What is the difference between greyscale and black & white?

Greyscale keeps many shades of grey based on each pixel's brightness. Pure black & white forces every pixel to either fully black or fully white using a threshold, giving a high-contrast 1-bit look.

How is greyscale brightness calculated?

It uses the perceptual luminance formula 0.299R + 0.587G + 0.114B (ITU-R BT.601), which matches how the human eye weights red, green, and blue.

What does the threshold slider control?

In black & white mode the threshold (default 128, range 0-255) is the brightness cutoff. Pixels brighter than the threshold become white and the rest become black, so a lower threshold keeps more white and a higher one makes the image darker.

When should I use black & white instead of greyscale?

Use 1-bit black & white for high-contrast art, scanning line drawings, logos, or preparing images for risograph or laser engraving where only pure black and white print. Use greyscale when you want to keep tonal detail.

Does it keep transparency?

Yes. Only the red, green and blue channels are recomputed; the alpha channel is preserved, so transparent PNGs stay transparent.

Is my image uploaded anywhere?

No. The conversion happens entirely in your browser using the canvas API, so your photo never leaves your device.

Image to Grayscale / Black & White

Grayscale and black & white image converter

Convert any photo to perceptual greyscale or a pure 1-bit black and white image. Greyscale keeps the full range of grey tones, while black & white mode forces every pixel to either black or white for a crisp, high-contrast result — ideal for line art, scans, logos and stencil-style output.

How it works

The image is read into a <canvas> and every pixel is converted to a brightness value using the perceptual luminance formula:

lum = 0.299R + 0.587G + 0.114B (ITU-R BT.601)

Greyscale: each pixel’s red, green and blue are all set to lum, keeping the full 0-255 range of shades.
Black & white: the luminance is compared against a threshold (default 128). If lum ≥ threshold the pixel becomes white (255), otherwise black (0).

Example

A pixel with R=200, G=180, B=120 gives lum = 0.299×200 + 0.587×180 + 0.114×120 ≈ 179.

Mode	Threshold	Output pixel
Greyscale	—	grey 179
Black & white	128	white (179 ≥ 128)
Black & white	200	black (179 < 200)

Everything runs in your browser — your image is never uploaded.