Open mysterious color management

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Almost all magazines, almost every print website has an introduction to color management. It looks more like a dinner that requires labor and is sitting in danger. Compared with dinner, I prefer the lively atmosphere in the cold drink room.

Summer is coming, we don't want to be like everyone else, please everyone to eat dinner, like "color management" like steak or smoked chicken, if you want to eat it, there is a lot to learn, we don't even want to figure out these dishes. How did it work? Now I just want to tell you that "color management" is actually "cute" (chocolate ice cream). You only need to take off that layer of wrapping paper and you can eat it. Is it easy?

Let's put aside some of the headaches of color management. Let's take a look at the problem we encountered: my girlfriend's photo, I want to scan it on my computer, so that she can smile at me on my monitor every day. After the work is finished, I am very disappointed. Because I got a picture on the computer that was very different from the color of my original photo by the scanner, of course it was not what I was willing to happen.

Then, I made a lot of adjustments to this picture, including color, tone, etc., finally she could see it, so I sent it to my brother by email. Soon, I got a call from my brother: Your girlfriend's face is not good. But on my monitor, my girlfriend’s photo face is still being dealt with?

I wonder if it is his monitor problem? Just tell him to use a good printer to make a look, by the way, the mother can see. As a result, my mother called and said that she was very anxious and said that my girlfriend should go to the hospital to see.

Scanner → Display → Printer, I believe you may have encountered the same problem, then where is our problem?

Color, or color

Let's eat a bit more cute. You must notice that it is brown, the color of the chocolate. Remember the color of the skin we just peeled off? It is still brown, but this color is printed on paper with ink.

As we have seen above, scanners, monitors, and printers all display colors, but the way they display colors is different from the media (we don't want to discuss LEDs or printer colors). This will directly lead to the color difference we see, and this difference exists objectively. The same problem often occurs in many places where digital colors, such as digital cameras, proofing machines, and printing presses, need to be displayed.

Color range

We imagine dividing the color into a limited number and then envisioning using a different container to hold it. All the instruments we mentioned above, including computer monitors, digital cameras, photos, printers, scanners, printers, etc., can be used. Is a container. Through many experiments by many people (what people's experiments are not the content of today's easy topic), we all found that the amount of color they accommodate is different, just like the "cute" of the cold drink house, the egg cone is loaded. Less, and if it is a plastic box, there will be a lot of ice cream.

When we want to transfer the color of a device to another device, it is very likely that we will encounter a problem like putting a big tube into a small tube. How to put it? Will there be a part of the color that will still be lost? We will put this problem first, and in a moment you will find out how the problem is solved.

Color description

When the cuteness is over, you may want to order another ice cream, Mengniu? Still De's? Well, I want to be a cow, give you a Dess. I will tell you that Mengniu is very sweet. You said that it is impossible. The last time you eat Mengniu, it is not very sweet. When you tell me, your Deshi is still okay, it is a bit light.

This is also the case with color. There are always such problems between different devices. Every manufacturer has different standards. Even if everyone wants to get the best, what is the best? This is a subjective judgment. Just like the question of whether the ice cream is sweet or light, we just said. So is there any way we can have a unified standard to evaluate color?

The International Commission on Illumination has provided us with such a standard: CIE color system (the system is not a system, there are CIELAB and CIEXYZ, etc. These are the contents of the next part, we only need to know that there is such a standard exists), this The standard is recognized by almost everyone. This is just like the Dessert and Mengniu that we just mentioned are sweeter. In fact, we only need to compare with the "cute" that we have just eaten. Is it sweeter than "cute"? The problem is solved very well.

Color management

Finally, we brought the problem to this problem that made us all headaches. In fact, even if you don't understand the theory of color at all, eating the ice cream mentioned above, you will find that what we have to do is to convert the color of any device into something like "cute", everyone has eaten it. At the same time accepting the concept, the subjective factors of color began to become objective. Of course, this standard is recognized, and "CIE" is just like our "cute", everyone understands.

The language "Mengniu is sweeter than cute" is obviously understood by everyone, so the color problem needs a similar language to describe the relationship between our different devices and the relationship between CIE. This is the "PROFILE" file that we are going to present now. How does it express its content? Let's not go into it. We just need to know that it is a language that describes the color characteristics of our equipment according to standards such as CIE.

ICC PROFILE

I hate English, but the name is like this, just like an ice cream "DQ".

As mentioned above, PROFILE is a file that describes the color of a device based on our recognized color. It is formed by language. When it comes to language, troubles arise, will there be dialects? Can a device use a PROFILE other device to recognize it? This is also an important reason why early color management could not be carried out very well.

In 1993, an international organization called ICC (International Color Consortium, initiated by the first few international electronics and computer companies) did the work of consolidating ICC's PROFILE into a standard language, with more companies joining. Today, ICC PROFILE has become a truly universal language.

Color transfer process

I want to go through the above, the whole process begins to become uncomplicated: color 1 → PROFILE1 → CIE → PROFILE2 → color 2

Did you see it? PROFILE has become a bridge. Just like what we just said, "Mengniu is sweeter than cute," he established a connection between color 1 and CIE to make the color description more objective and fair. CIE became the whole management process. "Cuteful", through his role and the PROFILE2 described in Color 2 we establish the connection between color 1 and color 2.

This means that you can create a PROFILE for one of your devices. In the same way, we can connect almost all devices.

Real core

We will return the question to the photo we mentioned in the article. Please note that this will be the only place in this article that you need to understand.

We put the photo on the computer with the scanner. This process requires color transfer. The color range of the photo and the scanner can feel (remember that the device feels, not the human eye). This is The first reason that led us to see the color change at first.

All we have to do is create an ICC PROFILE file for the scanner to describe the color characteristics of the scanner (because the color displayed on the display is not what the scanner really describes, we can't see what the color the scanner feels like, But we know that it is impossible for the scanner to feel all the colors.) This PROFILE not only includes the color characteristics of the scanner, but also the way we want to get the best color (the closest to scanning to the photo). When the scanner is unable to faithfully describe the color of the photo, we want the scanner to describe it.

When we see this photo from the monitor of the computer, in fact, the color of our photo has been transferred a second time, then we need to make a PROFILE file for our monitor, also the PROFILE also contains How do we handle such colors when the display does not correctly describe the color of the scanned photo.

By this time, we got a total of two PROFILE files for the scanner. Let's take a look at the following process to understand what we have to do: photo → scanner PROFILE → scanner → scanner PROFILE → display PROFILE → display

In this process, we ignore it. The reason for CIE is that compared to the description of CIE, PROFILE and software have already completed these processes for us.

Next we can build different PROFILE files for additional monitors, printers and even printers. This solves the problem of color transfer between devices, which also includes how colors are handled when color rendering is not possible.

In fact, it is necessary to explain the following questions:

The color is described by the device

Different devices are described differently

In order to have the same standards between devices, we introduced the CIE standard.

We let PROFILE build a bridge that describes device color and CIE.

Through our PROFILE for each device we can control the transfer of colors between devices.