A colorspace is a mathematical model used to represent colors. Usually, colorspaces
are used to represent the colors in a numerical form and to perform mathematical
and logical operations with them. In this book, the colorspaces we mostly use are
BGR (OpenCV's default colorspace), RGB, HSV, and grayscale. BGR stands for
blue, green, and red. HSV represents colors in Hue, Saturation, and Value format.
OpenCV has a function cv2.cvtColor(img,conv_flag) that allows us to change
the colorspace of an image (img), while the source and target colorspaces are
indicated on the conv_flag parameter.