Is a proof possible on special paper such as publication paper?

“We print 135gr/sqm on a Berberich Allegro. Can you make us a proof on this paper? Can you proof on our final publication paper?”

Our telephone support often asks for a proof on publication 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 publication 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.

Stamp once on a coated printing paper. You can easily wipe off the stamping ink even after many days. The situation is similar with inkjet inks. And even colour laser printers are no solution. The toner applied to the paper in these systems and then liquefied by heat to bond with the paper cannot penetrate the closed coated surfaces. This means that the print is not fused and the toner can be wiped off the surface directly after printing.

Modern digital printing systems such as the iGen from Xerox are also capable of neatly mapping color spaces such as ISOCoatedV2. Some of these systems are also able to print offset papers properly, although here too special papers optimized for digital printing are used. However, despite major improvements in recent years, these digital printing systems are still not capable of reproducing the small color deviations required for a true color-accurate proof, a “contract proof in accordance with ISO 12647-7”. Even after a complete recalibration and re-profiling on the paper used, these systems only achieve “Validation Print” quality according to ISO 12647-8.

“Validation Prints” are not “contract proofs”, they are not color-binding and not legally binding, since the permissible color deviations of Validation Prints may be significantly higher than those of real proofs. The result would therefore only be a “print”, which is not binding for a print shop as a result, not “color-binding” but only “colored goods”. And it is precisely this commitment that must be achieved with a proof. In addition, the color stability of these systems is predominantly so critical that even with a new profiling in the morning in the afternoon, even the lax validation print tolerances can no longer be achieved and the system again has to be recalibrated and profiled.

The only solution: the classic proof. If it wasn’t for the cost.

Here, real offset printing with real colours produces the real print later in an edition of one piece. Since the proof is printed in real offset printing, production paper can also be used here without any problems. The downside? The price. Depending on the format, a proof on circulation paper costs several hundred euros. Since press proofs are still predominantly film-based printed today, but the real printing is usually via computer-to-plate printing plates, there is no 100% precision of the press proof for the production print today either. CTP is also available from proofing companies, but at an even higher cost. A little postcard, a slim fanfold? This is not economically viable in proof printing.

So don’t use circulation paper for shorter print runs. Especially with ISOCoatedV2, a classic proof offers you true color accuracy and stability at very low costs. Just lay the cover paper next to it. We are sure that this is the best way for you to imagine what the subsequent printing will look like, in the “most colour-accurate” and also at the best price. And in comparison to Validation Print digital printing, it is legally binding and binding in colour.

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Reproduction of anaglyph images and line drawings

Already a few weeks ago we received an unusual request: The musician and aspiring art student Tobias Weh from Osnabrück experimented with line drawings based on anaglyphs and achieved very good results on the monitor. He created superimposed line drawings, which then delivered a different image when viewed through the left eye than when viewed through the right eye. The question was whether this could be reproduced better with the high color range of a proofing system than with a simple domestic inkjet printer.

Since such questions are of course very interesting at first sight, we were quickly prepared to support Mr Weh in his work. To get closer to the matter, we use an i1 Pro 2 and BabelColor Color Translator & Analyzer to measure the spectra for the two films, which are transmitted through standard anaglyph glasses.

Anaglyphenbrille - Durchgelassenes Spektrum der beiden FolienActually a very satisfactory result. By choosing two colours as printing in the spectral ranges of 450 to 500 nanometres for blue and 650 to 700 nanometres for red, it should actually be possible to achieve quite a good result. The first idea was to use the LAB values measured by BabelColor to create the respective red and cyan color in the print. Unfortunately, however, this does not really work; the measured printed colours could unfortunately not be spectrally matched at all with the desired colour.

Anaglyphen-Druck_der_gemessenen_LAB_WerteSo we continued to experiment and found two colors that should actually harmonize very well spectrally with the transmitted spectra of the glasses.

Anaglyphen-Druck: Gewählte Farben für TestBut even here the result of the visual inspection was devastating. A strong ghosting in both colours was permanently predominant, a clear colour separation was not possible. Also a look through the foils of the anaglyph glasses on different Pantone fans in order to find by a visual color selection a color as suitable as possible did not bring any result. In red the glasses worked quite well, in the cyan area none of the Pantone colour fields disappeared even approximately in front of the human eye.

