Make an image black and white
Turn any image grayscale, privately, in your browser.
What to know
Colour is removed using Rec. 709 luma weighting — roughly 21% red, 72% green, 7% blue. That matches how human vision weights each channel, so the result looks natural rather than flat. Simply averaging the three channels, which many tools do, makes greens too dark and blues too light.
Questions
Is anything uploaded to a server?
No. Every tool on this site runs inside your browser using standard web APIs. There is no upload, no account, no logging and no server holding your data afterwards. You can confirm it by opening your browser's developer tools and watching the network tab stay empty while you work.