Image Analysis of Water–sensitive Cards for Spray Coverage Experiments

Watersensitive papers can be useful spray droplet sampling devices provided that their limitations are taken intoaccount. One of these limitations is that the color of the unstained areas on a watersensitive paper changes as the distancebetween stains decreases. An image analysis system and an appropriate image thresholding calibration procedure weredeveloped. Ideally, the calibration is performed for each consistent set of samples. One useful feature of the calibrationprocedure is the estimation of the absolute error in the measurement of the percent area covered. In the example used todescribe the method, the absolute error in percent area covered was estimated to
3.5%.