How to use
- Optionally upload an image to plot its colors on the chart.
- Use the Inspector tab to pick a color and read its L*, a* and b* values, which are also marked on the chart.
- Use the Delta-E tab to choose a reference color and a sample color and read the color difference.
The chart is a plane of the CIE Lab color space with the a* axis running from green to red and the b* axis from blue to yellow. When you upload an image, it is shrunk to a small 64 by 64 sample and its pixels are plotted as colored dots, so you can see how widely its colors spread. Dots are drawn using their a* and b* values.
Three buttons switch the highlighted gamut between sRGB, AdobeRGB and P3, and a checkbox shows or hides the outlines. Each outline is calculated from the color space itself: the surface of its RGB cube is converted to Lab and the outermost point at every hue angle is joined up, so you see the real shape of the gamut projected onto the a*b* plane. Because lightness is flattened in this view, a color can sit inside an outline and still be out of gamut at its particular lightness.
The Inspector converts the HEX color you pick to Lab. It treats the input as an sRGB color, and it shows the HEX, the RGB triple and the L*, a* and b* values. A white ring on the chart marks the color's position.
The Delta-E tab takes two colors and reports the difference between them with the CIEDE2000 formula. CIEDE2000 corrects the plain straight-line distance in Lab for how human vision weighs lightness, chroma and hue, so it matches perceived differences better, especially for small ones. A value below about 1 is usually not noticeable.
All calculations run in your browser, and images are not uploaded.
FAQ
Which Delta E formula is used?
CIEDE2000, which adjusts the Lab distance for lightness, chroma and hue so it follows human perception more closely.
Are the gamut outlines exact?
They are calculated from each color space's RGB cube and show its true outline on the a*b* plane. Lightness is not shown, so use them as a guide rather than for exact gamut mapping.
What color space does the Inspector assume?
The HEX value is read as sRGB and converted to Lab.
How many pixels of my image are plotted?
The image is reduced to a 64 by 64 sample, and only a subset of those pixels is drawn.
Is my image uploaded?
No. It is processed in your browser.