How to make a picture black and white
- Choose a style: Greyscale for photos, or Pure black and white for documents and drawings.
- Add your images by choosing them or dropping them on the box above.
- Download the result. Tap a thumbnail to compare it with the original.
Which style should you choose?
| Style | Looks like | Best for |
|---|---|---|
| Greyscale | A classic black-and-white photo with soft tones | Portraits, landscapes, old-style effects, printing photos on a mono printer |
| Pure black and white | Ink on paper: only black or white, no grey | Signatures, scanned forms, receipts, sketches, stencils, line art, photocopy-style documents |
Pure black and white is also the clean way to prepare a signature for pasting into a document. Scan or photograph it on white paper, convert it, then crop it tightly.
How the conversion works
A colour pixel has red, green and blue values. Our eyes are much more sensitive to green than to blue, so a simple average would make greens look too dark and blues too bright. This tool uses the standard brightness weights from the Rec. 709 colour specification (about 21% red, 72% green and 7% blue) to get grey tones that match how bright the colours looked.
For pure black and white, each grey is then compared with a threshold chosen for that image, and becomes either black or white.
Tips for better black-and-white photos
- Look for contrast. Strong light and shadow, textures and shapes work best once colour is gone.
- Mind similar colours. A red flower on green leaves can turn into one flat grey; such scenes may suit colour better.
- Clean up scans first. For documents, crop away the scanner bed and rotate pages straight before converting, so the threshold is based on the page itself.
Formats
JPG, PNG and WebP images keep their format. AVIF, BMP and GIF images are saved as PNG. Transparent areas stay transparent. For documents, PNG gives the sharpest edges and the smallest files.
Privacy
Scans of IDs, letters and signatures are personal. The conversion runs inside your browser, so the images never leave your device.
Questions
What's the difference between greyscale and black and white?
Greyscale keeps every shade of grey between black and white, which is what people usually mean by a black-and-white photo. Pure black and white uses only two colours, black and white, which suits text, signatures, line drawings and scanned documents.
Why do some colours look the same in grey?
Greyscale shows brightness, not colour. A red and a green of similar brightness become a similar grey. That's normal, and it's why black-and-white photographers think in light and shadow.
How is the black-and-white threshold chosen?
Automatically, with a method called Otsu's threshold. It analyses all the grey levels in the image and picks the point that best separates dark areas from light ones, so each image gets a threshold that suits it.
Will a pure black-and-white image be smaller?
Usually much smaller as PNG, because two colours compress very well. As JPG the saving is smaller, since JPG is designed for photos with many shades.
Last reviewed 5 November 2026