Create new project
Add mouse, text, and canvas objects
Give the canvas object an image and position it at 0,0
Go to the event editor and add a "every tick" condition.
Add the action: text-> set text to canvas.rgbaAt(int(mouse.x), int(mouse.y))
Run it and the text object will tell the color under the mouse on the canvas object.
Int() is used since mouse.x can give values like 10.5 when window scaling is used and the value needs to be a whole number.
.rgbaAt uses x and y values relative to the top left of the canvas object. So if you moved the canvas object from 0,0 you'd have to change the expression to:
Finally notice it only gets the color from the canvas' own texture. Use the drawing actions to change this texture.