A proof is one that is produced according to the specifications of the latest revision of the proofing standard ISO 12467-7 and is within the tolerances of this standard. The current revision is ISO 12647-7:2016, which has been tightened even further with this standard and has been supplemented by a certified edition of spot colours such as PANTONE and HKS.
But what makes the certified proof cheap? That’s the low price. Proofs are printed on certified proof papers on very high-quality pigment inkjet printers, usually using expensive proofing software, and measured with spectrophotometers. So how can production be done cheaply here?
One litre of ink for proofing devices is around 400 EUR, so it makes sense to use inexpensive alternative ink from China. The problem: there are no manufacturers – neither in China nor anywhere else – who produce inks that would actually produce similar inks in terms of pigment colour and spectral composition. I once called a manufacturer who advertises that his – already quite expensive – inks could also be used for proofing. When I asked him, he said: “No, no, that’s just for advertising, but of course I would never do that or recommend it, and I don’t know anybody who does that. As for the China inks, he said: “They start at 20 EUR per liter, but you get a different ink with every delivery, depending on where the wholesaler buys. Then they have to re-measure the proofer every time… forget it.” In addition, replacing a clogged print head costs around 2,500 EUR, so the risk is too high. A real proof therefore only works with original, very expensive ink.
GMG ColorProof, EFI Fiery XF and ORIS Color Tuner are just some of the most important proofing solutions on the market. What they all have in common is that proofing software is rather a niche software, so the programming effort is very high compared to the sales figures. Depending on the size of the output device and the range of functions in terms of verification, spot colour display or proofing on special materials such as transparent foils, etc., the software costs between 5,000 and 10,000 EUR, and in combination with other software products from GMG or Colorlogic it can quickly cost considerably more. Although there are a few low-cost solutions here too, these are usually irrelevant in professional proofing, as they are either not suitable for more than one workstation, or important functions such as spot colour libraries etc. are missing.
Today a customer called who wanted to order a proof of several HKS N spot colours on an uncoated paper. “Which proof profile should I choose? And how exactly can you match my special colours in the proof? I probably have to proof several HKS N red tones in comparison. By the way, the printing is to be done on Fly Cream, a slightly yellowish paper.”
First of all, I searched with the customer for the production paper in our paper white database. A quick look via full text search revealed that we have measured Fly Cream from Papier Union:
With a B-value in LAB of 9.2, Fly Cream is really not just a little yellowish, as the customer said, but clearly yellowish, chamois, creamy … whatever you want to call it. So it was natural to check the proof profile “ISOUncoatedYellowish”, Fogra 30, to see to what extent the paper white could match.
Together with the customer we looked up our “paper white of proof profiles” table:
Contrary to the customer’s expectations, the paper white of ISOUncoatedYellowish is not even as yellowish as the paper white of the edition paper Fly cream, which is more yellowish by more than 5 steps on the B axis. So it was clear: PSOUncoated as a brighter-free uncoated paper proof standard is clearly too white, ISOUncoatedYellowish is much more suitable.
As is well known, elections are always around the corner, and the trend towards ever larger and more numerous election posters is unbroken. In the past, only Mother Nature made the landscapes colourful in spring, but today every local, state, federal and European election does so easily. Every candidate, every large or small party now has the technical and financial means to transform entire streets into a colourful sea of messages and faces. Once the photographer has captured the election candidates well in the studio, the pictures go off for retouching and then for layout.
Until a few years ago, election posters were usually produced in classic offset printing and then glued onto hardboard with paste, drilled or screwed onto roof batten stands and then attached to street lamps with wire. And if the election took place in the summer, the posters were printed in a double edition, so that in an emergency the faded prints could be pasted over and refreshed with new ones after one month for the final spurt.
Today, however, the corrugated plastic poster is becoming more and more popular, as it is supplied pre-drilled and ready to use, retains its colour for several months and can be attached to street lamps with cable ties. But how should print data be created and how should data be prepared and proofed?
Corrugated plastic posters are produced on different systems. Sometimes four colours are used, sometimes six, sometimes more colours. Therefore, there are no binding proof standards for most digital print products produced in this way.
