Black and white image converter

Convert images to pure black and white: every pixel becomes either black or white, with an automatic or hand-picked threshold, or a dithered pattern that keeps shading. Good for stencils, laser engraving, signatures, scanned documents and line art. Want shades of gray instead? Switch the effect to Grayscale.

Images (you can pick several)

No images yet. You can also drop files on this box.

Effect

Effect
Method
Style
Strength

Auto threshold Threshold

Brightness 0
Contrast 0

Changes apply to every image instantly.

Output

Format
Quality

For black and white, PNG gives the smallest file and the cleanest edges.

Black and white vs grayscale

A grayscale image has 256 shades between black and white; a true black and white (1-bit) image has only two. Pure black and white is what a stencil, a vinyl cutter, a laser engraver or a fax needs, and it makes scanned text crisp. Auto picks the threshold with Otsu's method, which splits the image's brightness histogram into the two most distinct groups. Dithered (Floyd–Steinberg) spreads each pixel's rounding error to its neighbours, so a photo still shows light and shade with only two colors.

How it works

Each image is decoded by your browser and drawn on a canvas, then every pixel is recalculated in JavaScript: brightness and contrast first, then the effect. Width, height and transparency stay the same (JPG has no transparency, so transparent areas become white). Nothing is uploaded, so it works for private photos and even offline once the page has loaded. EXIF metadata (camera, GPS location) is removed.

Other effects: grayscale image converter, invert image colors, sepia filter. To change the shape or size too, use crop image, resize image or rotate image. For a whole PDF, use grayscale PDF.

Screenshots of web pages from code

Converting website screenshots for a print handout or a report? The Shotmint API renders any URL in Chromium and returns a PNG, JPG, WebP or PDF, so you can capture pages in bulk and run the images through this page:

curl "https://shotmint.creasework.com/v1/screenshot?url=https://example.com&width=1280&full_page=true" -H "X-API-Key: YOUR_KEY" -o page.png

Each screenshot or PDF is 1 credit. €5 buys 2,000 with no subscription, and credits never expire.

Get 25 free renders a month Try a website screenshot

FAQ

Are my images uploaded? No. Everything runs in JavaScript on this page.

Does it lose quality? PNG output is lossless. JPG and WebP are re-encoded at the quality you pick. The size in pixels never changes.

Can I undo it? Your original files are untouched; this page only creates new copies. Switch the effect to None to compare, or Reset to start over.

Is there a limit? No file count limit and no watermark. Animated GIF and WebP files are processed as their first frame.