Are my images uploaded to a server?

No. Everything runs in your browser, so the image never leaves your device and nothing is stored on a server.

Grayscale

Convert an image to black and white.

Runs in your browser, nothing is uploadedFree, no signupNo watermark

Drop an image here

or click to choose one. It never leaves your device.

Before and after

See what changes

Six Thridy 3D food icons arranged on a warm gradient background — Luminance-weighted, so the greens and reds keep their tonal separation instead of collapsing into the same grey.

Luminance-weighted, so the greens and reds keep their tonal separation instead of collapsing into the same grey.

Drag the handle across the image. The right-hand side is this tool's output, not a mock-up of it.

Before: Colour
After: Black and white

Three steps

How to use the grayscale

01
Add your image
Drop in any colour photo or graphic.
02
Convert to black and white
Apply it fully in one click, or dial back the amount for a partly desaturated look.
03
Download
The result is a proper luminance-weighted monochrome, not a flat channel average.

Why this one

What makes it different

Weighted for how eyes work

Green contributes far more to perceived brightness than blue, so a weighted conversion keeps tonal separation that a naive average flattens.

Partial amounts, not just on or off

A partly desaturated image is a distinct and useful look, and it needs a dial rather than a switch.

Unifies a mixed set

A grid of photos taken in different light stops fighting each other the moment colour is removed.

Where it runs: Your browser, not a server
Uploads: None, ever
Account: Not required
Watermark: Never added

The short version

About grayscale

Removing colour is a design decision rather than a correction, and its most practical use is consistency: a set of photographs shot in different light and different seasons stops looking like a set the moment colour is involved, and starts looking like one the moment it is not. Doing it with proper luminance weighting is what keeps the result from going muddy.

Questions

Grayscale FAQ

How is this different from setting saturation to zero?

A proper grayscale conversion weights the red, green and blue channels by how much each contributes to perceived brightness. Averaging them equally makes reds too light and greens too dark.

Does black and white reduce file size?

Somewhat, since there is less colour information to store, though the saving is smaller than most people expect because brightness detail dominates the file.

Can I get the colour back afterwards?

No. The conversion discards the colour data. Keep the original file if there is any chance you will want it.

When is black and white the right choice?

When colour is inconsistent across a set, when it distracts from form and texture, or when the image needs to sit quietly behind something else, like text.

Free, and staying free

The tools are free because the icons are the business.

Thridy is a library of thousands of 3D icons in one consistent style, free for commercial use with no attribution and no account. The tools exist so you never have to upload an image to somebody else's server to resize it.

Browse the icons Request an icon

Keep going

Blur Image

Apply a smooth Gaussian blur by any amount.

Pixelate Image

Pixelate an image or hide part of it in blocks.

Sharpen Image

Bring out edges and detail with a sharpen pass.

Brightness

Brighten or darken an image.

Contrast

Increase or soften the contrast of an image.

Saturation

Make colours richer or more muted.

All tools