Easy Filters - Intro to GPU Pixel Shaders

Image Manipulation (Contrast, Brightness, Blur, Pixellation)

Greg Surma
7 min readSep 22, 2019

In today’s article, we are going to explore the basics of low-level GPU computations used for rendering graphics. In order to do so, we are going to dive into the world of GPU Shaders and perform some image manipulations like contrast, brightness, blur, and pixellation. By the end of this article, you will be able to perform basic pixel operations using top graphics libraries like OpenGL and Metal (iOS, macOS).

Easy Filters (source: https://apps.apple.com/us/app/id1476720401)

If you want to perform real-time image filtering like in the above app preview you can download the iOS app

and continue reading to implement such effects by yourself!

Why GPU?

Before we start with implementing GPU shaders, let’s start by asking ourselves - why do we need GPUs in the first place?