Substrate Relativity Calculator
With papers changing the way they are; most do not fall within the tolerances specified in 12647-2. I like this idea of the Substrate Calculator. My question is this. Let's say we proof to GRACoL tolerances on a paper that is within the specification. We now get a #1 or #2 paper that is out of spec. I use the calculator, create a new CGATS file and create a new ICC Profile. I use CGS ORIS Color Tuner and hone in my proofing device (Indigo press) to within tolerance and proof my files/images on the "new" paper. What have I achieved. I have created a proof that the printer may have an easier time "matching"; but can I say that this proof adheres to GRACoL specifications? If you were to read the 12647 color bar it would pass only if I have the proper dataset loaded to compare to using software such as ORIS Certified Proof. Someone else checking my proof to GRACoL would say it "fails" because they would be comparing to the "original GRACoL". What exactly have I accomplished and how can it be classified as a specification. Mike Stewart
Hi Mike, The purpose of the substrate calculator is to generate more realistic data for non-standard paper. So, IMO, you'd be deviating from Gracol data by going outside the specification, but gaining data that is more realistic given the differences in substrate. A recipient of a proof using this new data may or may not be on board with this deviation, so you should have the conversation up front. Hope that helps, Mike Sent from my iPhone On Oct 17, 2012, at 1:52 PM, Mike Stewart <mstewart@embassygraphics.com> wrote:
With papers changing the way they are; most do not fall within the tolerances specified in 12647-2. I like this idea of the Substrate Calculator. My question is this. Let's say we proof to GRACoL tolerances on a paper that is within the specification. We now get a #1 or #2 paper that is out of spec. I use the calculator, create a new CGATS file and create a new ICC Profile. I use CGS ORIS Color Tuner and hone in my proofing device (Indigo press) to within tolerance and proof my files/images on the "new" paper. What have I achieved. I have created a proof that the printer may have an easier time "matching"; but can I say that this proof adheres to GRACoL specifications? If you were to read the 12647 color bar it would pass only if I have the proper dataset loaded to compare to using software such as ORIS Certified Proof. Someone else checking my proof to GRACoL would say it "fails" because they would be comparing to the "original GRACoL". What exactly have I accomplished and how can it be classified as a specification.
Mike Stewart
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Hi Mike E.- Do you have any idea what it would take for, let's say, a press to be "on board" with this deviation? Would it take something more than already being to spec with the "original GraCol" standard? -Louis On Oct 17, 2012, at 2:05 PM, Michael Eddington <meddington38@gmail.com> wrote:
A recipient of a proof using this new data may or may not be on board with this deviation, so you should have the conversation up front.
Mike, We have now a method to adjust data sets and take into account actual paper color vs reference data set paper color. I encourage you to use this method named "Substrate Corrected Colorimetric Aims (SCCA), validated by Prof. Chung from RIT, and recognized in CGATS 021 and ISO 15339 drafts. Once your data set is adjusted using the actual paper color, you can build your new ICC profile. Kind Regards, Elie Khoury -------------- On Oct 17, 2012, at 19:39 , Mike Stewart wrote:
With papers changing the way they are; most do not fall within the tolerances specified in 12647-2. I like this idea of the Substrate Calculator. My question is this. Let's say we proof to GRACoL tolerances on a paper that is within the specification. We now get a #1 or #2 paper that is out of spec. I use the calculator, create a new CGATS file and create a new ICC Profile. I use CGS ORIS Color Tuner and hone in my proofing device (Indigo press) to within tolerance and proof my files/images on the "new" paper. What have I achieved. I have created a proof that the printer may have an easier time "matching"; but can I say that this proof adheres to GRACoL specifications? If you were to read the 12647 color bar it would pass only if I have the proper dataset loaded to compare to using software such as ORIS Certified Proof. Someone else checking my proof to GRACoL would say it "fails" because they would be comparing to the "original GRACoL". What exactly have I accomplished and how can it be classified as a specification.
