Hello everyone! I want to make edge detection with sobel operator on RGB image using conv2 function. After extracting each color components and convolving sobel operator and image matrix of color components, I unify all resulting channels at the end. The operations can be applied using the link given below. But I am newbie in image processing and when I search for sobel edge detection subject, I generally see the filtered outputs as in black & white or grayscale image forms But my filter function output has some colors beside the black & white or grayscale such as red, yellow, blue etc. What is the meaning of this colors in sobel edge detected image?