Re: CMYK to Process pantone spot.
@ John
HA HA HA HA HA -- phew, now THAT was a funny post. really got me laughing on that one..
you wrote;
"No one seems to have noticed Pantone's FAQ that suggests using Adobe Photoshop to find the nearest solid color from a CMYK specification:
http://pantone.custhelp.com/cgi-bin/pantone.cfg/php/enduser/std_adp.php?p_faqid=1195
Okay, so perhaps YOU did not noitce a few things about that post;
First, you probably dod not notice the date - 2001 !
"At 12/11/2001 03:43 PM we wrote - "
In 2001, Adobe was still shipping version 3.x of Photoshop, and if memory servers me correctly, there may not have been the proper required LAB values (that John Knoll 'fudged' into the application, never mind that the CMYK values were based on SWOP printing on a number 5 sheet, which no one printed on in 2001 anyway. My point here is that still, today, that specifying a CMYK value for a Pantone book is flawed, as the method that Pantone comes up with CMYK values is based on a single, very controlled print condition that may not be identical to the method used by the print service provider being used on the project.
So, what to do ?
If you have a spot color in mind, call you printer, and ask them the best way to specify it.
Buy the Pantone Colo Bridge fan book (if you do this sort of thing all the time)
http://www.pantone.com/pages/products/product.aspx?pid=293&ca=1
BUT -- Many Pantone colors are mixed with White ink in them and colors like rubine and rhodamine - Barbie Pink is a great example .
in some cases like PANTONE 18-2133 TPX Pink Flambé - you cannot simulate the color with CMYK inks on a printing press, so you would have to actually buy this ink and run it on press as a special (spot) color. As well, you cannot simulate this color on an RGB monitor, no matter how well it is calibrated.
Another more common color that people struggle with is Pantone 150 (an orange-ish color) - this color cannot be simulated very well using CMYK inks, but a monitor can represent it fairly closely.
So basically, there are only about 42% of the Pantone library that can be reliably simulated and visually match using CMYK printing
(TR001 SWOP) - if they were to printing using Pantone Hexachrome printing (a 6 color process) this increases to about 89-92% - but this is some tricky business and outside the skill set or equipment possessed by most printers.
Related to simulation of Pantone colors reliably, this requires support of Device N profiles (none of which are supported by Adobe applications)
So, the short answer here is "you really can't do this all that precisely"
Here is a really great article that speaks to the issue of printing Pantone colors on paper, and what lengths one must go to do this.
http://www.graphicrepro.co.za/asp/results.asp?art=7497
Pantone does not publish defined matches from CMYK/RGB to PANTONE Colors.