Blick durch die blaue Anaglyphenbrille auf rote Pantone Farben Blick durch die rote Anaglyphenbrille auf rote Pantone Farben

Amazing was also the effect that the Pantone neon colors like the Pantone 811 C delivered visibly brighter color results for the eye and even for a camera than the pure white paper. The two pictures above are snapshots of an iPhone camera through the two filter films of the anaglyph glasses. The red area clearly shows that some Pantone colours disappear completely through the film, while all Pantone colour strips are completely visible in blue.

As the only pragmatic solution we finally developed a compromise: We brightened up the colours red and cyan to prevent ghosting and coloured the background of the paper slightly light grey instead of white. This minimized ghosting, especially in the cyan area, so that the desired visual effect of the anaglyph image was achieved.

Even with intensive research on the Internet, we were unable to produce any other or better result. In several articles by a Frenchman Eric Dubois, the dilemma is quite well outlined, but his results did not really help us with our problem of line representations.

Some important links about anaglyph printing that we stumbled across during our research:

http://www.site.uottawa.ca/~edubois/anaglyph/

https://forums.adobe.com/thread/377398

http://en.wikipedia.org/wiki/Anaglyph_3D

Tobias Weh fragte auch im Typografie-Forum nach Erfahrungswerten an.

http://www.typografie.info/3/topic/31883-anaglyphe-bilder-drucken-rot-grün-3d/

But here, too, there was no further evidence of a better approach.

Conclusion: The anaglyph area seems to work very well on screen. This is supported by a large number of Kindle eBook publications, which Amazon sells for little money. This is where the anaglyph effect really works, a high quality monitor is not necessary. However, this high-quality result cannot be reproduced in printing.

The hardcopy books currently available on the market with anaglyph images are mainly filled with historical stereographic images, which are based on a two-colour and thus grey background. This probably has two advantages: The two-tone grey minimizes ghosting, and in historical images our human tolerance threshold is simply higher than in modern photographs or line drawings.

If you have an idea how to produce a ghosting-free anaglyph image with modern printing systems, please contact us. We look forward to receiving further input and feedback on our deliberations.

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Easy conversion of Pantone – HKS – CMYK – RGB with Adobe Photoshop

Farbbücher Auswahl in Adobe Photoshop CC: HKS, Pantone, CMYK und vieles mehr

More often the question arises as to what kind of Pantone colour corresponds to the HKS 43 K. Or what CMYK value? And what kind of web color in RGB?

If you own Adobe Photoshop, you can do these conversions directly there. In Photoshop CC all well-known color books are stored with values.

Let’s assume we are looking for the Pantone equivalent and the matching CMYK color of HKS 43 K.

1: Open the color palette in Adobe Photoshop and select HKS K as the book and then the color HKS 43 K. All well-known colour books are directly stored in Photoshop.

Farbauswahl von HKS 43 K im Buch HKS K in Adobe Photoshop CCThe color corresponds to a Lab value of 26/29/-79 and a CMYK value is already stored here. Simply select the book HKS K Process: Continue reading

Layout in RGB, print in CMYK. Problems?

Especially in larger companies today the layout in RGB is the rule rather than the exception. The advantages are obvious:

  • The layout takes place in a large, almost media-neutral color space
  • All Photoshop filters are available without restrictions
  • The process of color space conversion to CMYK is shifted to the production process as late as possible

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:
Continue reading

The proof is much darker than the image on my monitor. Why?

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:

  • The monitor is not calibrated
    Only calibrated monitors can accurately display color. When I buy a cheap monitor and connect it to my computer, I definitely can’t see any real color. As a rule of thumb, only a hardware-calibrated monitor has a chance for correct color.
  • The monitor is calibrated, but the colors look different
    A monitor below 1,000 Euro cannot usually be calibrated to good color representation for the standard color space ISOCoated V2, because it has a too small color gamut. Only real proof monitors are also designed and suitable for the display of proofable colors.
  • The proof is not viewed under D50 standard light
    Especially in winter the lighting conditions are often poor. And incandescent lamps, energy-saving lamps and conventional neon tubes only provide very poor colour reproduction. Without a D50 light source, a proof cannot be evaluated.
  • The color settings in the software are wrong
    Often the image editing software like Photoshop is simply installed and used without adjustments. The selected color profiles often do not correspond to the profiles used for proofing. Apple-Shift-K for Macintosh and Control-Shift-K for Windows show you your profile settings in Photoshop.

