QTR-Quadtone RIP

ferdinand_paris wrote:
> I've done a little testing in Qimage to see how using its CMS compared
> to converting first in PS to my newly created custom (rgb) profile,
> and then printing via Qimage with CM off.  Results (PS histograms of
> Qimage print-to-files) are:
> 
> 
>      http://www.ferdinand-paris.com/BPC-Qimage.png
> 
> There's certainly something very strange going on in Qimage if you
> convert to a QTR profile with BPC on.  BPC OFF looks better, but not
> perfect.  
> 
> @Ernst: is this what you were seeing?  Is it worth provoking the
> Qimage list again?  It almost looks like it's not a perceptual
> conversion (which it was definitely specified as).

Yes. that's what I see today and what I have seen in the 
past. But I just measured the greyscale wedges and checked 
the numbers. For the BPC ON in Qimage you will see it in any 
B&W print without checking numbers.
I have checked color printing the same way and it is alright 
so I have no clue what this is.

It isn't so long ago this has been discussed with Mike and 
Roy in this list and I do not know whether it has sense to 
go for that discussion again. There's another thing: all my 
Qimage work is in a one way direction, edited files go from 
Photoshop to Qimage for printing only and they are deleted 
after that. The editing, softproof etc is all done in 
Photoshop where the file to be archived will be saved on 
that system in 16 bit. So if I have to do the P2P for a B&W 
file on Photoshop before sending it to Qimage it isn't more 
work and I have to use a separate setup for Qimage + the 
Z3100 driver for B&W work anyway, can't nest B&W images + 
Color on the same print page there either. The B&W images I 
have are 16 bit scans of B&W frames, in Photoshop they are 
kept at 16 bit when converted to the QTR printer profile, 
after that brought back to 8 bit as Qimage's input is 8 bit. 
There could be a difference in that aspect of 16 and 8 bit. 
Qimage will make RGB files of RGB and Greyscale files even 
if they go to the ABW b&W mode of my Z3100 or if ones sends 
the Qimage output to QTR. That could be the other thing. Not 
just the curve being different in shape but the smoothness + 
the spikes .

Be careful with image files brought back to Photoshop to 
compare their tone range, Photoshop's CM is almost always 
interfering even if it is set to OFF.


-- 
Met vriendelijke groeten,  Ernst


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