Instead, it works the other way around: Since most of these digital printing systems have at least the colour gamut of offset printing on picture printing paper, these printing systems are based on the established colour gamut of ISOCoatedV2.
For example, Printpartner-XXL writes: “For colour-critical motifs, we therefore recommend a prepress proof on the original material or the delivery of a colour-binding proof (with media wedge and date). Data that is delivered without colour information is provided and produced with the standard profile “ISO Coated v2”. In such a case, a colour complaint cannot be accepted.
Eine Reklamation der Farbe kann in so einem Fall nicht anerkannt werden.
From our point of view, most printing specialists demand ISOCoatedV2, some like flyeralarm and wir-machen-druck ISOCoatedV2 300%. Some want black exclusively as pure black, some exclusively as CMYK 50/50/50/100 colour black … and some do not give any information about the required colour profiles … but if you don’t specify anything, you probably won’t stick to anything … so if you want to be on the safe side, you should choose a supplier with a functioning colour management system and specifications for colour profiles.
In general, the paper white in a proof is precisely defined in the proof standard and is also measured in every test report.
For PSOUncoated it is 95.00 / 0.00 / -2.00 in CIELAB and for PSOUncoatedV3 it is 93.50 / 2.50 / -10.00, i.e. slightly darker (93.50 instead of 95.00 for brightness L) and significantly bluer (-10.00 instead of -2.00 on the B axis, i.e. the blue-yellow axis in the blue direction).
Recycling papers differ not only greatly from type to type in the area of paper white, but even from batch to batch. So if a printing company orders the same recycling paper in January and in February, the paper mill may well deliver a slightly different white value of the paper, as the paper white of course depends strongly on the recycled paper qualities used for production.
A colour-binding proof for recycling paper is therefore not possible, as no standard has ever been worked out due to the different paper qualities and white tones.
It is recommended for the proof to choose a classic proof standard such as PSOUncoated / Fogra 47, which shows a rather neutral, unbrightened paper white in the proof. Place one side of the recycled paper next to the proof and mentally transfer the colour of the proof to the white tone of your recycled paper. This way you can imagine the later printing result quite well.
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:
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”.
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.
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.
It has taken almost a year, but we are all the more pleased now: The “CIELAB HLC Colour Atlas” is completed and can be ordered in our shop. The HLC Colour Atlas is a open source, high-precision colour system based on open standards.
The CIELAB HLC Colour Atlas offers professional users of colour three decisive advantages:
The Proof GmbH provides proofs for Scheufelen Heaven 42 papers on the new EFI 8245 OBA proofing paper. With this new proofing paper it is now possible to proof the bright-white paper dye of Heaven42l.
With Heaven 42 a bright white paper was developed by the German paper company Scheufelen, which opened up a new color whiteness. Especially technical motifs (shades of gray, silver tones from 4c, strong contrasts) act on Heaven 42 particularly brilliant and neutral. With an unchanged separation (eg with ICC profile “ISOcoated_v2”), but the printed image with the same color and dot gain looks considerably colder. Using images with warm tones (z. B. skintones) it is therefore recommended to do color adjustments.
We proofed Heaven42 on EFI Proof Paper 8245 OBA with optical brighteners and measure the Proofs M1 standard with consideration of optical brighteners. The proof can be provided with a UGRA / FOGRA media wedge and test report. Our Heaven42 proofs provide a good simulation of Heaven42 offered by Scheufelen for the ICC Profiles of Heidelberger Druck. The profile can be downloaded from the Scheufelen Website with additional notes from Scheufelen to pressure requirements etc., which are also included in the download of the profile.
Scheufelen offers two ICC-Profiles for Download, we are proofing the profile of Heidelberger Druck (“_HD”).
Ink Coverage: ~280 % (U)
Black: GCR , 80 % (G)
Max Black: 98 % (K)
Proofing Substrate: EFI Proof Paper 8245 OBA Semimatt
Verification Profile: Made from Reference Data
Verification Light: M1 with OBA
Heaven 42 Proofs can be ordered directly in Proof store of Proof.de. Simply select the profile “Heaven 42 (Coated OBA)”.
Our telephone support often asks for a proof on production paper. Unfortunately, we always have to answer the question negatively. I would like to briefly explain the reasons for this in the following article.
