The HDR Color picker looks similar to the ordinary color picker, but it has a few additional properties.
You can set the Current Brightness of a color to greater than 1. This creates an area of whiteness at the top left of the color selector.
Click on Tonemapped preview to see a preview of the color produced by the color picker. Set the Tonemapping Exposure value to the value you have set in the Tonemapping script attached to your camera (in this example 2.2).
The HDR color is also shown in the box at the top of the HDR Color picker with the falloff colors shown to the edge of the box.
HDR colors can be saved as presets just like ordinary colors. They are marked in the presets list with “h” to indicate they are HDR.