Grayscale Image

From each pixel’s luminance: the brightness the eye perceives, with green counting most and blue least (the Rec. 709 weights used for sRGB), computed in linear light. That keeps a red rose as bright as it looks in color, where a plain average of red, green and blue would make it too light.

Gray tones is a classic black-and-white photo with 256 shades of gray. Black and white keeps only pure black and pure white, split at the threshold you choose: good for scans of text and line drawings. Dithered also uses only black and white, but spaces the dots so that areas still look gray from a distance, as newspapers and laser engravers do.

A gray JPG or PNG stores one channel instead of three. The picture looks the same as a gray color file but takes less space.

The color information is removed from the new file, so keep your original. Nothing is changed on your device: the tool always makes a new file.

Up to 20 files per batch, up to 50 MB each and 200 MB in total. Files are processed one after another; download each one as soon as it is ready, or all of them as a ZIP.

Very large images are refused to keep your browser from running out of memory: above 100 megapixels on computers and 50 megapixels on phones and tablets. On iPhone and iPad, formats other than HEIC are limited to about 16 megapixels by Safari.

It is free to use and there is nothing to sign up for. There are no watermarks and no daily limits.