Fur Coloration Quantification via Digital Photography

Digital photography was used to estimate animal fur colouration^{25 (link), 30 (link), 65 (link)}. Field and museum samples were photographed alongside a ColorChecker (X-Rite, Michigan, USA) with Canon EOS400D digital camera, 18–55 mm (set to 55 mm) 1:3.5–56 lens. Photographs were black and white-balance corrected (with GIMP 2.8 program) using the white and black references in the ColorChecker for light condition standardization. High-resolution images (TIFF format) were analysed with Hyper-Utility 2 program (www.fujifilm.com) to quantify fur colouration from a square-shaped area on the back of animal’s head (between the ears, pixel size: 40–150). To test for repeatability of colouration estimates (representativeness of dorsal colour), a total of 40 samples were randomly selected with “Sampling Design Tool” (in ArcGIS 10.1⁶⁶ ) on which selected areas for colour estimation were moved to different locations, and calculations were repeated. Red, green and blue reflectance and total reflectance were measured as Red-Green-Blue (RGB, 8 bit, 0–255) standard values.