How to make an image grayscale
- Select Choose files, or drop your photos on the box.
- The tool converts each photo as soon as it is added.
- Select Download for one photo, or Download all for a ZIP. Files end with -gray.
How the conversion works
Each pixel has red, green and blue values. A simple average looks wrong, because the eye sees green as much brighter than blue. The tool instead takes 21.3 percent of red, 71.5 percent of green and 7.2 percent of blue, and uses the sum for all three channels. The result keeps the light and dark balance of the original, which is why the picture looks natural. The tool uses the fast filter built into your browser and falls back to doing the same math pixel by pixel on browsers that do not have it.
When to use it
Black and white photos look classic and hide colour problems such as odd white balance. Grayscale is also useful for documents that will be printed in black ink, for saving ink and for preparing scans before text recognition. Many pictures also compress to smaller files once colour is removed.
Tips
- Make a flat photo punchier with brightness and contrast.
- Prepare a scan for reading text with image to text.
- Shrink the result with the image compressor.
- Convert a PNG screenshot to a smaller file with PNG to JPG.
Good to know
The tool works on the pixels of the whole picture, so it cannot keep one area in colour. If you want a colour splash effect, you need an editor with layers. JPG, PNG and WebP photos keep their format, and each photo is converted by itself, so a failure on one file does not stop the others. Large photos from a modern phone take a moment on older devices but are never uploaded.
Grayscale loses the colour information for good, so keep your original. The tool saves a new file and never changes the one you chose. Everything runs on your device, and your photos are never uploaded.