I'll try the link again:
http://www.harding.edu/gclayton/color/t ... hroma.html
Here is the Wikipedia article on the same topic:
http://en.wikipedia.org/wiki/Munsell_color_system
The problem of scanning the color of an object is surprisingly complex. The problem of reproducing that color on a computer screen or LED is even more complex.
The sensor itself simply reports the R, G, B and C values of the light that hits it. I have very little doubt that your sensor is accurately reporting what it sees. What it 'sees' is every ray of light hitting it. The field of view covers the entire hemisphere in front of the sensor and the angular sensitivity is shown in figure 3 of the data sheet:
http://www.adafruit.com/datasheets/TCS34725.pdf
So the first problem is that you need to ensure that the sensor only sees colors reflected from your object. This can be done with some combination of optics, masks and/or shrouds. Just putting the object in front of the sensor does not keep it from seeing other things on the periphery.
The second problem is making sure that the light reflected from the object is not a specular reflection, since specular reflections have the color of the light source, not the color of the object.
http://en.wikipedia.org/wiki/Diffuse_reflection If you look at the orange below, you will see an area on the lower left that has white specular reflections from the lights. This will appear to the sensor as a much lighter and paler orange than the light coming from the area just to the right of that.
http://www.rgbworld.com/color.html
Assuming that you have solved the problems of lighting your object and assuring that all the light reaching the sensor is from your object only, It is not sufficient to simply feed the RGB values to a LED and assume they will look the same. The variables here are even trickier:
First, it is unlikely that the R, G and B spectrums of the LED precisely match the R, G and B spectrums of the sensor filters. So exact matches of some colors may be physically impossible.
Next, the R, G and B LED components all have different forward voltages and will respond differently to the varying PWM signal. And, none of the response curves will be linear. The usual technique for correcting this is to implement "gamma correction" tables for each color.
And finally, the human eye does not perceive additive colors synthesized from an RGB LED the same way it perceives reflected colors due to absorption of light on the surface of an object. Plus the fact that our perception of colors is affected by the colors and brightness of its surroundings. The classic book on the subject is "Interaction of Color" by Josef Albers.
