Skip Navigation Links

1931 CIE Chromaticity Diagram

This interactive CIE 1931 Diagram is a Java applet so Java plug-in is required. Cookies are also required to remember the size of the diagram so you will not need to resize it the next time you visit this diagram.

The three buttons on the top of the diagram allow you resize the diagram.

If "Show monochromaitc light" is checked, moving the scroll bar below it will show a dot corresponding to the monochromatic (i.e. single wavelength) light. Its wavelength is displayed below the scroll bar. Its corresponding X, Y, Z and R, G, B values are displayed at left uppper corner.

If "Show monochromaitc light" is not checked, the left upper panel will show the X, Y, Z and R, G, B values corresponding the the point where mouse cursor is.

CIE chromaticity diagram is a 2-D diagram in a 3-D (xyz) space, so the best way to present it is to draw it in the 3-D xyz space and allow it to be looked at from different angle. Biyee has a limted version of 3D CIE 1931 Diagram (Java 3D needs to be installed).   

Since it is impossible for a color monitor with RGB phosphors to display the full spectrum of colors of a true CIE diagram, the part that has negative R, G, or B values are displayed by adding white to them untill the most negative value is raised to zero.

The following table lists different variants CIE 1931 chromaticity diagram

Just diagram Three simple 2-D CIE 1931 diagrams
Diagram w/o added white Three diagrams with negative R, G, B values replaced with zero
Honest Diagrams Three diagrams that do not show the part that cannot be reproduced with RGB
Rotatable 3D Diagram 1931 CIE chromaticity diagram in x-y-z 3D space

These diagrams are applets, so it may take a few seconds to draw on a slow computer, but it is accurate to the limits of the displaying monitor while keeping a small download file.  The problem with using image files for CIE diagrams is that they are either very large bitmap files or compressed lossy files such as JPEG that lose some color accuracy.  These applets will be available as a downloadable JavaBeans for plugging into your application soon.

These diagrams are based on 1931 2-degree CIE xyz color matching functions that remain international standards in both colorimetry and photometry.  International Telecommunication Union uses 1931 CIE color matching functions in their recommendations for worldwide unified colorimetry (ITU-R  BT.709-4, ITU-R  BT.1361).  Most color monitors comply with the standard.  This makes it possible to display 1931 CIE diagrams correctly on different color monitors.  

There are other color coordinate systems most of which are not any kind of  transform of 1931 CIE system, so it is impossible to display diagrams of those system correctly on different monitors that are calibrated with 1931 CIE system.