An image-processing program for automated counting

Abstract

Counts of dense concentrations of birds from aerial photographs have been employed widely (Kadlec and Drury 1968, Heyland 1972, Leonard and Fish 1974, Kerbes and Moore 1975, Harris and Lloyd 1977). More recently computers have been used to improve efficiency and precision of counts from digitized images of birds (Gilmer et al. 1988, Bajzak and Piatt 1990). To create a more interactive environment than these automated counting programs provided, we adapted Macintosh-based, public-domain software for counting black brant (Branta bernicla nigricans) in large flocks staging on water. This software accesses and enhances digitized images; produces tabular output of data; and allows interactive selection of counting parameters that include spectral-reflectance values, size, shape, and orientation. Efficient application of this program depends on high contrast between objects of interest and background, large concentrations of objects of interest, separation of individuals, and consistent image quality. Manual counts can be taken by marking objects with a paint tool; marks are counted automatically. The program does not have pattern recognition capabilities but had a mean (? SE) counting error of 4.17?1.89 percent in a test count of 1,750 birds with 16 images of brant, emperor geese (Chen canagica), and snow geese (Chen caerulescens) when compared to manual counts from the images.