[cairo] Subtractive API, part 1

Chris Murphy lists at colorremedies.com
Fri Feb 5 08:48:08 PST 2010

On Feb 4, 2010, at 11:36 PM, Jon Cruz wrote:

> On Feb 4, 2010, at 11:41 AM, ecir hana wrote:
>> Just to check if I understood....
>> There is no need of using ICC profile for spot color, as long as I
>> could define LAB fallback, right?
> For some workflows it *might* be ok... but for others it may not. And there is always the theoretical case where one measures the same LAB for Pantone 7489 and for Resene M73-080-131, yet runs their print job with those as separate spot inks.

Since there isn't a case of embedded NCPs, I think this is just simple metadata. You don't need a giant profile attached to one spot color just to define what it's supposed to look like.

>> And if we assumed CIE LAB D50
>> (because of ICC?), like:
> I've not seen that D50 is to be assumed due to ICC. I have many ICC profiles with other white points.

The PCS is assumed to be D50. Media white point may be something else. This is why display primaries must be D50 adapted if the display white point is not D50.

Chris Murphy
Color Remedies (TM)
New York, NY
Co-author "Real World Color Management, 2nd Ed"

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