Since many printed matter contains spot colours such as Pantone or HKS, the question often arises whether these colours can be proofed at all. The answer is “no”. Only an approximate simulation of these colors is possible.
The reason: Each special ink is a specially mixed, “real” ink and therefore cannot be mixed from the 4 printing inks (cyan, magenta, yellow and black).
Today, modern proofing machines have up to 12 different printing colours and, in addition to the classic primary colours, also have, for example, orange and green and violet as real colour pigments in the machine. Proof printers such as the Epson SureColor P9000V are therefore capable of displaying significantly larger color spaces than, for example, ISOCoatedV2. The spot color simulation in these devices is therefore sometimes very good when controlled via a Contone driver, which can access the entire color space of the proof printer. Epson himself points out, for example, that “98% of all Pantone colors” can be covered. This may be doubted, but a number of over 90% of all Pantone colors is realistic from our point of view.
In the past, Pantone and HKS colors were simply converted by the proofing systems to CMYK and then simulated in the standard color space, i.e. mostly ISOCoatedV2. The representation of the colors here is mostly completely insufficient. For the reproduction of Pantone and HKS colours in a proof it is therefore immensely important to have a modern proof printer with many colours and a high colour gamut and a modern proofing software which is also able to precisely control the printed gamut.
Differences in the quality of the simulation of spot colors can quickly be seen in the different printing systems: If the proofing service provider prints with an older 6-color or 8-color system (Cyan, Light Cyan, Magenta, Light Magenta, Yellow and Black or Light Black), spot colors are simulated worse than, for example, with a modern 11-color system with Cyan, Light Cyan, Orange, Yellow, Magenta, Light Magenta, Photo Black, Matte Black, Light Black, Light light Black and Green.
The higher simulation quality of the spot colors is generated by the fact that orange, for example, already exists as a separate color and does not have to be mixed from magenta and yellow before the spot color simulation.
Of course, it must be said that there are limits, especially in the area of metallic or fluorescent colours; these colours are currently not reproducible in proofing.
The spot-colour simulation of gradations is also critical
In most proofing systems, only the 100% values of a Pantone or HKS color are underlaid. If, for example, a font logo with 100% color application of a Pantone color is to be simulated, this is precise and is well represented in most proofing systems.
However, it becomes more difficult if the logo contains not only 100% areas but also a 30% Pantone colour area, since this is not defined in the proofing system, but is simulated by the proofing system. In some cases, considerable deviations from e.g. HKS colour fans can be observed.
It becomes even more difficult if, for example, a grayscale TIFF lies on a 100% HKS area and overprints. For the graphic professional it is immediately comprehensible that the HKS surface simply has to become correspondingly darker at this point due to an overprinting 30% black. However, the proofing software must recognize this effect correctly, calculate it correctly and then simulate it correctly with the 11 colors available from the proof printer. It is easy to understand that countless errors can occur. And the supreme discipline: 7-colour Pantone files with lots of overlaying and overprinting Pantone colours or HKS colours with overprinting CMYK elements can at best be calculated even by the most modern proofing systems, but can by no means be colour-accurately simulated.
The bad news is that a proof with spot colors is therefore never as color-binding according to the current state of the art and varies more depending on the proofing system.
But the good news is that spot colors, especially solid colors, can now be simulated well by modern proofing systems. A modern proofing system therefore also offers the possibility of getting a realistic impression of spot color prints at a fraction of the cost of a test print on a offset press.
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.
Every print shop in Germany adheres to a predefined standard, the process standard offset printing. This standard defines target and tolerance values for printed products. In order to prove that your proof delivered to the print shop meets these standards or is within the tolerances, the media wedge is measured and the values analysed in case of doubt – i.e. in case of a streak. If these measured values are correct, the print shop is obliged to adhere to and achieve these values.
Practice generally shows the following: If you want to have a 4-page image brochure proofed and printed, it is usually sufficient to have a single media wedge printed under the 4 pages. If the media wedge is also provided with a test report, the colour accuracy for the print shop is directly confirmed as a guideline.
However, if you want to be on the safe side, have a separate media wedge (including test report) printed under each of the 4 pages of your brochure.
To ensure secure data exchange between customers and proofing service providers, fonts must be embedded, converted into paths or rasterized. This ensures that it is and remains exactly the same font and exactly the same style.
How do I do that?
A proof is only as good as the light under which it is viewed. Just going to the window or switching on the light at dusk is useless: between December and July, between 8 am and 8 pm, between cloudy and sunny days there is a huge difference in the lighting, which makes any colour evaluation impossible. And if you switch on the light, you normally switch on a bulb with 2700 Kelvin – or even worse: an energy-saving neon bulb that somehow shines in any spectra… a disaster!
The reasons for metamerism effects (in short: that two colors look identical under one light, but completely different under another) lie in the different printing technologies. Colors that look the same under a light bulb can suddenly look very different under a neon tube.
