Algorithm guide

Atkinson Dithering Online

Updated June 2026 · 5 min read

Atkinson dithering online recreates the iconic look of early Macintosh graphics — high-contrast, airy, and unmistakably retro. Diffused Editor runs Bill Atkinson's algorithm in your browser with the Classic Mac preset, live preview, and no upload required.

What is Atkinson dithering?

Atkinson dithering is an error diffusion algorithm developed by Bill Atkinson in the early 1980s for the original Macintosh computer. Like Floyd-Steinberg, it quantizes each pixel to the nearest palette color and distributes the rounding error to neighboring unprocessed pixels. But Atkinson's version differs in two important ways: it spreads error across a wider six-pixel neighborhood, and it deliberately retains only 75% of the error — the remaining 25% is discarded.

That partial error retention produces a lighter, more open dither pattern. Highlights stay bright, shadows stay clean, and the overall image feels less dense than Floyd-Steinberg output. This is exactly the aesthetic that defined Macintosh graphics from 1984 through the early 1990s — the look of HyperCard illustrations, MacPaint drawings, and classic desktop publishing.

Atkinson vs Floyd-Steinberg

Both algorithms are error diffusion methods, but they produce noticeably different results:

• Floyd-Steinberg — distributes 100% of error to four neighbors; smooth, balanced, general-purpose
• Atkinson — distributes 75% of error to six neighbors; lighter, airier, more contrasty

Floyd-Steinberg preserves more tonal information in mid-tones, making it better for photographs with subtle gradients. Atkinson sacrifices some mid-tone detail for a crisper, more graphic appearance — ideal when you want the image to read as illustration rather than photograph. When you apply Atkinson dithering online, you are choosing style over smoothness.

The retro Mac aesthetic

The original Macintosh displayed 1-bit black-and-white graphics at 512 × 342 pixels. With only two colors per pixel, dithering was essential for showing photographs, gradients, and shaded UI elements. Atkinson's algorithm became the default because it produced clean, readable results on the Mac's small monochrome screen.

Today, the retro Mac look is a deliberate creative choice. Designers use Atkinson dithering online for album covers, zine layouts, social media graphics, game UI mockups, and editorial illustrations. The aesthetic signals nostalgia, craft, and a handmade quality that flat digital gradients cannot replicate.

When to use Atkinson dithering

Reach for Atkinson when you want a specific retro or graphic look:

• 1-bit black and white — high-contrast portraits, logos, and typography treatments
• Retro Mac graphics — authentic Classic Mac OS visual style
• Illustration and editorial — graphic, poster-like images rather than smooth photos
• Pixel and indie game art — UI elements and character portraits with vintage computing feel
• Zine and print design — raw, high-contrast looks for Riso and screen printing

Avoid Atkinson for photographs where smooth tonal gradation matters — Floyd-Steinberg or Sierra will serve you better in those cases.

How to apply Atkinson dithering online

Diffused Editor makes Atkinson dithering online straightforward with two paths: the Classic Mac Quick Preset or manual algorithm selection.

Quick method: Classic Mac preset

1. Open diffusededitor.com and upload your image.
2. Click the Classic Mac Quick Preset in the Style tab.
3. Preview the result and download a free 50% JPEG.

Manual method: fine-tuned Atkinson

1. Upload your image and select Atkinson from the algorithm dropdown.
2. Enable Grayscale in the Color tab for authentic 1-bit black and white.
3. Set intensity to 100–120% and increase contrast by +15 to +30 in the Adjust tab.
4. Try threshold at 140 for brighter highlights. Keep pattern size at 1 for crisp detail.
5. Use the A/B divider to compare against the original, then download.

Tips for authentic retro Mac results

A few settings push the output closer to genuine Classic Mac graphics:

• Mac Plus palette — select the built-in Mac Plus palette for period-accurate black and white
• 2-color palette — set color count to 2 for strict 1-bit output
• Higher contrast — early Mac screens had limited dynamic range; boosting contrast mimics that
• Simpler subjects — portraits, objects, and bold compositions dither better than busy landscapes
• Lower resolution sources — images around 512–1024 px wide feel most authentic when dithered

Why use Diffused Editor for Atkinson dithering?

You could approximate Atkinson dithering in Photoshop through indexed color mode, but you would lack live preview, Quick Presets, and one-click palette selection. Cloud converters may offer a "retro" filter but rarely implement true Atkinson error diffusion. Diffused Editor provides the real algorithm with full parameter control, client-side privacy, and the Classic Mac preset for instant results.

Learn more about dithering fundamentals in our image dithering guide, or follow the full editor walkthrough in how to dither an image online.

Frequently asked questions

What is Atkinson dithering?

An error diffusion algorithm by Bill Atkinson that spreads 75% of quantization error across six neighbors, creating a lighter dither pattern associated with classic Macintosh graphics.

Can I apply Atkinson dithering online for free?

Yes. Atkinson is included in Diffused Editor's free tier alongside the Classic Mac Quick Preset. No account or server upload required.

Why does Atkinson dithering look like old Mac graphics?

Bill Atkinson created this algorithm for the original Macintosh's 1-bit display. Its lighter error diffusion produced the distinctive high-contrast, open look of classic Mac UI art and early desktop publishing.