Black and white threshold

Turn one or more images into pure black and white (each pixel becomes fully white or fully black) based on an adjustable brightness threshold.

Example:
Drag and drop one or more images here (25 MB max each).

How it works

Need to prepare a document scan for printing, create a stencil, or generate a binary mask for further image processing? Set the threshold and the tool first converts the image to grayscale, then turns each pixel into pure white if it's lighter than the threshold, or pure black otherwise.

How do I choose the right threshold value?

A value around 128 (half of the 0-255 scale) suits most balanced images. For a document scanned with a very light background and dark text, a higher value (180-220) isolates the text better while avoiding "eating" thin strokes.

Does the result keep the original colors?

No, the image is first converted to grayscale before the threshold is applied: the final result contains only black and white, no color information is retained.

100% local processing: the thresholding is performed in your browser via our WebAssembly module — your images are never sent to a server.