Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Ernst Dinkla <edinkla@...> wrote:
> 
> Like Mark already mentioned:
> Be aware that the HP Vivera numbers are taken from a color test target
> printed in color mode and the patch measured may have a different value
> in density-tone than the Midtone L*=50. It is also done on the HP Smooth
> Fine Art which in the rolls I got was slightly warmer than Photorag. All
> the other printer-inks use a B&W mode for printing on Photorag and
> measure the same patch. Nevertheless it is good that Paul included it
> in this list. In the Z3100 neutral grey inks are replacing any hue mix
> when neutral patches are printed, from 0-100%, even in color mode Color
> profiling in color mode could however mix in a hue ink. I don't think
> that a B&W workflow would change the test numbers but it could....

Yes, and perhaps I should stress this again as well.  It is highly likely that a monochrome test of the Hp inkset will improve the summary stats significantly for the better which is why I took the time to point out that the Hp sample data is excerpted from an AaI&A color target test sample whereas the other data sets are derived from AaI&A monochrome targets. Hence, I want to make sure that people looking at this excerpted data don't try to rank the Hp sample along with the others based on the summary stats. The summary stats are calculated on average system response and worst 10% response of all 30 patches.  But the Hp test is averaging an array of colors (mostly the 24 macbeth colorchecker chart colors), whereas the other samples are averaging 30 patches of "gray tones".  Thus, we can't make the summary stat comparison fairly.  The Hp photogray inks generally outperform the other Hp colorants in the full HP Vivera pigment inkset (pretty much true for all the latest pigment sets from Epson, Hp, and Canon). Hence, a test sample printed solely in a B&W mode (like the other samples posted here) is very highly likely to boost the Hp summary scores for this paper.  In fact, the Hp sample has actually reached the 90 megalux hour exposure dose in test (it has been in test longer than the others).  And at the 90 megalux hour mark, all seven neutral patches in the AaI&A color target are still turning in 100% I* color scores with the HP Vivera pigmented ink. That means no hue shifting whatsoever has been detected.  Hp has clearly engineered a superbly "balanced fade" set of inks. This is good. 

The value proposition of the full AaI&A test reports is that you can also discern important paper/ink interactions. What's dragging down the summary stat scores in this posted Hp sample is the pure magenta and also the violet-purple color patches. Yet if one prints the same inkset on another paper the most affected colors can be different. On Crane Museo Silver Rag paper, for example, the orange color patch takes the biggest hit (presumably created with at least some of the Hp Z's red ink perhaps in addition/replacement to magenta and yellow inks). 

Bottom line: ignore the summary stats for the HP sample in this set of excerpted samples and just compare the single midtone gray patch response to the other samples. That said, it is fair to look at the summary stats for the others. Also, please take the time to study the full reports if you want to learn even more about ink/paper interactions.