So what the hell is "color space". Many people ask this question and at the same time silently complain that they do not understand it and at the same time need it. So what are all these descriptions and labels - Adobe RGB, sRGB, ICC, ...? In short, these are numerical records that determine the values of individual colors, i.e. standards. Since usually all devices (monitor, printer, digital device...) show a different image, some standard is absolutely necessary.

It should also be understood that all these devices are not equally capable of displaying colors. Not to mention the multitude of different manufacturers and the confusion is even greater. Due to its technology, even the monitor has problems displaying some theoretically defined colors, let alone printers. Let's leave aside the fact that each eye has its own painter. So we need some standard that will unite this - equipment developed in a hundred different areas.

Standard

A good 15 years ago, Microsoft and HP set themselves the task of straightening things out a bit. Hand on heart - Adobe had already arranged these things, but their sinfully expensive products were mainly the domain of professional studios, where dedicated people were engaged in preparation for printing on Apple typewriters. But now everything has become more widely available (unfortunately also with a lack of knowledge). Well, anyway, a new standard was created - sRGB, which is built into every digital camera today, some better ones, especially specular reflex ones, and the slightly more extensive Adobe RGB.

Areas covered by different color spaces/records.
We can see how the space when printing in CMYK technique is limited due to the display technology.

How we hunt the green rabbit.

So how best to prepare image files? It depends, of course, what we need them for. For most needs, the sRGB color space is sufficient, which describes colors very well, only in blue-green shades it is slightly "carried" by Adobe RGB. We can use it everywhere, especially when displaying on the web, because most browsers do not understand a different model and, in the case of Adobe RGB, show us washed-out colors. Color spaces can also be set/converted in Photoshop. However, we must know that most printers only understand sRGB and for average use it is better to leave photos in this basic format. If we are going to play with the conversion to Adobe RGB in the hope that we will get more shades from the photo, we are in a bad way here. Namely, certain information basically does NOT exist and is NOT conjured by any conversion. With an inadequate conversion, we will at most "cut" the part that is rich in information. Printed photos will be pale and washed out.

So the numeric values are moved up and a simple printer doesn't understand it. There's nothing to blame him for. Namely, it behaves according to the most widespread standard - like the previously mentioned web browsers. If we have already captured or obtained the image in Adobe RGB, we simply convert it to sRGB and the printout will be beautiful again. Something else is professional printing machines and illuminators that use RIP technology. There, the file is taken over by the controllers, which we describe as ICC descriptions and are adapted to each machine individually. In that case, capturing in Adobe RGB makes sense, because we will only convert this into an ICC description, and because we need as few losses as possible - so let's use a color space that will offer the description as wide a selection of shades as possible. This also applies when choosing colors for say integrated graphic image. It is wise to choose such a set of colors that the screen and printed display will be as identical and realistic as possible.

CMYK color space

It's not actually a color space, but a hue simulation by mixing 4 colors. We use it in offset to the press and has a much smaller color range than the above-mentioned RGB. In particular, more vibrant colors such as bright green and bright orange give him a problem. Here, too, for an optimal result, you should in principle know the machine on which the printed matter will be produced, because in this case we develop the image into an ICC model of this particular machine. Thus, we would make maximum use of its possibilities of correct and desired display on paper. Of course, under the conditions that strict rules are used in lighting and printing and the whole process is controlled.

Another short tip - we must always store the image material in RGB files, only when using it for printing, then we make a CMYK copy. When converting to a smaller color space, certain information is lost forever and there is no going back. Well, we caught a rabbit.

There will be more on this topic in one of the next posts, where I will deal with the human perception of color and how colors are created.