Image Threshold

Convert a photo to pure black and white at the exact level you choose.

Threshold an image

Choose an image

Threshold: 128

Source: No image loaded

Thresholding runs on a local canvas and your photo is never uploaded.

Common questions about the free online image threshold.

Choose your photo, move the threshold slider until the black and white areas look right, then click Download to save the PNG.

No. Each pixel is compared with the threshold on a canvas in your browser, so your image never leaves your own device.

Every pixel brighter than the threshold becomes pure white and every darker pixel becomes pure black, leaving only two tones in the output.

Start at 128 and move the slider until the subject separates cleanly. Lower values keep more white, higher values keep more black.

The tool uses standard luminance weights of 0.2126 red, 0.7152 green and 0.0722 blue, which matches how the human eye sees brightness.

Thresholding produces exactly two tones, pure black and pure white, while posterizing keeps several colour levels and stays in colour.

Cleaning up scanned text, extracting signatures, preparing stencils, making high contrast graphics and tracing shapes for vector work.

Yes. The tool is fully responsive and the threshold slider works with touch on phones and tablets as well as with a mouse.

Yes. It is completely free and unlimited, with no account, no sign-up and no watermark on your downloaded image.

Last updated: October 10, 2026