Dithering – Part 2: The Ordered Dithering

Summary

Understanding Threshold Map in Ordered Dithering. tap/click the right side of the screen to go forward →Hi! Welcome back to part 2 of my dithering series!← tap/click the left side to go backIf you missed part 1, please check it out first! I've covered how dithering simulates more colors than actually exist.← or use arrow keys to navigate →This part dives into ordered dithering, a method using a threshold map to decide each pixel's final color*.*Note: This series covers grayscale dithering to two colors only: black & white. Multi-color dithering is possible, but it will not be covered here.There are many ways to build a threshold map, each creating a unique visual pattern.I'll guide you through how it works and how it forms those unique patterns.Please note that this isn’t a technical deep-dive. It’s just a visual exploration of the logic behind ordered dithering.I personally grasp ideas much better when I can see them visually, so I hope this helps you too!Let’s start!First, a quick recap on quantization: the process of reducing colors in an image.Grayscale images use many shades, from black to white.Now, imagine our display can only show pure black and white.We must convert those gray shades into black or white. This is what quantization does.One way is by rounding: dark shades become black, and bright shades become white.Another way is by setting a threshold. Anything below it turns black; anything above it turns white.The threshold controls the quantization output: lower thresholds can turn darker shades white, while higher ones can turn brighter shades black.Now, imagine using multiple thresholds at once, each with a different value.Quantizing a single color now gives us a mix of black and white pixels.The result reflects the original brightness: brighter inputs get more whites, while darker inputs get more blacks.This is essentially how a threshold map works in ordered dithering.It converts gray shades into black & white patterns that mimic the original image's...