Rgb vs cmyk: all the notions you should know

This is a special tutorial that departs a little from the topic on office automation and peripherals to which we have accustomed you here. It is specifically aimed at content creators who use digital format for most of their work and then find that they have to transfer it from RGB to CMYK and are in the situation of how to carry it out in such a way that the color is what it is. least disparate possible. We will also cover topics such as printing methods or the best way to optimize files. Having said all that, we enter the deadly and endless duel of RGB vs CMYK color. Let's start!

Index of contents

What is the color

Color is light. Specifically, the impression produced on the retina by light rays reflected and absorbed by a body according to the wavelength of said rays. The human eye perceives colors in what we call the "visible light spectrum, " which ranges from wavelengths of 400 to 750 nanometers.

In this article we must differentiate between what we are going to call “light color” and “physical color”. There are three standard models that the industry generally uses to manage the production of both monitors and stamping and printing: RGB, CMYK and PMS.

• The light color is governed by the RGB spectrum and is generated from the mixture of red, green and blue. RGB is the color parameter that our screens work with. The physical color is what we know as the resulting mixture of pigments to generate the other colors. Traditionally defined as CMYK (cyan, magenta, yellow and black) for standard printing but we must also take into account the Pantone PMS (Pantone Matching System) model is a standardized catalog of addition mixtures resulting from CMYK that give rise to a color cigar that is registered with a serial number. Their "measurements" are given by their proportion of each color and guarantee to always be the same. Big brands like CocaCola, Ferrari or T-mobile have their own pantone with CopyRight.

RGB color

The RGB color space has been attempted since its inception to standardize as reliably as possible the volume of color found in the visible light spectrum. Currently we can find three models used in RGB.

sRGB

Standard RGB, is the original model and closest to the real color (based on cyan, magenta, yellow and black) or 2200 Matt Paper . It is also the standard model for the internet and the vast majority of electronic devices since its color margin is the smallest in the catalog.

Adobe rgb

Next in size. Created in 1998, this improved model expands the sRGB color catalog by up to 50%. By displaying a larger palette it is an ideal color space for editing, illustration and design work. In general, it works on both images that will be used for web format and for printing, so it is later transferred to CMYK with a better color quality.

ProPhoto RGB

ProPhoto RGB was introduced by Kodak in 2011 and is the most recent on the list. Of all of them it is the model with the widest register, standing out for including more colors than the human eye can perceive. This is because it is the closest to the more than 16 million existing RGB light colors. This makes the images and video created with this spectrum very rich but difficult for editors to work with since at least 13% of this spectrum are "imaginary colors" for us since we cannot discern their tones.

Technical issues

Once we understand that there is no single standard in RGB, we find that in our digital workspace there are various aspects to consider when moving in an LED environment. Knowing what types of screen benefit us for our work or how to calibrate the color of our monitor are some of the most basic principles. This is why designers and illustrators are so concerned with choosing their screens in an attempt not to distort the colors of the actual finish versus what they see on their monitors.

Color according to the monitor

Knowing the type of LCD panels that our monitor uses is very important when understanding how true our perception of real color is. Currently there are three families, each with its own characteristics:

Orientative table of types of lcd panels

Without a doubt, the IPS models are the most recommended for video editing, illustration, graphic design, web design and photo retouching. This is due not only to the quality of their panels but to the type of contrast they offer.

RGB monitors are often specified in IPS monitors: sRGB and Adobe RGB are the most common.

Calibrate the screen

Once we control the issue of types of LED panels and RGB environments comes the aspect of calibrating the color and contrast of the screen. We can have an IPS LED monitor with Adobe RGB but its contrast or brightness may not be ideal for working and may alter the way we perceive colors.

You will see, in contrast, each monitor is the son of his father or mother. By this we mean that there is no standard and each company is governed by the parameters that it considers best according to market studies. As traditionally said, "virtue is in the middle ground . " Having just the brightness and contrast at 50% is generally an ideal method to follow, but here several questions and / or problems may arise.

As a general rule, the contrast parameter of monitors is one more technical specification that companies usually provide. A 1000: 1 contrast ratio is ideal.

Knowing these data, there are various actions that we can carry out. Traditionally, the most effective way to check the brightness and contrast parameters of our monitor is the DDC or Display Data Channel . It consists of a list of digital communication protocols between the monitor and the graphics card to which it is connected. Most monitors incorporate it and it is an “analog” way of calibrating using buttons on its lower margin or one of its sides.

