Digital BW, The Print

I remember I read about it but can not find the thread any longer.

Here is the issue : when I get a file with pure 100% K and then convert 
with QTR-ICC (VFA, HRP...) and then look at the tone scale in the PS 
Level command (Alt-click on XP), the scale is no longer from 100%K to 
white but some kind of dark grey to white.

My interpretation would be that no K will be layed down when printing. 

I know BPC is embedded in the ICC (which reflects by a non pure K but a 
dark grey) but again if no 100% value in the converted file, then no 
pure K is to be sprayed on the paper (?).

Please help or let me have the threat ref please.

Olivier

The curve embedded in a QTR-ICC profile runs from pure black to pure white.
You can see this by looking at one of the profiles.  Therefore pure black is
still mapped to pure black.  The end points should not move.

> From: Olivier <odesmais@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Sun, 19 Feb 2006 15:25:50 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: [Digital BW] QTR-ICC BPC & Pure Black
> 
> I remember I read about it but can not find the thread any longer.
> 
> Here is the issue : when I get a file with pure 100% K and then convert
> with QTR-ICC (VFA, HRP...) and then look at the tone scale in the PS
> Level command (Alt-click on XP), the scale is no longer from 100%K to
> white but some kind of dark grey to white.
> 
> My interpretation would be that no K will be layed down when printing.
> 
> I know BPC is embedded in the ICC (which reflects by a non pure K but a
> dark grey) but again if no 100% value in the converted file, then no
> pure K is to be sprayed on the paper (?).
> 
> Please help or let me have the threat ref please.
> 
> Olivier
>

Hi Steve,

Yes you totally right.
Still, I'm puzzled at seeing that when the Levels/alt+click routine is 
run black is not at pure black. Is this a QTR-ICC issue or a PS one, 
the former one seems the most likely one.

This would still mean the file does not have 100%K values when sent to 
QTR : isn't it strange. Pure Black seems to be mapped to paper blackest 
reproduceable tone at the file level, e.g. the driver does not get a 
100%K value fed in.

Olivier

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale 
<stevekale@...> wrote:
>
> The curve embedded in a QTR-ICC profile runs from pure black to pure 
white.
> You can see this by looking at one of the profiles.  Therefore pure 
black is
> still mapped to pure black.  The end points should not move.
>

So you start with, say, a GG2.2 image file that has pure black in it when
looking at the histogram.  You then convert to a QTR ICC profile, say one
you made for HPR, and then you look at the histogram again and your black
point is not pure black?  That can't be because pixel value 0 is not
affected by the transform in the profile - it stays at 0 and is sent to the
printer at which point it produces maximum black.

> From: Olivier <odesmais@...>
> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Date: Sun, 19 Feb 2006 17:29:38 -0000
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> Subject: Re: [Digital BW] QTR-ICC BPC & Pure Black
> 
> Hi Steve,
> 
> Yes you totally right.
> Still, I'm puzzled at seeing that when the Levels/alt+click routine is
> run black is not at pure black. Is this a QTR-ICC issue or a PS one,
> the former one seems the most likely one.
> 
> This would still mean the file does not have 100%K values when sent to
> QTR : isn't it strange. Pure Black seems to be mapped to paper blackest
> reproduceable tone at the file level, e.g. the driver does not get a
> 100%K value fed in.
> 
> Olivier
>

Ok, Im stupid : it's only if and when I used inadvertably relative 
instead of perceptual that this occured (I use rela(tive for color 
and have left it... no comment). 

Sorry to have bothered.

Olivier

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale 
<stevekale@...> wrote:
>
> So you start with, say, a GG2.2 image file that has pure black in 
it when
> looking at the histogram.  You then convert to a QTR ICC profile, 
say one
> you made for HPR, and then you look at the histogram again and your 
black
> point is not pure black?  That can't be because pixel value 0 is not
> affected by the transform in the profile - it stays at 0 and is 
sent to the
> printer at which point it produces maximum black.
>