Why is the embedding of RGB profiles so important?

A few days ago we received a call from a customer in the field of design, who sent open Adobe InDesign data in ISOCoatedV2 300% with contained RGB images to the production company for a complex CD production on the advice of the producing company (“The printing company still has a prepress stage, which can then prepare your data optimally…”). The result of the finished printed CD booklets and inlays did not correspond at all to the calibrated monitor image of our customer, the client was also unhappy and requested the print data about the production company from the print shop responsible for the print to troubleshoot. Data in the “US Web Coated” color space with 350% ink coverage came back from the printer. For troubleshooting, the customer then had a proof of his data created by us, but had chosen the settings “Convert to target profile (retain values)” as usual when writing the proof PDF; we thus received completely CMYK data, of which we produced a proof according to ISOCoatedV2 300%, which completely met our customer’s expectations. So it seems that the designer created the data correctly and printed the print shop incorrectly.

On closer inspection, our error analysis revealed two serious weaknesses:

  • On the one hand, the obviously wrong profile conversion of the print shop with InDesign CS2 to “US Web Coated”, a completely outdated profile never used in Europe, which was delivered with early Creative Suite versions and was probably never adapted due to a lack of competence on the part of the print shop.
  • On the other hand, the open InDesign file of our customer, which he had sent to the production company, contained RGB images without a profile (DeviceRGB), which cannot be safely interpreted.

In this case, a complaint of the designer to the printing company will of course be difficult, as on the one hand, non-profiled RGB data were sent to the production company, and on the other hand, no print PDF generated by the data creator in the correct output color space ISOCoatedV2 300% was supplied.

If this had been done, one could at least have argued that the expected color of the production print would have been comprehensively known. Thus, one can only refer to the fact that the printer would have had to ask the designer for RGB data without an embedded color profile, and should not have assigned the data somehow to a profile “blindly”. The fact that the print shop with its crude US Web Coated workflow certainly did not create a correct print file, but a wrong one for the output, can indeed be stated, but the print shop can always talk its way out to “systems with in-house standard”.

How do we deal with RGB data at Proof.de?

If we receive a PDF file that contains RGB images, the next step is to check if the file is a valid PDF/X-3 or PDF/X-4. If this is the case, we check whether all input RGB profiles are correctly marked with color space (sRGB / AdobeRGB / ECI-RGB-V2 etc.) and rendering intent, then we check whether the correct output color space was used as output intent and whether also contained CMYK data have the correct input profiles. If yes, then we proof the file with the settings: “Consider all input and output color spaces”.

In this case, the file is reproduced 100% exactly as our customer created and defined the color profiles. If he has made a mistake and e.g. marked an image with a wrong RGB profile, this will also be “incorrectly proofed” exactly as correctly.

If RGB data should not contain a profile, e.g. if they are created in Device RGB, we generate a “data incorrect” e-mail in which we explain our procedure as follows:

“Dear customer, the data check has shown that RGB elements are contained in your data. RGB elements can only be safely interpreted in the proof if they are marked with a color profile and a rendering intent. This is the case, for example, with correct PDF/X-3 and PDF/X-4 data. The correct output intent must also be specified.

At least one of these criteria does not seem to be the case for your file. The safest way would be to convert the contained RGB data to CMYK. This has the advantage that you have control over the conversion and can view the CMYK result again in Acrobat before uploading the file again for proofing. We can then reliably use your CMYK values for the proof. To do this, call up the current order in your customer account, delete the incorrect data and upload the corrected data.

If, for example, the RGB element should only be a small image that is not relevant for the overall impression of the proof, or if you do not have another file available for the proof, then of course we can also use your RGB data for the proof. If available, we use your RGB source profiles and rendering intents, otherwise we use the sRGB standard and the rendering intent “relatively colorimetric with depth compensation”, which in most cases will lead to correct proof results. If you would like us to proof the supplied RGB data in this way, please let us know. Please do not hesitate to contact us if you have any questions. Best regards, your proofing team”.

