Digital BW, The Print

Steve,

I sent more detailed comments directly, but see below also:

On Oct 21, 2005, at 9:18 PM, Steve Kale wrote:

> OK I understand but I am not trying to compare my colour managed  
> results
> with Carl's. (I haven't even done an HPR AB&W print using colour
> management.)  I was principally concerned with comparing the GM colour
> profile vs the QTR create ICC profile.  The point was to do a very  
> rough
> cross check on your BPC and to show that the sort of impact at the  
> black end
> of the scale of the QTR Create ICC profile is consistent with what  
> a GM HPR
> colour profile does, ie it would appear to be behaving correctly.   
> (I was
> disappointed the Epson colour driver did not get the same min L* to  
> make the
> comparison more direct.) A great deal of comfort is gained if we see a
> performance consistent with the colour community's widely deployed  
> colour
> management.  Then it is also valid to compare the linearised un- 
> managed
> output (ie the workflow prior to QTR Create ICC) with ICC profile  
> managed
> output - not the actual points (which for two of the charts are  
> influenced
> by my GG 2.2 workspace) but the "general" shape of the TRC. That is  
> to say,
> as expected, colour management compresses the dark end of the scale  
> and
> generally lowers the L* of the TRC.
>
> Re Carl's work, I have simply noted the very tight compression in the
> straight non-colour managed output.  If he is printing an untagged  
> document
> without colour management then he is sending unaltered pixel values
> presumably with the observations he intends.  (My desire to confirm  
> the
> document isn't tagged in  anyway is to ensure that, say, a 95% step is
> actually 95% K etc.)
95% is 95 K, etc., there was no conversion to screw up the numbers,  
but it doesn't matter if the file is tagged or untagged in this  
situation.
>  He observed only a 0.77 difference in L* between 95%
> and 100%.  My Adv B&W printout (without colour management) on the  
> 4800 shows
> an L* difference of 3.08 between 100 and 96 and 4.7 between 100 and  
> 94.
Better driver in the 4800 or MK vs Eboni?
> Hence my question as to his choice of paper setting.  For HPR I  
> used Velvet
> Fine Art and I wondered whether if he used this paper setting the  
> ink load
> etc may provide less bunching in the dark end.
I also used the VFA setting.
> This isn't anything to do
> with colour management but rather the basic performance of the 2400  
> Adv B&W
> driver.  BTW Carl I am using Eboni in the K slot which I think is  
> another
> difference.  I agree our colour managed observations are not  
> comparable
> because of the different workspaces.  His 50% patch would be  
> seeking an L*
> of 50 vs my 54.
>
>
>
>> From: Roy Harrington <roy@...>
>> Reply-To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>> Date: Fri, 21 Oct 2005 22:57:51 -0000
>> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>> Subject: Re: [Digital BW] ICC v. Transfer Function in Epson driver
>>
>>
>> I hate to beat this to death but once you select a printing
>> profile in the Print with Preview -- there is NO SUCH THING
>> as UNTAGGED RAW DATA.  If there is no embedded profile it will
>> use the Working Gray Space.  It has to have a source profile in
>> order to apply the print profile.  It's never one-sided.  There
>> no such thing as converting a raw file into a print profile.
>>
>> So if you guys compare results when printing with ICC profiles
>> the source profiles make a difference and if you see Untagged
>> then the working space is critical.
>>
>> Roy
>>