Colorspaces and conversions

A colorspace is a mathematical model used to represent colors. Usually, colorspaces are used to represent colors in a numerical form and 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 stand for Blue, Green, and Red. HSV represents colors in the Hue, Saturation, and Value format. OpenCV has a cv2.cvtColor(img,conv_flag) function that allows us to change the colorspace of an img image, while the source and target colorspaces are indicated in the conv_flag parameter. We have learned that OpenCV loads images in the BGR format, and matplotlib uses the RGB format for images. So, before displaying images with matplotlib, we need to convert images from BGR to the RGB colorspace. Take a look at the following code. The programs read image in the color mode using cv2.imread(), which imports the image in the BGR colorspace. Then, it converts it into RGB...