In recent years, ink-based digital proofs have established themselves in the proofing sector. Because it is printed in ink, specially coated paper must be used, which is not in any way similar to the subsequent production run. Anyone who has ever tried to print on glossy coated paper with an inkjet printer knows: the ink never lasts! Metamerism is therefore always involved when a proof is to be compared with offset printing.
The light under which proof and production run are viewed is particularly important.
ISO 3664 regulates standardized light, which is important for viewing proofs and prints. D50 is no longer D50: The International Lighting Commission CIE has revised ISO 3664 in recent years and adapted it to today’s circumstances. If UV components used to be strictly prohibited, they are now part of the standard. In the past, the focus was on consistency between slide and print, while today monitor, digital proof and offset printing are important. Therefore, proofs must always be viewed under D50 Standardized Light, so that they are really “colour-binding” in their perception.
If you want to check metamerism effects, we recommend the UGRA colour temperature indicator. With these strips, metamerism effects can be checked very quickly and clearly.
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.
Proofing service providers are often asked the question: “I have to have a proof done, but I don’t know for which profile. Can I also have a proof made without a profile?”
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.
Requests such as the proof of a printed tin can often reach us. Why can’t such a printed can be “proofed”?
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:
“Paper type 1 and 2, glossy and matt coated paper, dot gain curves A (CMY) and B (K) from ISO 12647-2:2004” (Source: farbproofs.de)
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.
Customers are often unsettled when they hold a proof in their hands. “The proof of the picture is much darker than the picture on my monitor. Why is that so? And what do I do now?”
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.
Nowadays, two different processes are used in web offset printing: heatset and coldset.
The coldset process is mostly used to print newspapers and paperbacks, with the printing ink drying purely by absorption.
In the heatset process, the paper is passed through a large dryer and a chill roll unit after the last printing unit. The length of the printing press is almost doubled by these two units. To ensure that the ink dries optimally, special heat-drying inks are used here.
“We print 135gr/sqm on a Berberich Allegro. Can you make us a proof on this paper? Can you proof on our final production paper?”
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…)
Proof.de has introduced new packaging for proofs up to DIN A4+ and from A3.
The new A4+ packaging are made of high quality Chromosulfatcardboard with 450gr/m² weight and provided with a pull tab. They can be fitted on the front either with an adress label and postage stamp or for express shipments with a DHL Express label, as shown in the picture below. For shipping abroad we use to send via world letter large with registered mail, which is now directly printed as an adress label with stamp.
The new cardboard shipping sleeves are slightly slimmer than before and also provided with a comfortable pull-tab. The new address labels are easy to recognize as of Proof.de. For the different formats between Proof DIN A3 and DIN A0 + they are available in various lengths and are each used appropriately according Proof size. They are used with DHL shipping labels for the standard shipping and express delivery.
Moire is always created when screens overlap. Typical examples:
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?
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. (more…)
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.
This is the first incomplete list. You know of other good reasons? We look forward to any comments and would be happy to add further points.
In the early days of color spaces Apple and e.g. Photoshop up to version 5.5 set the monitor color space as working color space by default. But it soon became clear that a design office would be working with 10 Macs in 10 different color spaces. A neutral concept was needed.
There are many RGB Colour Spaces around. In the area of print media there are currently primarily three different variants: sRGB, AdobeRGB(1998) and eciRGB_V2.
The sRGB color space is widely used in digital cameras and is the industry leader in the consumer segment. Problem for printing: sRGB is a relatively small color space, and does not cover the color possibilities of modern offset printing systems and digital printers. Since offset printing profiles such as ISOCoated_v2 have a much larger color space, it makes little sense to perform retouching in sRGB.
From our point of view eciRGB_V2, a further development of eciRGB, is optimal. This color space has been specially created for use in the printing sector and offers some strengths:
The AdobeRGB 1998 color space, which has been widely used by Adobe since Photoshop 5.5 and today in all parts of the Adobe product range, is also well suited for the printing sector, but works with a gamma of 2.2 and is designed for degrees of whiteness from D50 to D65. All common print color spaces can also be well mapped in AdobeRGB 1998. You can find Adobe documentation on this color space here.
A proof is prepared according to the currently valid ISO standard 12647-7 and is legally binding with a UGRA-Fogra media wedge and measurement report.
How does this check work?
If you need a proof with UGRA/Fogra Media Wedge CMYK V3.0, there are two ways to add the test report to your data.
What is the advantage of automated creation and checking of the media wedge directly in the proofing device?
Further information on the test report, the media wedge and on the work and responsibility of UGRA/Fogra can be found at www.ugra.ch and www.fogra.org.
We produce proofs for classic white uncoated papers on a daily basis, but the question often arises as to which proof standard could be used for printing on recycled paper.
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.