QTR-Quadtone RIP

First I apologize for having posted the same on the BWprinting group 
too : Steve has been quite helpful on this group, and I have not seen 
him intervening on QTR group. So please do not be mad at me for those 
double posting...

Quote :

I have been trying hard to understand the QTR ICC tool. I thought I
got it but... no!!!

When the stepwedge is printed linearised and profile converted I got
values far lighter than when non profil-converted :
(L* only)
DEN Linear Linear+converted
0 96,45 96,14
5 92,9 93,59
10 89,24 90,35
15 85,27 86,92
20 81,34 83,99
25 77,4 80,57
30 73,61 77,03
35 70,04 73,91
40 66,63 70,39
45 62,3 66,99
50 58,03 63,17
55 53,54 58,76
60 50,04 55,38
65 45,97 51,15
70 41,94 46,6
75 37,92 42,89
80 34,08 38,01
85 30,44 31,62
90 25,85 26,12
95 21,73 21,11
100 17,7 17,89

Basically it looks like it applies a higher gamma...

I just took the QTR stepwedge, opened it with no color managed
conversion (CS then assumes it will have the default grey profile
e.g. 15% dot in my color settings), converted to QTR ICC and print it
in QTR.

Anyway, when visualizing the kTRC tag of the QTR profile, the curve
does look like it maps destination values lighter than the source
ones in a nice below the 45° line curve.

Last to make it easier : kTRC seems (from ICC spec.) to be build from
XYZ. I don't have PM, so I just past Lab values in a PM measurement
file I got. PM XYZ look pretty strange with double digit figures
while XYZ range from 0 to 1.99... ?

So 2 questions :

1. Do I need to also input XYZ in PM file to feed QTR create ICC and
if so how do I convert "real" XYZ to the PM XYZ format ?
2. Is that normal QTR ICC lightens a file ?

Any help would be more than welcome...

Unquote

Just to add also to it, Steve mentionned BPC is included in the 
profile, not allowing perfect soft-proofing : I have not experienced 
this was limiting the soft proofing... And may have missed something.

Olivier