Digital BW, The Print

> From: odesmais <odesmais@...>

> 
> My problem is :

> 1. I expected the compression resulting of the conversion should be
> in the form of a "perfect" curve but if you draw the G2.2profiled L*
> curve (excel)you will see "bumpings" (I guess this is the way you say
> it in English). G2,2 is a straight line, while G2,2_Profil is neither
> a straight line (fine) nor a perfect curve in a kind of gamma shape
> one.

I will let Roy answer this as he is conversant with the white point and
black point scaling.

> 2. Why the Generic Matte Profile and the QTR ICC created one don't
> have the kTRC curve in the same part of the 45° line (GMprofile
> above, mine below?).In IMHO both should be in the upper part
> (lighter) because if Lblack is no pure black the all values should be
> lighten "perceptual". Besides GMprofile kTRC is a perfect curve again
> in a fine gamma shape look, while the one I get is an bumped bowl
> shape (what my 3-years-old daughter would draw as a smile !!!). It
> doesn't matter really nut this is where I feel it demonstrate a
> problem.

The generic ICC profiles have XYZ as the PCS and hence are concave curves -
you are looking at XYZ_Y and hence it has curvature.  QTR Create ICC uses
Lab as the PCS.  If there were no BPC being done and your linearized
greyscale was perfectly linear then the kTRC would be a straight line
(whereas if the PCS were XYZ it would still be curved like the generics).
Roy will have to comment on the effect of the BPC he is doing.

> 3. I get significant blockages in the 90-100 once the profile is
> applied so that I did not even bother running the Piezo test for the
> lightest 10-5% and darkest 90-95%.

The compression of shadows you are seeing is similar to what I have
observed.  Again Roy will need to comment on the BPC.
> 
> At the time I'm writting it I'm just getting a bad doubt : should the
> PM5 file first be feeding the "QTR-Linearize-data" and the after get
> the "whatever-out.txt" dropped to "QTR-create-ICC" ?

I am not sure what you mean by the above but you should first print a
unlinearized greyscale and measure it with MeasureTool and use the output to
run QTR-Linearize-Data.  Then add the linearize function to the ink curve
descriptor file.  Print a greyscale again with the now linearized curve and
re-measure with MeasureTool.  Use this MT output to run QTR Create ICC.

Steve