About the RGB to Colortone Converter
An eyedropper hands back three numbers between 0 and 255 and leaves you to work out what they mean. Sampling a photograph, a screenshot or a competitor site produces dozens of those triples, and sorting them into something you can talk about is easier once each one has a name. Paste the triples here and every line comes back paired with the nearest tone from a 131 entry library, with both swatches shown side by side so you can judge the match yourself.
It would be tempting to find the nearest name by squaring the differences between the red, green and blue channels, but that answer is often wrong. RGB is not perceptually even: the green channel dominates apparent brightness, and equal numeric steps look much larger in dark colours than in light ones. Converting both colours to CIE Lab first and measuring there gives a distance that lines up with what you see, which is why the delta E printed beside each name is worth trusting.
Values may be written as rgb(226, 114, 91), as a bare comma or space separated triple, or with percentage channels, and an rgba() alpha is accepted then discarded. Named tones have no opacity of their own. To turn a name back into channel values use Colortone to RGB, and RGB to Pantone covers the same job when the destination is a print spec.
How to use
- Paste RGB triples, one on each line, with or without the rgb() wrapper.
- Press Match to line each colour up against its closest named tone.
- Compare the two swatches to confirm the name suits the colour.
- Copy the results for your palette documentation.
Common questions
- Can I paste values straight from an eyedropper?
- Yes, a bare triple such as 112, 41, 99 is understood, and so are space separated channels.
- Why is the match calculated in Lab rather than RGB?
- Lab distance tracks how different two colours look, while RGB distance exaggerates gaps in dark colours and understates them in bright ones.
- What happens to an alpha value in rgba()?
- The alpha is parsed and then ignored, since a tone name describes hue and depth rather than opacity.
- How many tones are in the library?
- There are 131 entries covering reds, earths, yellows, greens, blues, purples and a full run of neutrals.