In our case, the CD production case would also not have occurred in the proof, as we reject RGB data not provided with an ICC profile with the error message mentioned above, and do not convert them, as we cannot predict precisely how our customer would have liked the data to be converted.

We are aware that our approach is not 100% the ultimate best approach in all cases, but to the best of our knowledge and belief it is best in line with market practice and the expectations of our customers.

However, we are also happy to accept your individual requirements and circumstances. Give us a call or send us an email and describe your processing requirements.

Colour Management Consulting and Expertise

Colourmanagement Consulting

Colourmanagement Consulting

By the way: We are happy to put our knowledge and data competence at your service: If you also have a problem, a question about print data, data preparation, or – as in the above example – a misprint has already occurred and you need external expertise and assistance for the complaint: Give us a call. We will be happy to advise you and help you where we can help. We will charge you for our advice and analysis at an hourly rate of EUR 90,- plus VAT, and you will be billed for 15 minutes each. An initial consultation and assessment is of course free of charge.

Related Posts

How CMYK and RGB profiles are handled in proofing

When we receive a file from you, the first thing we check is whether there are colors other than CMYK in the file. If the file is built exclusively in CMYK, it will be sent directly for proofing.

Handling wrong profiles with CMYK data / “Profile Mismatch
If we have only received CMYK data from you, we will ignore all input and output profiles and only use the CMYK values that we bring to the ordered output color space.

Example 1: Data in ISOCoated, proof in ISOCoatedV2 ordered, thus wrong or no CMYK profile embedded.

You send a file with the profile ISOCoated and a color area in CMYK 100/70/0/0 and order a proof according to ISOCoatedV2.
We ignore the ISOCoated profile and proof the pure color value 100/70/0/0 according to ISOCoatedV2.

Why do we do this?
In our proofs, we try to reproduce the “lived reality” of the print as well as possible. In many conversations with printers we have seen that in almost 100% of the cases they do not convert profiles from CMYK to CMYK, but instead put a colour value of 100/70/0/0 on the plate without taking CMYK profiles into account, insert paper and print in conformity with the standards. So we also map this way, although it would actually be “more correct” to perform a color space transfer from ISOCoated 100/70/0/0 to ISOCoatedV2. However, this results in a different color value, for example 100/63/1/6 for relatively colorimetric conversion with depth compensation or 100/63/3/15 perceptively with depth compensation!

In practice:

One of our customers did not proof 30 slightly different, dark blue colour areas in ISOCoatedV2 on our premises, but on the premises of a colleague, under each of which the CMYK value was in black lettering, in order to sample the colour of a powder-coated surface. The customer defined a very well fitting CMYK colour value on the basis of the proofed colour areas, inserted it into his brochures and started the print jobs. Result: The dark blue was a distinctly different blue than on the reference proof, customer and agency were very dissatisfied and went on troubleshooting. Now the case came to us.
We received a file for proofing according to ISOCoatedV2 and compared it with our colleague’s proof. The colors with the same black CMYK values printed underneath were clearly different, but both proofs were provided with media wedges and measured correctly. After some troubleshooting, we came up with the idea of requesting the original proof from our colleague, which also existed. In this one there was a Fogra27Coated profile, thus an implementation of the old ISOCoated. A proof according to ISOCoatedV2 had been ordered at that time. Had it happened? The colleague had taken the input profiles into account, which resulted in a significant change in the CMYK values of the color patches, as mentioned above, due to a color space transfer from CMYK to CMYK. The black printed CMYK values under the color patches had of course not changed. The patterned CMYK value therefore did not correspond to the proofed value at all. Our customer fell from all clouds: “How, our CMYK values were not proofed”. This would not have happened with us, because we would ignore the embedded profile with CMYK data. In this case this would also have been our customer’s expectations.
After almost two hours, we had determined the “error” (or perhaps rather: the “difference”), created a proof for our customer that was “in line with expectations”, which he could use to determine the appropriate CMYK value in ISOCoatedV2, and solved the problem. Continue reading