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.

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White lines appearing in print PDFs in Adobe Acrobat

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.

Here you can simply deselect the option "Smooth vector graphics"

Screenshot from the Preferences of the Preview in Adobe Acrobat

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Why monitor and paper don’t get along when it comes to color.

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 color 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:

Translated with www.DeepL.com/Translator

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 color 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 color red.

One colour, two completely different ways of production. And this is exactly where the color 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” color your monitor can display, and “how wrong” your monitor can display color. 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 color. 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 color representation of the monitor and printer, it can correct and adjust the representation so that both correspond to the same color. Of course, this only works if the color 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 color-accurate representation is a so-called “soft proof”, the color-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 color simulation. And since the image processing technology, color 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.

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What’s a proof for? The most important reasons for proofing!

  1. A proof is reassuring:
    The proof shows the colour result of the subsequent printing.
    The customer knows exactly the later result from the proof and is reassured.
    The printer knows that the customer knows the proof and is also reassured.
  2. A proof is fast:
    Ordered today, delivered tomorrow: Modern proofing service providers work quickly and produce hardly any loss of time in the design and printing process
  3. A proof is precise:
    All professional service providers nowadays work with proof printers that are recalibrated at short intervals. A media wedge with test report also provides clear metrological proof that the proof is correct and within the limits of the standard deviations.
  4. A proof is cheap:
    In the past, repro studios often charged almost 30 euros for an A4 proof. Nowadays, it only costs a fraction. Proofing costs are of little importance in the production process.
  5. A proof also shows the colors that the monitor does not show:
    In most agencies, hardware-calibrated proof monitors are in short supply. And TFTs or old tubes show colors, but unfortunately some. A proof also depicts colors that standard monitors cannot display, but which can be printed.
  6. A proof simulates newspaper as well as coated paper.
    If the same advertisement is to appear in the glossy brochure for the trade fair stand, in the trade fair news and in the special supplement in the local daily newspaper for the trade fair, then the three different colour results can be excellently simulated and presented in proofs in advance. And who knows: Perhaps the customer will then have the house brochure printed on picture printing instead of on uncoated paper due to the proof, or will choose a different motif for the newspaper ad. The proof shows it.
  7. A proof can do CMYK and more!
    Modern proofing systems can reproduce up to 98% of all Pantone colours and HKS colours in the proof.  This means that not only four-color, but also five, six and multicolor files can be proofed. Today, proofing is often done twice: once in CMYK plus corporate color in Pantone and once in CMYK and corporate color in CMYK. The client and agency can then decide whether the colour result is worth the extra charge for the fifth colour in the print.
  8. A proof is made of paper.
    Just like the product he’s simulating. A proof can be placed next to the print and compared under Normal. And to check it out, you can carry both to daylight, look at them in the candlelight and much more. A soft proof cannot do all this.

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.

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Which RGB working colour space is suitable for colour-consistent work?

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:

  • It covers the colors of all modern printing color spaces (offset, gravure, web offset, newspaper), but is not much larger and therefore does not give away any resolution.
  • Equal shades of red, green and blue result in neutral shades of grey
  • Between 0/0/0 and 50/50/50 there is roughly the same distance as between 50/50/50 and 100/100/100.
  • The white is 5000 Kelvin and the gamma is 1.8 Kelvin.

The eciRGB_v2 color space can be downloaded free of charge from the pages of the European Color Initiative (ECI).

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.

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Embed profiles for proofing? Yes or No?

The question often arises whether color profiles should be embedded in the PDF files for proofing.

To answer the question, you have to get some answers: The proof should simulate the subsequent offset printing. For offset printing, with few exceptions, the imagesetters have been configured so that a 70% black in the file is displayed as 70% black on the printing plate, no matter what profile was specified in the file. It didn’t matter whether it was coated paper or uncoated paper: 70% in the file corresponded to 70% on the plate, the choice of the paper printed on resulted in the colour representation.

The proof has also adapted to this: Most proofing service providers ignore embedded profiles, as long as the data is in CMYK and do the same as their print colleagues. Even with grayscale, the profiles are usually ignored and the grayscale is simply assigned to the CMYK black channel. Thus all CMYK and grayscale data are simply interpreted as if they had been created in the output color space. If “ISOCoated V2” is proofed, all images are treated as such, and if “PSOUncoated” is proofed, then the CMYK images are created in this color space.

