Read up and familiarize with Canvas before attempting to implement. https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Pixel_manipulation_with_canvas#The_ImageData_object
Read up and familiarize with Canvas before attempting to implement.
https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API
https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial
https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Pixel_manipulation_with_canvas#The_ImageData_object