Digital Camera Based Color Sensor for Determining Leaf Color Level of Paddy Plants

Abstract

Abstract — Determining leaf color level of paddy plants is a practical way to decide fertilizing dosage. Currently the color level is measured by using a leaf color chart. Aiming at applying appropriate fertilizing dosage upon any specific locations in the field, the color levels of paddy plants across the field needs to be measured. A charge couple device (CCD) camera based sensor was developed in this research to determine the leaf color levels of paddy plants by referring to the 4 levels IRRI leaf color chart (LCC). The sensor is driven by a laptop computer mounted on a single wheeled chart, pulled manually across the paddy field. During the traffic, the camera periodically captures each 115 cm x 98 cm field area from 140 cm above the ground, saved into a VGA sized JPG image. Another computer program then recognizes the color levels of all captured images, and then finally plots them in a spatial map. The accuracy of the recognition were 33.4% for color level 2, 100% for color level 3, and 67% for color level 4. Some obstacles were still found, such as the wheel slip during the traffic, the varying light intensity during the day, and the vibration during the traffic which reduce the sharpness of the images.