The measurement procedure boils down to selecting the most similar color from the atlas for the color being measured.

Story

Initially, color samples were used in the form of simple scales (the so-called “color scale”), but as the number of color samples increased, it became increasingly necessary to create large color atlases. Such atlases appeared in the 20th century.

Color reference classification systems

Color synthesis method

1. Standards are made by adding white and black paints (achromatic colors) in different proportions to mixtures of chromatic colors. The classification is based on the relative amounts of chromatic and achromatic light fluxes when they are additively mixed. See additive color synthesis.
2. Atlas samples are made by mixing paints using the principle of subtractive color synthesis. The best atlases of this type indicate not only the ratio of paints for each sample, but also publish the recipe of paints and the method of mixing them for each standard, the spectral characteristics of each standard and their color coordinates in the international system of color measurements.
3. The equal-contrast classification system is based on the use of a color atlas, in which samples are distributed according to visually equivalent color differences of three color attributes - hue (hue), saturation (eng. Saturation) and lightness (eng. Lightness).

Type of samples

Color atlases are produced various types. Basic:

1. Reflective matte - printed on matte paper.
2. Reflective glossy - printed on glossy paper.
3. Transmissive - colored gelatin filters.

At the request of a number of companies, color atlases are produced on substrates made of metal, plastic and other materials, as well as fabric coloring atlases.

Number of color steps

Usually from 24 to 40.

Sample size

Typically, samples of 1.8 x 2.1 cm and 2.1 x 2.8 cm are used.

Number of samples and examples of atlases

Other Applications

Medical color atlases are used to detect and study color perception defects (color blindness).

Have you ever noticed how some seemingly ordinary photographs literally attract attention? The subject of such photographs is often simple, banal, and there are no special details in the composition as a whole. Such works adorn galleries around the world, earn the admiration of critics, and collectors line up to get their hands on the next masterpiece. As they say, everything ingenious is simple. What is the secret of such “simple” success? Maybe it's the color? The photographer is the same artist. It doesn’t matter at all in what area he draws “inspiration” - events, travel, amateur photography or just a hobby. What matters is how he presents it, how juicy his photographs are. After all, even the most dull and boring landscapes literally come to life in the “hands” of true professionals. And now the “black and white” world began to sparkle with new colors. Here the main role is played by color, which can completely change the perception of the photo.

Color rendition is one of the main aspects when working with a frame. Before moving on to the practical part, first let's try to understand the theoretical aspect a little and understand how a person himself influences his own perception of color.

The concept of color in physics?

Absolutely all light sources have an original color temperature. Some of them produce a yellowish color, others - cooler tones. You need to understand that certain surfaces absorb a different spectrum of light and thus provide an individual perception for everyone.

How does a person perceive eye color?

The fact is that color is perceived strictly individually. This factor is influenced not only by the person himself, but also by the structural features of the eyes, as well as the psyche. Therefore, it is necessary to remember that the same color can be seen differently by two different subjects. The task is also complicated by the fact that the human eye is sensitive to the color palette to a different extent than the camera matrix.

Exploring the color wheel

The color spectrum consists of primary, secondary and tertiary colors. The main components of color are blue, yellow and red. If you mix them in different versions, the result is an expanded range. And when you add black and white colors, you can get their shades.

Monochrome combination

This is the use of shades that are within the same sector of the color palette. In other words, “playing” with the saturation of one color. This combination is especially difficult to portray in a photo, because in reality we have a great variety of colors and shades. This is where color correction comes to the rescue, as well as studio photography.

Complementary colors

In order for a photograph to be pleasing to the eye and radiate natural saturation, it is worth remembering such a concept as complementary colors:

• Collaboration between red and yellow color the output is orange, and the complementary color is blue
• If you mix yellow with blue, you get green. In a complementary version - red
• The union of blue and red will result in purple. Complimentary - yellow.

Once you master the skills of recognizing complementary colors, you will begin to notice them everywhere. No matter what kind of shoot you are doing, it is important that all the colors are in harmony with each other. Therefore, carefully think through all the details before any shooting: what background to photograph the furniture against if you are going to shoot the interior, or what clothes the model will wear best to harmonize with the background, for example.

Triad

A combination in which three colors are equally distant from each other. As a rule, one of these colors acts as the main one (it sets the tone of the photo), the second “supports” the given atmosphere, and the third tries to draw attention to details.

There are other combinations where four, five, or more colors are used. However, beginners should not resort to this technique, otherwise the risk of “screwing up” the whole work is very high. Only experienced professionals who know their craft can make such bold decisions.

Similar colors

Colors that are next to each other on the color palette are called analogous. The combination of such shades will always look advantageous; they will begin to play along with their “partner”.

Warm and cool shades

The circle itself is divided into warm and cold tones. Among the warm ones: red, orange, yellow. The second ones include: blue, purple and green. Cool colors tend to increase space, while warm colors are soothing and can give a feeling of comfort and coziness. This knowledge will help the novice photographer use the properties of the palette to create a successful photograph. For example, to make a photo more dramatic, you can use a cool background for a warm subject. But such techniques are not always successful and are not applicable to all situations.

