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Image Tools

Convert Image to Grayscale

Turn a colour image to greyscale using perceptual luminance weights.

or drag it here

image/* · up to 40 MB

85

Lower means a smaller file. Above 90 rarely looks different and costs a lot of size.

Processed in your browser

Fill in the form and press “Process image” to see the result here.

How to use it

  1. 1Select your image, or drag and drop it onto the upload area.
  2. 2Adjust the options if you need something other than the defaults.
  3. 3Press the button. The image is processed on your device - nothing is uploaded.
  4. 4Download the result, or drop in another file to do it again.

About the Convert Image to Grayscale

The conversion uses Rec. 709 luminance weights - 21% red, 72% green, 7% blue - which match how the eye perceives brightness. Averaging the three channels equally, as naive converters do, makes greens too dark and blues too light.

The result is still a full-colour file containing grey pixels. That is deliberate: it keeps the format compatible everywhere.

Questions people ask

Is your image uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your image never leaves your device. You can confirm it by opening your browser's network panel while the tool runs, or by disconnecting from the internet after the page has loaded.

Is it free, and do I need an account?

Yes, it is free, and there is no account, no sign-up and no watermark on the result. The project is funded by optional donations.