A grayscale image is a type of image that only contains shades of gray, ranging from black (zero intensity) to white (maximum intensity), with no color information. It is a commonly used image representation in computer vision, image processing, and other related fields. Converting a color image to grayscale is a process of removing the color information and keeping only the brightness information of the image.
In OpenCV, the cvtColor function is used to convert an image from one color space to another. To convert an image to grayscale, we need to use the COLOR_BGR2GRAY flag as the second argument of cvtColor function. This flag specifies that we want to convert the image from the BGR color space (used by default in OpenCV) to grayscale.
The cvtColor function takes the input image and creates a new image with the same size and depth, but with only one channel (grayscale). The algorithm for converting color to grayscale varies depending on the application, but a common approach is to calculate the luminance (brightness) of each pixel using the following formula:
Where