Mike Stewart
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Mike,
I have created a proof that the printer may have an easier time "matching"; but can I say that this proof adheres to GRACoL specifications?
when you replace GRACoL with FOGRA the answer is No. Since a proof is intended for a side-by-side evaluation. And the obvious paper difference that you "calculate to 0" is still there when you compare it. you are entering a field which I call media relative colour reproduction (where reproductions are assessed in isolation). And here your approach is valuable. But if you confuse both approaches (Side-by-Side versus media relative) you will enter a lot of problems .... sincerely Andy PS: You might check put the PSD (Process Standard Digital) handbook, where provisions (from print buyer to the service provider) are made for both colour reproduction types. On Oct 18, 2012, at 4:30 AM, Elie Khoury wrote:
Mike, We have now a method to adjust data sets and take into account actual paper color vs reference data set paper color. I encourage you to use this method named "Substrate Corrected Colorimetric Aims (SCCA), validated by Prof. Chung from RIT, and recognized in CGATS 021 and ISO 15339 drafts. Once your data set is adjusted using the actual paper color, you can build your new ICC profile. Kind Regards, Elie Khoury --------------
On Oct 17, 2012, at 19:39 , Mike Stewart wrote:
With papers changing the way they are; most do not fall within the tolerances specified in 12647-2. I like this idea of the Substrate Calculator. My question is this. Let's say we proof to GRACoL tolerances on a paper that is within the specification. We now get a #1 or #2 paper that is out of spec. I use the calculator, create a new CGATS file and create a new ICC Profile. I use CGS ORIS Color Tuner and hone in my proofing device (Indigo press) to within tolerance and proof my files/images on the "new" paper. What have I achieved. I have created a proof that the printer may have an easier time "matching"; but can I say that this proof adheres to GRACoL specifications? If you were to read the 12647 color bar it would pass only if I have the proper dataset loaded to compare to using software such as ORIS Certified Proof. Someone else checking my proof to GRACoL would say it "fails" because they would be comparing to the "original GRACoL". What exactly have I accomplished and how can it be classified as a specification.
Mike Stewart
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Elle: Looks interesting. I believe this to be a spreadsheet - does anyone know where it may be available? Mike Stewart Elie Khoury <eliekhoury@alwancolor.com> writes:
Mike, We have now a method to adjust data sets and take into account actual paper color vs reference data set paper color. I encourage you to use this method named "Substrate Corrected Colorimetric Aims (SCCA), validated by Prof. Chung from RIT, and recognized in CGATS 021 and ISO 15339 drafts. Once your data set is adjusted using the actual paper color, you can build your new ICC profile. Kind Regards, Elie Khoury --------------
Dear Mike, the underlying calculation method was originally developed and tested to predict the colour-deviation of a solid ink when the measurement backing is changed. BTW: For this purpose (solid inks and change of backing) it works very well. Knowing this it is quite easy to understand what you will get from the calculation. If you have a colorimetric description of a print on paper 1, you feed this along with a whitepoint of paper 2 (or the same paper on a different backing, see above) to the calculation method the model will predict the outcome of a print with constant density (remember, originally it predicts backing differences for the same print) on the new paper. So if you used this new dataset for imageseparation and proofing and if the printer printed with the same densities that he would have used for paper 1 you will have a match……… if the method worked. Things to consider: 1) The underlying model makes the assumption that the influence of the paperwhite on the resulting colour is linear from paperwhite to the blackpoint. This assumption is simply wrong. So the predicted colours for everything but the solids is at least inaccurate if not completely off (depending on the inks, the screening…) 2) Is it a good practice to keep the densities that were found to fit perfect for one paper for another paper? 3) With increasing deviation between reference data-set and real-world paperwhite the prediction get's worse. Regarding your question "acc. GraCol": If you ask, if it was according to ISO 12647-7 (this is the international standard for digital proofing), the answer is yes, if the proof is in tolerance when you compare reference printing condition (in this case the result of your calculation) and simulated colour on the proof. But what do you win, if you simulate something in tolerance that does not reflect reality…..? Best regards Claas Am 17.10.2012 um 19:39 schrieb Mike Stewart:
With papers changing the way they are; most do not fall within the tolerances specified in 12647-2. I like this idea of the Substrate Calculator. My question is this. Let's say we proof to GRACoL tolerances on a paper that is within the specification. We now get a #1 or #2 paper that is out of spec. I use the calculator, create a new CGATS file and create a new ICC Profile. I use CGS ORIS Color Tuner and hone in my proofing device (Indigo press) to within tolerance and proof my files/images on the "new" paper. What have I achieved. I have created a proof that the printer may have an easier time "matching"; but can I say that this proof adheres to GRACoL specifications? If you were to read the 12647 color bar it would pass only if I have the proper dataset loaded to compare to using software such as ORIS Certified Proof. Someone else checking my proof to GRACoL would say it "fails" because they would be comparing to the "original GRACoL". What exactly have I accomplished and how can it be classified as a specification.
Mike Stewart
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participants (6)
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Andreas Kraushaar
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Claas Bickeböller
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Elie Khoury
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Louis Servedio-Morales
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Michael Eddington
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Mike Stewart