Drag the divider. Left is the original with smooth tones, right is the same picture squeezed into only a handful of shades. Drop the level count until you first notice damage, then see how a smarter dither pushes that point lower. Everything runs in your browser, nothing is uploaded.
All four use the level count above. Plain rounding makes bands. The other three trade bands for texture, and your eye does the averaging.
Lower the slider until the right side looks clearly worse than the left, then press lock. Do it for each method and compare. Smaller number means the method hides the damage better, for you, on this screen.
| Method | Picture | Your levels | Mean error |
|---|---|---|---|
| Nothing locked yet. | |||
A normal screen shows 256 greys per channel. With 2 levels each pixel must be black or white. Plain rounding decides each pixel on its own, so a smooth ramp turns into hard bands. Ordered dithering adds a fixed repeating threshold pattern before rounding, error diffusion pushes each pixel's rounding error onto neighbours not yet processed (Floyd and Steinberg weights 7, 3, 5, 1 out of 16), and noise adds random jitter. The mean error number is the average absolute difference per pixel, so dithering often scores worse than rounding while looking better: eyes judge local averages, not single pixels.
Tip: view the pure gradient at 4 levels, then switch the method. Bands appear and dissolve.