When you open any serious image processing tool, from Photoshop to GIMP to Turbo Dither, you are faced with a dropdown menu of algorithms. The two most famous names you'll see are **Floyd-Steinberg** and **Atkinson**.
They are both 'Error Diffusion' algorithms, meaning they work by pushing color residuals to neighboring pixels. Yet, they produce drastically different aesthetics. One strives for accuracy; the other strives for contrast. Let's settle the debate once and for all.
Floyd-Steinberg: The Mathematical Ideal
Invented in 1976 by Robert Floyd and Louis Steinberg, this algorithm is the gold standard for a reason. Its goal is simple: maximize detail preservation.
When a pixel is quantized, Floyd-Steinberg distributes 100% of the error to four neighbors: 7/16ths to the right, 3/16ths down-left, 5/16ths down, and 1/16th down-right. Because it pushes *all* the error forward, the average brightness of the image is perfectly preserved.
- The Look: Smooth, fine-grained, and detailed. It handles subtle gradients beautifully.
- The Downside: It can look 'noisy' or chaotic. In very light or dark areas, it can create 'worm' artifacts—little squiggly lines of pixels.
- Best Use: Photographs, portraits, and images where texture matters more than sharp lines.
Atkinson: The Macintosh Aesthetic
Enter Bill Atkinson. In the early 1980s, he was a key engineer at Apple working on the original Macintosh. The Mac had a razor-sharp black-and-white CRT monitor. When Atkinson tried using Floyd-Steinberg, he found it too messy. The 'noise' made the clean Mac interface look dirty.
His solution was brilliant: **Throw away some of the error.**
The Atkinson algorithm only propagates about 75% of the error. The other 25% is discarded. This means that if an area is light gray, it tends to drift towards white. If it's dark gray, it drifts to black. The middle tones are cleared out.
Head-to-Head Comparison
- Contrast: Atkinson creates much higher contrast images. Shadows become pure black; highlights become pure white.
- Structure: Atkinson preserves geometric shapes better. It looks 'cleaner' and more structural, which is why it was perfect for the Mac OS UI.
- Gradients: Floyd-Steinberg wins here. Atkinson will often 'band' or break apart smooth gradients because it discards the subtle error info needed to represent them.
Which Should You Use?
Use **Floyd-Steinberg** if you are converting a photograph and want it to look as realistic as possible within the limits of your palette.
Use **Atkinson** if you want that iconic 'Retro Computer' look. It is the definitive algorithm for 1-bit art, HyperCard stacks, and 'glitch' aesthetics. It feels intentional and designed, rather than just processed.
Experience the difference yourself.
Try Atkinson Dither