Proofing on production paper is still technically impossible.
All proofing systems currently certified by Fogra are based on an inkjet printer as a test printer, mostly from Epson, Canon or HP. These printers are characterised by a large colour space, good resolution and excellent homogeneity and colour stability – all characteristics that are absolutely necessary for a proof printing system. The Epson systems used by the majority of proof printers are based on 11-colour pigment inks, which can reproduce a significantly larger colour space than e.g. ISOCoatedV2. However, the prerequisite for this is the use of special papers optimized for inkjet printing, in which the pigments and inks are optimally emphasized. This requires special coatings that are optimized for optimum reproduction, fast drying, good abrasion resistance and high UV stability of the print. On an image printing paper without these coatings, the ink would run, hardly dry and would not be smudge-proof. The color space would also be impossible to achieve. A proof would therefore not be possible from this point of view. (more…)
It is actually quite simple to have proofs made. But experience shows that many customers often stumble over the same mistakes. We have put together the ten most important steps towards a successful proofing job:
In the following we would like to present these individual points in more detail.
The Moiré effect, or in other words a halftone screen overlay, is a common phenomenon when viewing prints. It occurs when two even patterns overlap unevenly.
Moire is always created when screens overlap. Typical examples:
The default was:
We have looked into this question: UPM EcoPrime 76 H is printed on web offset paper in a large print shop. The information of the customer service there was:
EAN codes are standard on every product today. While in the good old days, shopowners themselves typed the prices into a cash register by hand, today scanner cash registers are the rule, which scan standardized EAN codes with a laser and thus clearly recognize the article and add it to the receipt.
EAN, by the way, stands for “European Article Number” and was replaced in 2009 by the global GTIN, “Global Trade Item Number”. The EAN or GTIN is a barcode that can be read automatically and read by barcode readers.
For graphic designers in Europe, two standards from the almost infinite number of EAN codes in use worldwide are primarily important in the product area. EAN 13 and EAN 8, i.e. a barcode of either 13 or 8 digits. What do these numbers actually mean?
For some years now, the possibilities of colorimetric measurement of printing inks have become simpler and cheaper. And so it is often believed that measuring printing inks is simple, inexpensive and, above all, highly accurate. And this also across a wide variety of brands and generations of measuring devices. Is that true?
If you look at a few studies, that does not necessarily seem to be the case. IFRA, for example, requires that when measuring BCRA ceramic tiles the colour differences between different measuring instruments should be below Delta-E 0.3. In reality, however, things looked different. In a Nussbaum study, 8 out of 9 measurements were for a Delta-E greater than 2.0; in a Wyble & Rich study, the deviations were between Delta-E 0.76 and 1.68. But why are the deviations so large?
On the one hand, the measuring instruments differ in the way they illuminate the surfaces to be measured. This is important in two respects: On the one hand, measurements can vary greatly depending on the material, for example, because light is emitted and measured from only one light source onto the measuring surface. If a measuring instrument has only one lamp, which, for example, radiates at an angle of 45 degrees onto the measuring surface and whose reflection is measured, then the measurement can deviate by up to Delta-E 3.0 if you only rotate the measuring instrument about its own axis. If a left-handed person and a right-handed person measure the same tiles with the same measuring device, then just by holding the measuring device differently and by the different lighting angles of the tiles a measurement can be completely different.
The solution for this: In a measuring device, several light sources are distributed or, in the best case, the illumination is emitted directly circular at an angle of 45 degrees in order to minimize such effects.
Especially in larger companies today the layout in RGB is the rule rather than the exception. The advantages are obvious:
In practice, however, there are two potential problems in particular.
Problem 1: CMYK conversion in the last step.
