminants with the fecal detection algorithm that uses the ratio of images centered at 565 nm and 517 nm with either lighting system. The overall detection accuracies were 99.63% and 99.69% for the LED and tungsten halogen lighting systems, respectively. Thus, the advantages of longer bulb life and less heat with LED lighting make it a feasible alternative to traditional lighting, provide that the LED junction temperatures are held relatively constant.