Dither to few colours

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All tools › Colours

Dither to few colours

Error diffusion or an ordered matrix: one looks better, the other tiles and compresses.

It runs entirely in this browser tab: the file you open is never uploaded, and the result is re-encoded from pixels, so its metadata does not come with it.

Settings

Method
Only a solid fill and noise remove what was underneath. Choices: Floyd–Steinberg, Atkinson, Jarvis, Sierra, Bayer 2×2, Bayer 4×4, Bayer 8×8, None.
Levels
Two is one bit a channel, which is the newspaper look. A number from 2 to 32.
Grey first
Off keeps all three channels, which gives a colour dither.
Palette
Colours to dither to, separated by commas. Empty means use the levels above.
Save as
Only PNG keeps transparency. JPEG fills it in. Choices: PNG.

How to use it

  1. Paste your text into the box above, or open a file.
  2. Adjust the settings beside it until the result is what you wanted.
  3. Copy the result, or save it as a file. The result updates as you type.

Questions

Is my picture uploaded anywhere?
No. The whole application is carried as WebAssembly and runs on your own device. There is no server to send anything to, and none of these tools makes a network request while it works — not even the one that reads a photograph's location, which is why it gives coordinates rather than drawing a map.
What happens to the EXIF data?
It is gone. Every result here is written from pixels, so the camera, the date, the location and the copyright field are all dropped. That is the point of the location tool and a surprise to anybody who wanted the copyright kept, which is why every result says so.
Is a blur enough to hide something?
Usually not. A blur and a pixelation are averages of what was there, and both have been reversed in published work by blurring candidate images the same way and comparing. Only a solid fill or noise removes the information, and the tools say which method you chose.
Why is the example a test pattern rather than a photograph?
Because this workspace ships no image files anywhere, and a base64 photograph pasted into a source file would be one wearing a disguise. The patterns are drawn from nothing when the button is pressed.

Other tools for colours

Convert to grey
Five weightings, and a pure blue comes out anywhere from 18 to 85 depending which.

Invert the colours
The one operation here that is exactly reversible, and it leaves the alpha alone.

Colouring page
A photograph as black lines on white to colour in, with the threshold in your hands because no single value suits both a face and a hedge.

Add grain
Film grain or sensor noise, and the one effect here that adds colours on purpose.

Glitch effect
Channels split and bands slid: a drawing of a fault, in a file that is not damaged.

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