How to use Image Grayscale
- Choose one or more images.
- Set Amount: 100% for full grayscale, or less to keep some colour.
- Pick Save as (Same format as the original is the default) and, for JPEG, WebP or AVIF, the Quality.
- Press Convert and download the files ending in -grayscale.
What it does and when to use it
Grayscale removes hue and saturation and keeps only lightness. People use it to give portraits a classic look, to make a set of photos from different cameras match, to prepare pictures for black-and-white printing, or to see whether a design still reads without colour. A partial Amount, such as 30–60%, gives the muted, “faded film” style often used behind text.
If you want a warm brown tone instead of neutral grey, use Image Sepia. Grey photos often look flat at first; a small boost with Image Contrast usually brings them back to life.
How it works
The picture is decoded in a Web Worker in your browser. For every pixel the tool computes a weighted brightness from the Rec. 709 standard, the same weights the CSS grayscale() filter uses:
grey = 0.2126 × R + 0.7152 × G + 0.0722 × B
With Amount below 100%, the colour matrix is blended between the original and the grey result, exactly as CSS does with a partial value. The picture is then saved with the browser’s encoder; nothing leaves your device.
Worked examples
These values come from the tool’s own colour matrix.
| Original pixel | Amount 100% | Amount 50% |
|---|---|---|
| Pure red (255, 0, 0) | (54, 54, 54) | (155, 27, 27) |
| Pure green (0, 255, 0) | (182, 182, 182) | — |
| Pure blue (0, 0, 255) | (18, 18, 18) | — |
| Brand blue #2563eb (37, 99, 235) | (96, 96, 96) | (66, 97, 165) |
What this means in a photo. A red jumper against green grass can turn into two almost equal greys, so the subject disappears. Before converting, check the important colours; if they clash, raise the contrast afterwards.
A whole set of product shots. Select every image at once with Amount 100% and Save as JPEG. Each file is converted the same way and keeps its own name plus -grayscale.
Limits and tips
- Metadata such as camera details and GPS position is not copied into the new file.
- Animated GIFs come out as one still frame.
- Converting twice changes nothing more; grey stays grey.
- To make a black-on-white scan crisp for printing, try Image Threshold instead.
- To shrink the result for an upload form, follow with Compress Image to 50 KB.
Frequently asked questions
Why does red turn so dark and green so light?
What does Amount do?
Is the saved file a true single-channel grayscale image?
Can I turn it into pure black and white with no greys?
Does it keep transparency?
How do we know nothing is uploaded? Test it yourself on the privacy proof page.