This is excellent for the majority of files to be proofed. Only RGB colors contained in the data are problematic.
Since the RGB color space is considerably larger than most CMYK color spaces, it must be clear from which color space to convert to CMYK according to which criteria. Most proofing service providers specify a color space from which they convert by default if no RGB color space is defined. This can lead to difficulties: For example, many proof studios choose AdobeRGB as color space because it is large and optimized for offset printing; however, most images from digital cameras come from sRGB and these color spaces differ considerably. Therefore, it is important that the RGB color space and the rendering intend is embedded for a proof, otherwise the proofing software normally selects a color space for conversion to the CMYK color space to be proofed; and this color space is possibly not the one in which the data has be created.

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Verifiability of GTIN codes in proofing

Depending on the selected setting, the GTIN lines in proofs are displayed smoother or less smooth. It is clearly visible that the modules are made up of many colours and that a considerable increase in width takes place especially within the narrow black lines. Normally a narrow black GTIN bar should correspond to the width of the white space.

Depending on the selected setting, the GTIN lines in proofs are displayed smoother or less smooth. It is clearly visible that the modules are made up of many colours and that a considerable increase in width takes place especially within the narrow black lines. Normally a narrow black GTIN bar should correspond to the width of the white space.

Proofing service providers are increasingly required to be able to display “verifiable” GTIN codes, i.e. barcodes in the proof.

The background to this is that especially the big german discounters like Aldi, Lidl, Hofer & Co. want to see a packaging proof from their suppliers in advance for approval. This packaging proof is not only visually assessed according to colour, but also the legibility of the printed EAN codes is evaluated using a measuring device and must meet certain criteria: Symbol contrast, modulation, decodability, defects, blemish: all this is measured and graded.

This involves two different risks for the advertising agency or the reproduction company that processes this data: Firstly – according to our information – in most cases the proofs are not viewed under D50 standard light, but under TL84 – the light under which the packaging will also be seen in the later sales situation. This is understandable, since the sales process takes place under TL84 and not under the standard light of a printer. On the other hand, retouching under TL84 is not mandatory, since the spectral behavior of “standard” neon means that it is not possible to produce such a reproducible and “color-accurate” result as under D50. In addition, a colour matching box with D50 and TL84 is available in very few companies, which makes it possible to view the result under both light conditions in the colour retouching.

Secondly, the proofed GTIN barcodes are measured by a measuring device and checked for their mechanical legibility. Whereas a few years ago a press proof was the standard for such tests, today mostly the digital proof is used, since it is much cheaper. But until now, the manufacturers of proofing software have always only paid attention to the representation of color, but never to the verifiability of black and white lines.

Especially with Fiery proofs, but also with GMG Color, the lines of the GTIN barcodes are usually reproduced in such a way that they correspond exactly to the black value of the required profile in terms of color, but only school grades of 3 or even 4 are achieved during the examination, depending on the discipline. Most scanner cash registers could still read and process these barcodes without problems. However, ALDI Süd or Hofer with their own GTIN codes require at least a second grade in all disciplines: The proofs all fall through the test grid of the discounters. In particular, the decodability of EAN codes has probably not been of particular importance to proof manufacturers up to now.

After detailed tests, the width increases of the GTIN bars in the digital proof and the blurring of these bars seem to be the biggest problem for the verifiability of the codes. Farbproofs.de has developed a solution together with one of the testing companies for barcodes that makes it possible to print testable GTIN codes in accordance with the strict ALDI standards, which also comply with the current proofing standards. A proof is therefore sufficient for colour matching and for checking the GTIN numbers. However, the EAN must be created and edited specifically for this purpose. This still costs far less than a conventional proof, but it is not satisfactory.  Manufacturers of proofing software such as EFI and GMG Color are therefore called upon to improve the calculation of black and white line representations in writing and GTIN codes.

Until now, the focus has always been on color accuracy, but the proof increasingly demands services that were previously reserved for proofing. At costs of 5-10 EURO for a digital proof in DIN A4 format and 150-300 EURO for a proof in the same format this is more than understandable.

An article with tips for the creation of EAN / GTIN codes for graphic designers and the problems of verifiability of EAN and GTIN codes for e.g. Aldi, Hofer, Lidl and Co can be found here.

 

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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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What is the UGRA-Fogra Media Wedge 3.0 used for?

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.

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