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one hand, the obviously wrong profile conversion of the print shop with InDesign CS2 to “US Web Coated”, a completely outdated profile never used in Europe, which was delivered with early Creative Suite versions and was probably never adapted due to a lack of competence on the part of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.

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PDF/X4 – The future of PDF/X?

The PDF/X4 standard, a new PDF specification for PDF export, has already been available for several years. But what are the advantages of PDF/X4?

Users from the print sector have known the ISO PDF-X standards for many years. If the name PDF stands for “Portable Document Format”, i.e. the portable and thus transferable document, PDF “X” is a version specialized for “eXchange”, i.e. the exchange of PDF files. In concrete terms, this means that many of the functions that a PDF file can potentially display (form fields, calculations, 3D elements, films, etc.) but which cannot be controlled in print are prohibited in PDF/X in order to ensure secure data exchange.

While PDF/X2 hardly came into its own, PDF/X1a and /X3 are still the standards for the printing industry today; almost all online printers such as Flyeralarm etc. demand PDF files in the PDF/X-3 standard. Why? The PDF/X-1 and PDF/X-3 files offer many advantages to printers: Instead of open data from Quark XPress or Adobe InDesign, the PDF significantly reduces the workload for print shops. No native software is necessary, no fonts, no image links… all this used to cost time and money. And to round off the PDF, the X was added, which stood for production reliability, since only those things were allowed to be used in the PDF that could also be safely exposed and printed.

However, one of the biggest disadvantages of PDF/X-1 and /X-3 so far has been the lack of transparency:

  • Pictures were broken down into many small tiles, and were therefore no longer editable afterwards
  • Text was partially converted to paths if it was below transparent area, the editability of the PDF file was also obsolete here
  • Customers complained about the white lines in the PDF, a display error in Adobe Acrobat based on the tiling of lines.
  • The transparency reduction color space, i.e. the color space into which the transparencies were converted during PDF export, could only be set globally. Either CMYK or RGB. A media-neutral workflow was therefore no longer possible.

However, the new PDF/X-4 standard (ISO 15930-7) has also been available for several years. The PDF/X-4 standard can be used as of PDF 1.5 and also allows transparency, for example, so transparency reduction is no longer absolutely necessary. The PDF file becomes slimmer, images are no longer tiled and therefore also well represented and latest changes in the PDF file are possible for both images and texts. Since text also remains text, the full text search for PDF files is possible at any time. And: Due to the availability of Lab, RGB and CMYK data and the elimination of transparency reduction, a media-neutral workflow with all common color spaces plus spot colors is also possible.

PDF creation has also been simplified in recent years. Due to the elimination of the postscript intermediate stage with subsequent processing via Acrobat Distiller, PDF files can already be generated directly in the layout programs for a long time. And that again causes the omission of PPD files and much more.

Since InDesign CS3, PDF/X-4 documents can also be created here. Since version CS 5.5 ff the current PDF/X-4:2010 specification is also available. This means that the current standards of PDF/X-4 and PDF/X-4p are each based on the PDF 1.6 standard. PDF/X4-p refers to external color profiles, contains all data, the file is called PDF/X4, which has increasingly established itself as the standard and has also been demanded as PDF/X standard in the final examinations for media designers for three years. PDF/X-4 supports color management, Lab, CMYK, RGB, grayscale and spot colors. Transparencies and JPEG 2000, 16-bit data and OpenType fonts are also allowed.

PDF/X-4 actually does much better than the previous standards. And so it is only a question of time when PDF/X-4 will also become widely accepted. Simple and precise creation of PDF/X-4 files is now standard in Adobe InDesign or Quark XPress.

With all the advantages of the X-4 standard, however, the disadvantages should not be concealed

The more color spaces are possible besides CMYK in a PDF file, the more responsibility for the correctness of the data lies with the creator of the PDF, the designer. If you could be sure with the very secure PDF/X-1a printing standard that all data was in CMYK and flattened and that the result is displayed in Acrobat, which will later also be generated in print, then PDF/X-4 is no longer so secure. How many color spaces are included? Are they all correctly marked? Is the output color space correct? Are the transparencies reduced correctly?

Many software manufacturers have promised PDF/X-4 compatibility, e.g. for their RIP software… but only promised. Sometimes, the transparency reduction in the RIP results in bizarre cases, as in this example. In another concrete case from our practice, an RGB black area behind numerous CMYK layers, which should never have been printed to the best of our knowledge and belief, confused the images above it, which were transparently cleared via alpha channel, in such a way that the entire print tore off in a rectangle instead of running out softly on black. And: if the output color space of a PDF/X-4 proof file does not match the ordered proof profile, we cannot reliably proof the file correctly. Instead, we issue a “Data incorrect” message asking you to revise the file with the correct output color space.

This means that the three most important PDF/X color spaces will continue to exist in parallel for a long time to come: PDF/X-1a as the safest printing standard, PDF/X-3 as the most common and PDF/X-4 as the most flexible, but also most sensitive and “responsible” of the three.

What data should I give for proofing?

A proof is suitable for two types of color control: firstly, during the creation or retouching phase, e.g. to reconcile a color retouched image with the original, and secondly to check the final data directly before printing.

For control proofs during the data creation of a project, the data format usually does not matter. Whether PDF, JPEG, TIFF; EPS, PS or even PSD… Many proofing companies accept a variety of data formats. For a correct evaluation of the result, however, it is important to proof in the color space in which the print product is also created later. Data for a letterhead should therefore be proofed in ISOUncoated or PSOUncoated, while products printed on image printing paper should be proofed in ISOCoatedV2. For yellowish paper, newsprint or gravure printing, there are many other profiles for which a proof can be produced. You can find a good overview of the current proof profiles here. It is also important that the proof format and the final print format do not differ too much. Only in this way is a correct check possible.

When the brochure has been laid out or the catalogue production has been completed, a proof should be prepared again for the final check by the customer. This proof is then created with exactly the same data that is also sent to the print shop. This is usually a PDF X/3:2002 file, as this is the preferred data format for printers. If the pages are delivered to the printer with bleed marks and bleed, then the proofs should actually be created in exactly the same way. The finished proofs can then first be used as approval for the customer, and secondly for checking the OK sheet in the print shop. This ensures that no unpleasant surprises wait for the customer (what does the colour look like????) or the printer (why does the customer make a complaint?????) after printing and bookbinding.

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