L*a*b* input
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In this example, we start with L*a*b* D50 values. We want to obtain the equivalent Adobe (1998) RGB values, get the equivalent Munsell Hue, Value and Chroma (HVC), and convert the input to sRGB. Because our L*a*b* values are relative to D50 and because the Adobe (1998) input space is based on D65, we need to check the "L*a*b* / L*u*v* in D50" radio button under the L*a*b* display; please note that we would not check this button to input D65 L*a*b* values. The Adobe (1998) space was selected because the input color is within the space gamut; this can be easily checked since an out-of-gamut input would automatically be flagged by exclamation points over the RGB data displays while entering the L*a*b* values, and because the Adobe RGB values are not clipped at zero or 255. We obtain Munsell 4.1G 5.7/14.5, a value with fractional accuracy which is more precise than what we would get in a Munsell Book of Colors (or in BabelColor CT&A even larger Munsell Color Deck). As we see in the chromaticity diagram the color, represented by the green square, is outside of the sRGB gamut. Clipping has occurred for the sRGB red coordinate; on the RIGHT side, a red exclamation point ( ! ) appears over the corresponding display box of Space #2. The clipping error is 7,54 CIE94; the error can also be evaluated using the other formulas shown in the opened list box. There is another (green) exclamation point ( ! ) in the larger color patch, indicating that the Space #1 color cannot be exactly represented by the currently selected display profile, which is sRGB in this screenshot (here we have a target space, Space #2, which is the same as the display profile; it is thus expected that the same clipping will occur). This explains why the Space #1 and Space #2 colors appear the same; if we had a larger display gamut, corresponding to Adobe RGB for example, then we would see two different greens, such as in the following image, where there is no clipping in the larger square representing Space #1:
Note: This is a simulation since the true colors can only be seen on a large gamut display. In particular, the smaller square would be the same color as in the top screenshot, and the larger square would be more saturated than in the top screenshot. Another way to confirm this is to look at the Delta parameters, most of the difference is in Chroma, with a difference of -20,3 in DeltaC* when converting to sRGB. |
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