Implementing Block Dithering in GLSL


Block dithering is a technique used in image processing to create a black-and-white image by averaging pixel values within a block. This guide will explain how to implement block dithering in GLSL (OpenGL Shading Language) without diving into the code details.

Overview of the Process

Our shader processes an input texture to produce a dithered black-and-white image. The main steps involved are:

  1. Dividing the Image into Blocks: The image is divided into small blocks of a specified size. Each block will have its pixel values averaged to determine the threshold for dithering.
  2. Calculating the Average Value: For each block, we calculate the average value of its pixels. This average value is used as a threshold to decide whether a pixel should be black or white.
  3. Applying the Threshold: The average value calculated in the previous step is used as a threshold. Pixels within the block are compared against this threshold to determine their final color (black or white).
  4. Outputting the Final Image: The shader combines all the processed blocks to produce the final dithered image, which is then displayed.

To see this shader in action and experiment with it yourself, visit the ShaderToy link. Happy coding!

Drag the mouse right and left on the shader ( or simply click in mobile ).