The catalogue is designed in InDesign, all data is perfectly matched, the last step before printing and proofing is the export to a printable PDF in CMYK. Usually this is done via a preset in InDesign, which defines the exact specifications for the color space conversion. In practice, however, this color space transfer can hardly be monitored. The problem: Even if you check the color values in Acrobat in the exported PDF file, for example, Acrobat does not really display the colors it contains. Acrobat brav would show you CMYK values even if the RGB images are still wrongly contained. However, other CMYK values can occur during printing when the data is processed again. Lately it looked like this:
There are many possible reasons for a deviation between the proof and, for example, the monitor display:
In general, no patent remedy can be given for the correct display of proofs for the monitor. However, if a proof is provided with UGRA/Fogra media wedge CMYK V3.0 and test report, the chances are high that it reproduces the required colors very precisely. If your monitor image does not correspond to the proof, the error usually lies with you. The list of causes above can help you in troubleshooting.
A proof is a standardized product. Take the classic ISOCoatedV2 proof, for example; the standard proof for coated printing paper. Here is the definition in brief:
Metal is printed with a varnish. Neither the colour of the metal of the tin can nor the colour of the lacquer is clearly defined, nor the thickness of the lacquer application and the printing process in which the lacquer is applied (digital print / screen printing, pad printing etc.) is defined.
A contract proof refers to very tight tolerances and precisely defined framework conditions. This includes not only the densitometric and colorimetric reference of the printing ink, but also, for example, the paper white, which is simulated very precisely in the proof. For exactly this reason there is no proof for recycled paper: The papers and paper whites are simply so different that no uniform, standardized “color” of a recycled paper can be defined. From classic recycled paper with a neutral grey or yellowish-grey colouring to de-inked, almost white recycled papers, everything is available on the market. Just not by default.
Therefore, a proof always refers to offset or gravure printing under standardized conditions. Changed surfaces such as metal or changed paper colours such as recycled or high-quality image papers with inclusions or printing on coloured papers have not yet been standardised and therefore cannot be proofed.
The question often arises why when creating a PDF-X/3:2002 file in Adobe Acrobat, white lines often appear in the preview when there are no lines at all in the file.
The answer is simple: In contrast to current PDF printing standards such as PDF/X-4:2010, which is exported as PDF 1.6 standard, the PDF-X/3:2002 standard often required by printers uses PDF format 1.3, in which transparency is prohibited. As a result, when you create drop shadows in Adobe InDesign, for example, they are converted into rectangular images. If such drop shadows are still used on background images, the white lines appear, which run horizontally and vertically through the PDF at the shadow points. But why do these lines disappear in print and are not visible in other applications like MacOS Preview?
Acrobat has a preview that applies anti-aliasing to vector elements to make edges as smooth as possible. However, this setting also affects paths and masks that are not actually visible at all. The pixel images of the reduced transparencies are therefore slightly blurred. And this is exactly where the white lines of the blur appear, which are actually zero in size and therefore disappear when printed on postscript-capable printers. Not PS printers partially print the screen display, whereby the lines remain disturbingly.
Most graphic artists know the effect, have postscript printers and simply live with it. However, if you are very annoyed by the white lines or if they also appear in the printout, you can simply switch off anti-aliasing in the Acrobat preferences. Under Acrobat > Preferences > Page Display you can simply deselect the checkbox “Smooth vector graphics”. This makes the edges of vector data slightly more pixelated, but the white lines of anti-aliasing disappear immediately.
Proofs are standardized products that are created and tested according to a certain set of values. This is exactly the point that distinguishes them from any “colourful printouts”.
Specifically: A proof for coated printing paper is produced according to the standard values of ISOCoated V2 (paper type 1 and 2, glossy and matt coated image printing, dot gain curves A (CMY) and B (K) from ISO 12647-2:2004) and checked according to a set of values (FOGRA39L). A proof for uncoated paper (e.g. PSOUncoated or ISOUncoated) is produced and checked according to completely different value sets. Logically, because a print on uncoated paper looks definitely different in terms of colour and white value than a print on picture printing paper.
A proof must therefore always be prepared according to a standard and be verifiable according to a reference value set. A list of the current Proof Profiles (as of 2012) can be found here.
The problem: Many printing processes such as digital printing on a color laser or printing on a large format printing system (LFP) are not standardized and therefore there are no valid profiles and specifications.
So what to do? The most frequently used standard has established itself as the “de facto basis”: ISOCoated V2.
This is understandable, because colour-critical prints, catalogues etc. are mainly produced in offset printing on picture printing paper and are therefore subject to this standard. It is therefore generally assumed that a digital printer or an LFP printer, for example, should follow this standard and at least achieve this colour result.
