The representation of color is one of the most important points for graphic designers in different disciplines. Although in this article we are not going to tell you how to perform color correction in your favorite programs, but how color is handled by your PC hardware. Both in terms of the monitor and the graphics card itself and because it differs in that regard from the amount of color we use in the real world.
Front CMYK to RGB
The acronym CMYK stands for Cyan (Cyan Blue), Magenta, Yellow (Yellow) and Black (Black) and these are the basic colors used in graphic design on paper. On the other hand, the acronym RGB stands for Red (Red), Green (Green) and Blue (Blue) and is used on the screens of various types of devices.
Thanks to these two sets of graphic colors, the rest of the colors in the range are obtained, for example you can achieve RGB colors by mixing concrete with CMYK and vice versa. Wouldn’t a universal color management system be better then? Yes, in theory that would be better, but you have to take into account that a screen emits light, while CMYK dyes and paints reflect light from the surroundings falling on them. This means that CMYK tints are subtractive, which means that their sum tends towards black, while RGB is additive and therefore their sum tends towards white.
As for the applications, those which must generate results to be printed work in the field of CMYK colors, they therefore have two display systems: an RGB to display the document on the screen as a preview of it and another CMYK that is generated when the file was sent to the printer.
The Image Buffer
When graphics hardware, whether it’s an integrated or dedicated GPU, generates a frame, it writes it to the frame buffer, which is a section of memory in VRAM. Nowadays, we use what is called double buffering, which is that while the already generated frame is sent from the screen controller to the monitor, the graphics processor generates the next frame.
To understand the frame buffer, we have to imagine a mat in which each point is a pixel that represents a color value, which is obviously an array of colored dots. Since VRAM is linear, this is not a problem, since we can represent this matrix as a huge vector, where each pixel corresponds to a position in memory and they are all found sequentially. Of course, the value of each pixel is stored in RGB format, which marks the intensity of each of the three channels.
As we have already commented, the RGB format is additive, it affects the graphics hardware when it comes to manipulating the color value of the pixels, as it uses ALUs with the ability to add and multiply when Rendering graphics to the screen in real time at high speed. While to generate the same image in CMYK, they do not require the same speed and usually do so through a conversion process, using PostScript technology, which is usually done by the processor.
Color space in RGB and CMYK
Before, we explained to you how it is possible to obtain the basic colors of RGB through combinations in CMYK and vice versa. And we are aware that some graphic designers who have read this will have pulled their hair out.
The reality is that in the RGB pixels of a screen, we can represent a greater number of colors than by using the CMYK pigments of a printer. This is why for those who work in multimedia, color management is very important, because a color that is seen on the screen may not be represented as is in RGB. In order to obtain the exact equivalences, professionals use color calibrators or Pantone cards which allow them to obtain the same color in both spaces.
It should also be clarified that the RGB values do not represent the entire color spectrum of reality, but rather this is due to limitations when designing the hardware. It is true that it would be possible to create GPUs with the ability to work with greater precision, but considerable computing power would be wasted and at the moment the RGB space that is used is already quite good.
Using CMYK would be counterproductive
Because screens use RGB and not CMYK, all applications are designed for this way of representing color and this includes the equations to manipulate the color value of each pixel. If suddenly there was a consensus to unify everything under CMYK, the consequences would not only be catastrophic in terms of programs, but when it comes to hardware, we would suddenly find that four decades of graphics advancement would crumble.
What is an important advance would be to speed up the conversion of CMYK to RGB, especially since when opening a PDF file to be able to read it, it is necessary to convert all the pixels of the image to RGB format. If you’ve ever wondered why a lightweight PDF file takes so long to open, it’s because the device’s bad processor is choking the conversion.
It is possible that in the future artificial intelligence algorithms will be used to perform conversions from CMYK to RGB and vice versa directly and at high speed, which will not only allow us to read PDFs at high speed on our computer or tablet, but also to speed up the print queue.
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