Based on what Gordon and others helpfully suggested I go read about this issue, I think the basic problem comes down to the resolution of the Bayer sensor when it comes to single-color objects. Here's a screen shot of some white & red rose petals from my earlier example with a simulation of a Bayer sensor matrix overlaid:
http://john-reed.smugmug.com/photos/22508724-L.jpg
The Bayer sensor grabs light information (both chroma and luminence) from each one of the sensors in the matrix. Camera engineers design the accompanying sensor filters so that the "red" sensors are predominantly sensitive to red light, the "blue" sensors similarly sensitive to blue light, and the green sensors to green light. For a normal subject not painted in one of the primary sensor colors, all three sensor colors get into the act. For example, the white rose in my example gains the benefit of all three color sensors in recording its image. On the other hand, the red rose "lights up" only the red sensors, or only 1/4 of the sensor array. So when it comes to interpolating the sensor info to create RGB pixels for each of the sensor sites, the red rose details benefit from only 1/4 of the sensor pixels, whereas the white rose draws from all of them. So the white rose is capable of substantially greater detail. The closer one gets to the red subject, the less noticeable is this phenomenon, but when I looked at old rose photos, and red flowers submitted by others, it's really difficult to see a lot of fine detail with any red flowers. I guess the same should be true of blue flowers, if my theory is correct?
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Just let a smile be your umbrella!

John Reed

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