So if you need to make a proof but don’t have the exact details of the profile you need, proof ISOCoated V2, which has become the industry’s most widely used standard and will always be accepted as the basic proof.
Unfortunately, a proof without a profile cannot be produced, because that would just be “colored paper from a proofing system”, but not a valid, ISO-compliant proof.
Since 2009 PSOUncoated has been the standard profile for uncoated paper. Nevertheless, proof service providers often have the problem that at first glance proofs on PSOUncoated often differ significantly from the print result. Immediately visible: the white point of the paper.
The PSOUncoated paper white looks very grayish. If, for example, PSOUncoated is proofed on an EFI 9120 XF paper, which actually has a neutral white coloration as paper, then the paper must be recolored by the printer in terms of paper white. This paper-white simulation makes the proof look “grayish” and often not “bright white” like the real production paper. “I can’t put this down to my client” proof service providers often hear from the agencies and designers who commission proofs. And frankly, printing on bright white uncoated paper will also differ significantly from the PSOUncoated Proof result depending on the paper selected.
Some proofing services still proof uncoated paper according to ISOUncoated, because the paper tone is much whiter and not so grayish. In the medium term, however, this will not overcome the misery: PSOUncoated is the current standard according to which the process standard for offset printing certified print shops are also based. But in the pressroom the differences between norm and reality often become apparent. If the new D50 standard light according to ISO 3664:2009 with higher UV components is used for inspection at the printing table, then proof and printing result can often only be matched very poorly. And due to the long standardization periods, this problem will continue to accompany printers and proofing service providers for quite some time to come.
Colour is colour, you’d think. That’s right. But have you ever tried to explain the colour of your new car or your new red wallet to a friend on the phone? You will notice that human colour recognition and the reproduction of the same in another medium is very difficult.
The same applies to computers – better: monitors, and printers – i.e.: laser printers, inkjet printers or newspaper printing or offset brochure printing.
Why is the red on a monitor different from exactly the same red printed on paper? It’s simple: put the paper in front of the monitor. The two shades of red are exactly the same. Like this. And now you’re completely darkening the room. What do you see? The red on the monitor is still red. And exactly the same red on paper? This is black now. Why is that? Very simple:
A monitor adds light, i.e. spectral components, to the existing ambient light. If you see red on a monitor, it is because the monitor actively emits red light.
And now the paper: When do you see red on paper? Exactly when white light falls on the paper, for example through a window or a lamp. And when do you see the colour red on paper?
When white light falls on the paper and the paper extracts the non-red spectral components from the white light and reflects the red light. That’s when you see the colour red.
One colour, two completely different ways of production. And this is exactly where the colour calibration and the proof start. The strategy? Fairs. And this under fixed conditions and not with the human eye, but with “incorruptible” technology.
Put simply, a monitor calibration device can measure your monitor and see exactly “how much” colour your monitor can display, and “how wrong” your monitor can display colour. And if your computer knows that, it can correct the monitor.
Another measuring device can emit neutral white light onto a paper and measure the reflected colour. Depending on the printing process and paper, the ink looks completely different, but the meter again sees “how much” ink the print can represent and “how wrong” the print represents ink. And if your computer knows this, it can correct it. And:
If the computer knows the colour representation of the monitor and printer, it can correct and adjust the representation so that both correspond to the same colour. Of course, this only works if the colour and brightness of the light that illuminates the paper is also known and standardized.
And how does the proof work? Very simple:
If a computer also knows that the final printed product is to be printed in offset on an image printing paper, and it knows the colour representation of this printing process, then it can simulate this on a monitor and on an inkjet printer.
On the monitor, this colour-accurate representation is a so-called “soft proof”, the colour-accurate preview of the subsequent print on the inkjet printer is called “Proof” or “Contract Proof”.
This inkjet printing must be very precise and meet the highest demands in gamut and colour simulation. And since the image processing technology, colour matching calculation and measuring technology behind it is not very cheap, proofs are still mostly “expensive” inkjet prints. Due to new printing systems and inexpensive and better measuring technology, however, prices have also fallen significantly here in recent years.