Convert an Image to Pure Black & White
Every pixel becomes pure black or pure white — you control the cutoff with a live slider.
100% in your browser — files never uploaded
How the threshold slider works
The tool measures each pixel's brightness, then compares it against your threshold: brighter pixels become pure white, darker ones pure black. Slide left for a darker, heavier result; slide right to lighten. The preview updates live so you can dial in exactly the cutoff your image needs.
Best for scans, signatures and line art
Hard black & white shines where grayscale looks muddy: scanned documents, whiteboard photos, pencil sketches, signatures and stamps. Thresholding removes paper shadows and yellowing in one step, leaving crisp black marks on a clean white field.
Private, in-browser processing
Everything runs on the Canvas API locally — the image never leaves your device, so it's safe for contracts, ID documents and other sensitive scans.
Turn a Phone Photo of a Document Into a Clean B&W Scan
A photographed document carries gray shadows, paper tint and uneven lighting that make it look unmistakably like a photo. Thresholding fixes that: every pixel brighter than your cutoff becomes pure white and everything darker becomes pure black, which flattens lighting artifacts into a clean scan-like page in one step. The live slider matters because no single threshold suits every photo — a bright, evenly lit page cleans up at the default, while a dim photo needs the cutoff moved down to keep text solid.
Signatures, Stamps and Forms That Demand Pure Black & White
Many portals and print workflows require true 1-bit-style black and white — signature uploads that must sit on a transparent-or-white field, fax-bound documents, silk-screen and stamp artwork, laser engraving sources. Continuous-tone grayscale fails those requirements because anti-aliased gray edges render as dither or noise. Threshold conversion produces the hard edges those pipelines expect, and the PNG output keeps them lossless.
When to Use Grayscale Instead
Thresholding is deliberately destructive — it discards every mid-tone, which is exactly wrong for photographs. If you want a monochrome portrait or product shot that keeps shading and depth, use the Grayscale tool instead; it preserves the full tonal range with perceptually accurate luminance weighting. A good rule: documents and line art here, photos to grayscale.
Frequently asked questions
What threshold value should I use?
Start at the default (128) and adjust while watching the preview. Scans with shadows usually want a higher threshold to push the background to white; faint pencil work wants a lower one to keep the strokes black.
Is this the same as grayscale?
No — grayscale keeps every shade of gray, while this tool forces each pixel to pure black or pure white. Use grayscale for photos, black & white for documents and line art.
Will my document photo's shadows disappear?
Usually yes — uneven lighting and paper tint fall below the threshold and turn white. If a shadow persists, nudge the threshold higher until the background clears.
Is the image uploaded anywhere?
No. The conversion runs entirely in your browser and the output downloads directly from memory — nothing touches a server.
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Turn a photo or screenshot into editable text — processed entirely on your device.
OpenData verified: 2026-07-11 · All processing happens in your browser — no files are ever uploaded.