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:
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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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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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