Datacolor User to User Support Group.

I subscribe to StudioPrint rip forum and a member tested drydown with Epson Ultrachrome/
Cone's Quadtone inks on PhotoRag.

If you have Excel, here's his findings:

http://d40.yousendit.com/F/2UZZ6UCIL4WGK2J8SG7K2N9ZME/Drydown_PhotoRag.xls

On the bottom of the window are tabs to change inkset results.

His findings suggest that 36 hours is needed for ink stabilization. Also Cyan takes the 
longest time to stabilize.

My question is with delta values: Is there a minimum delta value that is visible to us humans?

--- In colorvision_group@yahoogroups.com, "John Vitollo" <jvlist@...>
wrote:

> My question is with delta values: Is there a minimum delta value
that is visible to us humans?
>

Yep ... delta of 1 is supposed to be visible to the average observer.
 There are people who can see a delta of 0.5 (good vision!)

In a message dated 3/17/06 11:38:06 AM, jvlist@... writes:


> My question is with delta values: Is there a minimum delta value that is 
> visible to us humans?
> 

Thats how delta-e values are defined: with the smallest change perceivable to 
the (typical, healthy) human eye under a specific set of conditions to be 
defined as one delta-e. These conditions are for colors in the 2 degree area of 
our most accute vision, patches seperated from each other, not touching. 
Seamlessly touching colors could be distinguished to less than a delta-e (say half a 
delta-e), moving a square of one color around on screen, on top of a patch of 
another color, adds motion to the mix, so perhaps a quarter of a delta-e 
could be distinguished. But earlier delta-e forumli are not perceptually uniform, 
so   newer attempts to get the level of difference to reflect what the human 
eye can distinguish more closely throughout the colorspace have been created. 
At the moment the most reasonable compromise is Delta-e94. Anything thats 
fractional in Delta-e94 can pretty much be ingnored. 

So, for instance, reading all the patches on the same Color Checker with a 
new EyeOne spectro, and a DC 1005, then calculating delta-e 94 values for all of 
them shows an average difference between the EyeOne and the PFP spectro of 
less than a delta-e94... so I'd say pretty much ignorable.

C. David Tobie
Product Technology Manager
ColorVision Business Unit
Datacolor Inc.
CDTobie@...
www.colorvision.com