Through websites

There are specialized websites to help regulate these parameters. We recommend some of our favorites:

• PhotoFriday: it is a portal specially aimed at photographers, both amateurs and professionals. In it we find a very concise and effective brightness and contrast calibration section with which to regulate any monitor. lagom: it is a somewhat old but very complete portal that helps to calibrate and check many of the parameters of our computer in addition to the traditional brightness and contrast: gamma, gradient, hardness and response time, among others. Online Monitor Test: also a somewhat old portal that has the advantage of allowing the color calibration test on two monitors simultaneously, which delights those who work in a multi-screen environment and want to make sure they have the same shades in all of them.

By Operating System

Apart from these websites and far from what many may despise at first, the calibration system offered by both Windows and Mac Os is very suitable for a first contact and to do it in a basic way.

• In the case of Windows we will have to write "Screen color calibration" in the search panel so that the option appears and from there follow the steps of the tutorial. It is very simple. On Mac OS the Monitor Calibration Wizard is found in System Preferences. Likewise, we only have to follow the indicated steps.

To carry out this calibration from the Operating System we recommend that you start with the screen from the factory mode since, if it is already customized, alterations may occur.

Through Software

Finally and as an addition to the web portals and system configurations we recommend a software:

• Calibrize: is a program of just over 1Mb in weight that helps calibrate our monitor in three easy steps. If we change screens often or we have several to calibrate separately it can be a very good option.

With colorimeter

This already requires the use of a dedicated device that we may well have from before or buy. It is the most impartial and reliable method since it is governed purely by numbers and percentages, but it is also the most expensive option. We have added it because it exists, but unless you are professionals in the field with everything mentioned above, you can have more than enough to calibrate your monitor using your own eyes as a calibration system.

Calibrated with SpyderX Pro colorimeter

That said, the colorimeter is a terminal dedicated to identifying color and its shades, which is in fact also used for quality control of "real" products (pigmented, dyed or printed). The highest-end monitors (always IPS) include their own Look Up Table (LUP for friends) that can be connected to the colorimeter so that it can carry out the calibration taking them as a reference.

File format

Having explained all the possible technicalities about RGB, monitors and calibration, we come to the fun part that content creators usually deal with: creating and saving files for offset or digital printing. Up to this point it does not matter in which format, program or application we have created our design, but it does matter the type of file and the workspace with which it is saved. We explain it to you in a simple way.

File format is the term by which we refer to the way in which the information in a document that we save on our computer is compressed, encoded and organized. In the field of design and illustration the most used are:

PNG: Portable Network Graphics

The king of the internet, memes and web design. PNG is the digital format par excellence given its light weight and high image quality. Another of its virtues is that, unlike JPEG, it has the ability to be transparent, which gives it many points in the digital environment, but none in printing, since the originally transparent spaces are left blank. The color profile of a PNG file is always RGB.

JPEG:

It is indicated for medium quality web images. It is an extremely widespread format. Its base color profile is RGB although it can be converted to CMYK to see how the same image changes to its printed color version. We show you an example:

As you can see, giving a JPG or JPEG a CMYK format "kills" the color information to a great extent. If this is the format you decide to take to print, it is recommended to present the file in unprocessed RGB since it would go through two processes: the one of the previous conversion that you do in the native program and the one that may also occur in the printing press. It is also not a format that we recommend you take to print except as a last resort precisely for this type of problem with the final result.

PDF: Portable Document Format

The quintessential printing document. However, it is not enough to take our file and save it as such, there are a couple of things that you should know to obtain the best possible printed quality:

Here we have the question of the PDF format. Although high quality printing is a safe bet in terms of compression, in a printing or copy shop it is appropriate to carry PDF / X of any of the categories that our editing program has. We explain in a simple way the main differences of each of them:

• PDF / X-1a: It is purely CMYK with an ICC ISO 15930-1: 2001 profile . PDF / X-3: Supports RGB, CMYK, and CIELAB color spaces with various ISO 15930-3: 2002 profiles . PDF / X-4: Add gray management and option to content with transparency. It is ISO 15930-7: 2008. and has been revised as ISO 15930-7: 2010. PDF / X-5: implement slight improvements, we can find three variants. It is originally ISO 15930-3: 2008. All its revised versions instead are ISO-15930-8: 2010.

1. PDF / X-5g: allows the use of external graphic content. PDF / X-5pg: Adds the possibility of an external ICC profile to the document as a color reference. PDF / X-5n - Allows the external ICC profile to use color spaces other than grayscale, RGB, and CMYK.

In view of all this, it is best to always export to PDF / X-1a or PDF / X-3 to ensure maximum compatibility. Sometimes it may happen that the latest versions of Acrobat are not available in printing presses and thus we heal ourselves in health.

