How to reduce image resolution?

Question

JavaScript

I want to write a small photo editor in JavaScript. How to reduce image resolution? Let's say the resolution is 1280*800, but I want to reduce it to 640*400 and save it to the user's computer. By what algorithm can this be done? I know that there is something similar in PHP, but I need it in Js, i.e. do all the work on the client side. Maybe there are ready-made solutions? If not, how to write such an algorithm? Somehow they make them. I'm probably already tired with such questions, but still, maybe someone knows :)

Answer 1

read about canvas