Atkinson Dithering

Transform any image into faithful-looking 1984 Macintosh graphics. This implements Bill Atkinson's dithering algorithm (developed in 1983, shipped in 1984) that made MacPaint's black and white graphics look exceptional on the original Mac's monochrome display.

Atkinson dithering discards 25% of quantization error, creating high-contrast images with sharp edges—perfect for the aesthetic that defined early desktop publishing.

Drop an image below to see the transformation.

Try It Yourself

Bill Atkinson's Original Algorithm

Developed by Bill Atkinson at Apple (1983-1984) for MacPaint and the original Macintosh. The algorithm was designed for the Mac's 512×342 monochrome display and 8MHz processor.

How It Works:

1. Convert to grayscale: Transform RGB pixels using luminance weighting
2. Quantize: Compare each pixel to threshold 128—below becomes black (0), above becomes white (255)
3. Calculate error: error = original_value - quantized_value
4. Distribute error: Spread 1/8 of error to each of 6 neighboring pixels
5. Discard remainder: 25% of error is intentionally lost

Error Distribution Pattern:

	P	1/8	1/8
1/8	1/8	1/8
	1/8

Processing moves left-to-right, top-to-bottom. Error spreads to 6 future neighbors: right (x+1,y), far-right (x+2,y), down-left (x-1,y+1), down (x,y+1), down-right (x+1,y+1), and two-down (x,y+2) positions. Pattern extends +2 pixels right and +2 pixels down, but never extends left or up from current position.

Why It's Different:

Unlike Floyd-Steinberg (which distributes all error via coefficients 7⁄16+3⁄16+5⁄16+1⁄16=16⁄16=100%^†), Atkinson deliberately discards 25% of error (distributing only 6⁄8≈75%). This prevents "muddy" midtones and creates the crisp, high-contrast aesthetic perfect for Mac's interface elements and line art.

The algorithm prioritized visual clarity over smooth gradations—exactly what was needed for desktop publishing and the Mac's revolutionary graphical interface.

The Legacy of Bill Atkinson

Bill Atkinson (1951 – 2025) was a key member of the original Macintosh team at Apple. Beyond developing this dithering algorithm, he created MacPaint, HyperCard, and contributed to QuickDraw - the Mac's revolutionary graphics system.

The Atkinson dithering algorithm was specifically designed for the Mac's 512×342 pixel, 1-bit display. By discarding 25% of the error, it avoided the "muddy" midtones common in Floyd-Steinberg dithering, creating images with more "snap" and clarity on the high-contrast display.

Made with ❤️ and AI for the classic Macintosh® aesthetic
This implementation is based on Bill Atkinson's original algorithm

Legal: Macintosh® and Mac® are registered trademarks of Apple Inc. ChicagoFLF font by Robin Casady is Public Domain. This page is not affiliated with Apple Inc.