Printing, Soft Proofing & Color Management in LR 1.2: Two Questions

Question

Printing, Soft Proofing, and Color Management in LR 1.2: Two Questions
There are 2 common ways to set color management in Adobe CS2:
1. use managed by printer setting or,
2. use managed by Adobe CS2 program.
I want to ask how Color Management for Adobe LR 1.2 differs from that in CS2?
As is well known, Color Management by printer requires accurate printer profiles including specific model printer, types of ink and specific paper. It is clear that this seems to work well for LR 1.2 when using the Printer module.
Now lets consider what happens one tries to use Color Management by Adobe LR 1.2. Again, as is well known, Color Management by printer must be turned off so that only one Color Management system is used. It has been my experience that LR 1.2 cant Color Manage my images correctly. Perhaps someone with more experience can state whether this is true or what I might be doing to invalidate LR 1.2 Color Management.
Specifically, I cant use Soft Proofing to see how my images are changed on my monitor when I try to use the edit functions in LR 1.2. Martin Evening states in his text, The Adobe Photoshop Lightroom Book that it is not possible to display the results of the rendered choices (Perceptual or Relative) on the display monitor. While it is not clear in Evenings text if this applies to LR 1.2, my experience would suggest that it still applies to the 1.2 update even though the publication date of his book preceded this update.
Can someone with specific knowledge of Adobe LR 1.2 confirm that Color Management and Soft Proofing with LR 1.2 hasnt been implemented at the present.
The writer is a retired physicist with experience in laser physics and quantum optics.
Thanks,
Hersch Pilloff

Answer 1

Hersch,
since just like me, you're a physicist (I am just a little further from retirement ;) ) I'll explain a little further. computer screens (whether they are CRT or LCD) are based on emission (or transmission) of three colors of light in specific (but different for every screen) shades of red, green, and blue. This light stimulates the receptors in your eye which are sensitive to certain but different bands of red, green and blue as the display emits, making your brain think it sees a certain color instead of a mix of red green and blue. Printers however, produce color by modifying the reflection of the paper by absorbing light. Their color mixing operates completely differently than displays. When you throw all colors of ink on the paper, you get black (the mixing is said to be subtractive) instead of white as you get in displays (the mixing there is additive). The consequence of this is that in the absence of an infinite number of inks you cannot produce all the colors you can display on a monitor using a printer and vice versa. This can be easily seen if you compare a display's profile to a printer profile in a program such as Colorsync utility (on every mac) or
Gamut vision. Typically printers cannot reproduce a very large region in the blue but most displays on the other hand cannot make saturated yellows and cyans.
Here is a flattened XY diagram of a few color spaces and a typical printer profile to illustrate this. Most displays are close to sRGB, but some expensive ones are close to adobeRGB, making the possible difference between print and screen even worse.
So, when the conversion to the printer's profile is made from your source file (which in Lightroom is in a variant of prophotoRGB), for a lot of colors, the color management routine in the computer software has to make an approximation (the choice of perceptual and relative colorimetric determine what sort of approximation is made). Soft proofing allows you to see the result of this approximation and to correct specific problems with it.