Hello, this is Matsumura, the representative of “PHOTOPRI” who works as a photographer and printer!

This time, I will explain the difference between "RGB printing" and "CMYK printing".

Both are phrases that you hear when you are doing cameras or dealing with photography, but what is the difference?

"What is the difference between RGB printing and CMYK printing?"

“Where should I print?”

"When do you need to use them properly?"

In order to resolve this issue , this article will explain why RGB printing is recommended and how it differs from CMYK printing.

At the end, there is also useful information that can be used when doing "RGB printing", so please read to the end!

What is RGB printing?

RGB printing is a print setting that allows you to print data created in the RGB color mode.

Unlike CMYK printing, which is used for general printed matter such as for office and home use, RGB printing has better color development, and it is possible to print with colors similar to those seen on the screen of a PC or smartphone.

Therefore, it is possible to reduce the color difference between when editing on the screen and when printing.

It can be said that it is a print setting that makes it easy to achieve professional expressions such as “I want to do a little more”.

What are RGB and CMYK in the first place?

What is RGB?

RGB is the so-called "three primary colors of light" .

It reminds me of science class...lol

The light that humans can perceive in nature is made up of three types of light: red, green, and blue .

Taking the initials of these three light initials (Red, Green, Blue), it is called RGB.

The colors we see are created by mixing the three lights of RGB. For example, displays such as TVs, PCs, and tablets are all colored by the ratio of the three types of light.

The human eye can only perceive these three colors of light.

The LCD screen expresses colors with three colors like this.

Representing colors by combining three lights of RGB is called "additive color mixture" .

This means that when all colors are 0, the result is black, and when all colors are mixed, white is created .

The reason why the display turns black when the power is turned off is related to additive color mixing!

What is CMYK?

CMYK is the addition of black to the so-called "three primary colors of colorants" .

The colors of all paintings and printed materials are made up of a combination of three colors, "Cian", "Magenta" and "Yellow" + "Black/Key Plate".

Taking these acronyms, we call them CMYK printing.

CMYK colors are created using subtractive color mixing .

This means that if all colors are 0, you get white, and if you mix all colors you get black.

Increasing the amount of color makes it closer to black, and decreasing the amount of color makes it darker.

In printed matter, the color is determined by the ratio of the four CMYK inks. You can specify 0% to 100% for each color, and you can also specify numbers after the decimal point, so the number of colors that can be expressed is considered to be more than RGB in terms of calculation.

However, in actual printing, it is not possible to express such fine color differences, so it can be said that there are fewer colors that can be expressed compared to RGB.

However, with CMYK, even if exactly the same color is specified, the output color will be slightly different depending on various conditions such as the condition of the printing machine, the condition of the ink, and the paper.

Cyan has a little bit of yellow or magenta mixed in, and vice versa.

Therefore, even if you mix three colors of ink, you will not be able to make black well.

That's why you need a "black/key plate".

The "key plate" is the so-called black ink, and it is necessary to use black ink to adjust the color because it is not possible to create a beautiful black when three colors are mixed.

Why we recommend RGB printing

In the first place, the range of colors that can be reproduced is quite different between RGB and CMYK.

RGB is wide, CMYK is much narrower.

CMYK can cover only a smaller range than RGB of the colors visible to the human eye (Visual).

In terms of numbers, CMYK can only reproduce RGB colors by about 65% .

Therefore, if an image made in RGB is converted to CMYK, the colors that protrude from the color gamut will be forced into the CMYK color gamut, resulting in considerable discoloration.

However, basically, it is necessary to convert to CMYK format before submitting the data to the print shop. In particular, blues, greens, oranges, and dark purples are highly likely to deteriorate, and if they become dull, the overall impression of the data will change significantly, so be careful.

When you change from RGB to CMYK, the colors change like this. (Although the change is significant due to conversion to gif format,,)

If you convert from RGB to CMYK with Photoshop, etc., you can reduce this color change a little more, but if possible, you would like to print the data as it is in the image taken in RGB.

When should I use RGB printing and CMYK printing properly?

Basically, the RGB printing and CMYK printing settings are used according to the color mode of the data to be printed.

Most of the data captured with a single-lens reflex camera is in RGB color mode, so if you want to faithfully reproduce the captured data, choosing RGB printing will produce the output result closer to what you imagined.

Conversely, when printing data whose color mode is CMYK, CMYK printing is mostly used, and general printers and Internet print services often only print CMYK.

I think that the data is often printed after changing the color mode from RGB to CMYK.

Color mode: RGB → Print settings: RGB

Color mode: CMYK → Print settings: CMYK

If you don't match the data and print settings, you'll end up with completely different colors...!

RGB printing is recommended in order to reproduce the retouched image with colors close to those of the display.

How to change color mode using Photoshop

Here, let's use Photoshop to convert to CMYK.

Select "Mode" from "Image", and if the color is "RGB color", change it to "CMYK color".

However, unfortunately, even if you convert in this way, if you change from RGB to CMYK, there will be areas where colors cannot be reproduced and become dull .

Many printing companies recommend converting images to CMYK before retouching in order to avoid the problem of dull colors in general printing.

Use PHOTOPRI for RGB printing

Our service, "PHOTOPRI", aims at high-quality printing used by solo exhibition artists and professionals in various industries, and supports wide color gamut RGB and Adobe RGB printing.

Even if you do not convert the image to CMYK, if you print in RGB, you can print the original RGB image as it is, saving you the trouble of converting it, and you can print with colors that are not dull.

First of all, there is a free trial print, so if you want to try RGB printing but can't do it at home, please try it.

---