Editable files

So far we have only seen non-editable files that feature raster or vector images. However occasionally and depending on the type of work (especially we are talking about for graphic designers) it is convenient to bring to the press an editable file where the properties of layers, effects and transparencies are natively preserved. The most used formats are:

• EPS: Encapsulated PostScript. PSD: Power Spectral Density AI: Adobe Illustrator

In all cases, the content can be presented in vector (what we see is scaled mathematically) or rasterized (the size is based on pixels). This is an aspect that totally depends on our working system and tools that we use, so we will not cover it in this article.

ICC profiles

Well, we already know about RGB color, monitors, settings and file formats. We come to the last aspect that we should know and they are nothing more nor less than ICC profiles. You will have seen that we have mentioned them just in the previous section of the PDF formats and now you are going to see their importance.

An ICC profile is a database that following the standards established by the International Color Consortium (ICC) defines the color space and how it is read or emitted by each device. Basically it's the rule that normalizes color attributes. Since each company and manufacturer can establish their own profiles for their products, the reference to create all ICC profiles is part of CIELAB (100% light color spectrum). It is something like the "master profile" that encompasses all the others. With that said, let's get to what matters. What profiles should we use? Well, the most used internationally are:

ICC in RGB:

• Adobe RGB 1998sRGB IEC647-2: 2004

ICC for CMYK:

• Coated FOGRA27, ISO 12647-2: 2004Coated FOGRA39, ISO 12647-2: 2004

CMYK color

The lord and master of the industry when sales do not depend on the screen, is that RGB vs CMYK has nothing to do here. The sum of cyan, yellow, and magenta (in addition to black) set all other colors in a result called process color. However, there is no one way to do it. Let's take a look.

Digital printing

It is the process of direct printing of a digital file to paper or other materials. This is the method that we will most commonly use since at present we can not only obtain a very good quality of finish, but in general it will offer us a good price. There are two variants.

Injection (liquid ink)

Also called a continuous ink printer. Do you remember when you used to print a full color photo at home back in the 90s that seemed to take half a life? Yes, you had one of these. And so do we. Liquid ink color inkjet printing is famous for its slowness and the ability to peel off when it was still fresh. That was living dangerously.

We have added it to the list for two reasons: the nostalgia factor and the recommendation never to use it again. That ship has already sailed, it took all its cartridges with it and the laser printing is here to stay.

Toner (dry ink)

Toner what we know as laser printing. Its printing speed is much higher than that of liquid ink and although when it appeared its print quality was nothing out of the ordinary, this has improved and the reality today is that practically everything is printed with lasers. Now it is the coolest of the show because everything does it faster and better than the inkjet printer.

Offset printing

It is a printing procedure that consists of an embossed aluminum plate that prints with ink on a rubber roller that stamps the color on the paper as it passes. As in the digital model we can find two modalities.

Four Colors (OFFSET)

Each plate has cyan, magenta, yellow and black applied respectively. These overlap creating the process that thanks to its density and color combination creates the illusion of all the others.

Spot Color (OFFSET)

Colors previously mixed are applied to the plate. This would be the case of the Pantone print since each color is already the product of a previous mixture with an established formula. The same occurs with metallic or fluorescent colors that are not obtainable through CMYK process.

With which to print

We understand that it is a lot of information at once, so we add this section to clarify what type of printing is best indicated according to what job:

Digital printing

Always with laser. It can be made in many materials and as a general rule it will be cheap. Worth it for low volume production (less than 100 or 300 copies) in color or black and white.

Offset process color

Great productions. Magazines, books, newspapers, advertising posters. There must be a large volume of work for the cost of the plates to be profitable.

Spot Color Offset

A single color business card, monochrome logos or brochures or two or three colors maximum. They must also have a good amount of production but the direct color adds that touch of distinction and consistency that CMYK lacks.

Conclusions about RGB vs CMYK

It is well known that the RGB color spectrum is significantly wider than CMYK. The limits of the second are governed by the demands of physical color while the first depends exclusively on light. It is true that in our monitors we can see the same illustration with a wealth that it would lose once printed, but this is a reality that we deal with daily given that although many of us carry out editing work in a digital environment, our final work may be made for real world and not just being seen on a screen.

Is RGB vs CMYK better? Not at all. Both are made for different environments and be the most efficient color mode in it. A good knowledge of the basic principles that imply the use of each one of them will guarantee us to get rid of more than a headache in the future and a quality job and without surprises when it comes to printing.

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We hope this tutorial guide has been helpful to newbies and a good summary for veterans. If you have any questions, remember that you can always find us in the comments. A big greeting!