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Sphere dithered with Two-Row SierraThe same sphere before ditheringSourceDithered

06Error diffusion

Two-Row Sierra

Reduced version of Sierra using two diffusion rows. Faster execution with slight quality loss.

Author
Frank Sierra
Year
1986
Complexity
low
Processing cost
2 / 5
Use Two-Row Sierra in the editorAll algorithms

How it works

Each pixel is rounded to black or white and the rounding error is pushed onto the neighbors still to be processed. Organic and detailed.

Error diffusion weights, as a fraction of 16, by position relative to the current pixel
Current pixel4/163/16
1/162/163/162/161/16
  • The error of the current pixel is spread over 7 neighbors that haven’t been processed yet.
  • All of the error is carried forward.
  • Rows are scanned in alternating directions (serpentine), which avoids diagonal streaks.