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Re: Making SWOP TR001 compliant proofs
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Re: Making SWOP TR001 compliant proofs

Chris McFarling wrote:

So it's possible for two vendors to submit a proof to a customer with each
claiming that their proof is SWOP compliant, although each of the proofs may
be significantly different visually?



"Significantly" is the interesting term here. I am sure that the SWOP people would not agree that there is a "significant" difference. I think they would say that it is a "close" match.

Now the question is...If two colors are "significantly" different what is that equal to in Delta E? What Delta E is equal to "close"? Should the tolerance be less for colors near the gray axis than more fully saturated colors?

Until the industry agrees on standard international units of color measurement and methods of tolerancing we will continue to talk in circles. If we are going to have standards they must be based on objective measurements.

In experiments it has been shown that viewer metamerism can account for differences as high as Delta E of 5. This means that you can have two non-color blind people that are viewing side by side color patches under D50 light and choose adjustments for a match that differ by as much as Delta E of 5.

I would suggest that you measure 50 sheets at the beginning of a press run and then 50 in the middle and 50 at the end. Now see what the variation is with your run. Next measure a standard target placed top of your press sheet and then another at the end of the sheet. This might change your expectations about how tight the tolerances should be. Of course we would have higher standards for proof consistancy than on press.

Ray




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References: 


 >Re: Making SWOP TR001 compliant proofs (From: Rich Apollo <email@hidden>)


 >Re: Making SWOP TR001 compliant proofs (From: "Chris McFarling" <email@hidden>)


 >Re: Making SWOP TR001 compliant proofs (From: "Chris McFarling" <email@hidden>)























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