Colour Perception Quotes

“Like most mammals, dogs only have 2 colour detecting cells or cones. This is in contrast to humans, who have 3. Dogs, therefore see a restricted colour spectrum. However, they are not colourblind, instead they see the world in yellow, blue and grey. For dogs, green, yellow and orange are perceived as yellowish, while purple and blue are perceived as blue, and blue-green as grey. As a result, dogs have a hard time recognising a red ball in a green field.”
― Martin Balluch, The Dog and his Philosopher: A Call for Autonomy and Animal Rights