Grayscale or black and white?
| Feature | Grayscale | Black and white |
|---|---|---|
| Tones | 256 shades of gray | Pure black and pure white only |
| Looks like | A classic black and white photo | A stamp, stencil or photocopy |
| Best for | Portraits, landscapes, printing photos without color | Scanned text, signatures, line art, designs for cutting machines |
| Setting | None needed | Threshold slider, default 128 |
When people ask for a black and white photo, they usually mean grayscale: it keeps every shade between black and white, so skin, skies and shadows still look natural. The Black and white mode gives a graphic, high-contrast look instead, and it’s the one to use when you need clean, solid shapes, for example to tidy up a scanned page or turn a logo into a single-color stencil.
How the conversion works
Grayscale mode works out each pixel’s brightness with the Rec. 601 weighting: 0.299 R + 0.587 G + 0.114 B. A plain average would treat the three colors equally, but our eyes see green as much brighter than blue. With this formula, pure green becomes a mid gray (150 out of 255), pure red a darker gray (76) and pure blue almost black (29).
Black and white mode calculates the same brightness, then compares it with the threshold. Pixels darker than the threshold become black and the rest become white. The default, 128, sits halfway between 0 and 255.
Tips for better results
- Colors that look very different can turn into the same gray. Pure red (255, 0, 0) and a medium green (0, 130, 0) both come out at about 76, so a red flower can blend into its leaves. Photos with strong light and shadow usually convert best.
- For scans and signatures, use even lighting. A shadow across the page can turn into a black patch at a high threshold.
- Need a soft, colorless background? Convert here, then use the blur tool. For a black and white profile picture, convert the photo first, then make it round with circle crop.