The thing is that by adjusting the strength of the halogen source, the color temperature begins to reduce its indicators, due to which the light looks warmer.

Color temperature

The first and most important technical point that needs to be remembered: 3200K is the temperature of an ordinary incandescent lamp, 5600K is the temperature of natural light on a fine cloudless day. On modern devices You can set your own white balance parameters using a special gray card. To do this, the frame is filled with a uniform color, after which the setting is memorized by simply pressing a button. The team makes it clear to the technology that the selected color acts as a neutral color, thanks to which the pictures will begin to be adjusted in accordance with this indicator. But the parameter can also be configured manually. Similar actions can easily be carried out in post-processing when working in some formats.

Difficulties

The main difficulty lies in the emission of multifaceted color temperatures when shooting with different light sources. If these very sources that could give an identical color temperature are not available, the use of colored gels is allowed.

The problem is that by adjusting the power of the halogen source, the color temperature decreases, causing the light to appear warmer.

Of course, progress does not stand still, and modern technologies together with the growing capabilities of post-processing programs, they allow you to work outside of rigid boundaries. As mentioned above, “mixing” cold and warm tones is not prohibited, but understanding the mechanism of color temperature in practice will show how it can solve creative problems, and at the same time significantly simplify the post-processing process.

Equipment

The most important thing is where the light comes from, the source itself.In order for color shades to remain in place, a linear spectrum of light is needed,close enough to white. Otherwise, some colors will simply not be visible

1. camera
2. good lens
3. RAW converter

Camera

Any camera has sensors that are sensitive to certain parts of the spectrum. Green colors are a priority, similar to the human eye.

Targets for calibration

One gray card may be enough for beginning photographers. But for professionals there are calibration targets. There is a great variety of them, but here are the most popular ones:

Kodak Q14

It is usually used by professional photographers

Kodak Q60

A difficult target. It controls pastel tones, as well as green and skin tones.

Xrite DigitalColorchecker SGmade of special material. Its price is quite high.

It can be used for:

• testing digital photo reproduction
• relative white point

Digital ColorChecker SGholds as many as 140 fields. Let's consider this factor in more detail:

• Original ColorChecker - 24 fields
• 17 - gray field indicators
• detailed description - 14 unique skin tones
• ColorChecker Passport

Comes with a calibration scale that is easy to use software. Thanks to him, profiles for Adobe are created Camera RAW

Using Xrite Colorchecker

1. Let's say you plan to shoot in a studio with an identical light source. In such a situation, the profile can be prepared once. It will not be difficult for him to adapt to the full spectrum of the light source. The modified spectrum guarantees a similar profile.
2. The situation is different with sunlight. This is where everything depends on the location of the sun above the horizon. The profile works for 2-3 hours, as long as the lighting allows. The picture looks similar when it comes to, let's say, strange light sources, such as fluorescent lamps, ordinary lamps, etc. Each option involves removing the target. But there is a plus - it does not lose its relevance compared to the previous case.

In fact, profiles can be adjusted to the most popular types.

Details:

1. the color checker must be positioned perpendicular to the lens axis and all fields are in focus
2. 10 percent of the frame should be given to colorcheck
3. The color checker also has its own expiration date. Faithfully, it will serve you for at least two years. Otherwise, you yourself will understand when he can retire
4. It is worth paying close attention to the fact that it tolerates exceptionally careful handling, so it is better not to drop it and handle it with clean hands. If you neglect this rule, it will quickly become unusable.

It is necessary to place the model in the place where the photography will take place. Hand her the Xrite Colorchecker with that same gray card. Don't forget that the checker must be perpendicular to the lens. Trying to take a photo.

What other types of calibration targets are there?

There are targets that build a profile, and there are targets that contribute to color rendition. Of course, in the final you should still have a unique original in an adequate and correct color range.

What is the function of additional targets? They seem to bring the color up to established standards. The grass is green, the sky is blue, the sun is yellow. Yes, it's a little boring, but where to go?!

The basis of such targets consists precisely of a set of various familiar standards. Sometimes pictures are far from reality, and that’s when stereotypes come to the rescue, which are more understandable and pleasant for the viewer.

Despite the diversity practical advice, the most best lesson will become your own mistakes. For a beginner who is just getting acquainted with technology, the best option All that remains is to take special courses for beginners, or attend a photography school. Don’t be afraid to experiment, try to empirically discover patterns for yourself. The main thing is not to neglect simple rules and advice, always be in creative search, create your own style and not give up.

Color rendering - the influence of the spectral composition of light on its visual perception

I will interpret this term a little more broadly in this article as getting the “right” colors on the final device/material.

Start

Today I will start one very important and complex topic. It consists of several parts and has a large theoretical basis. I see my task in this case as conveying the most important things to you, but not boring you with too much dry theory.

Theory is good, but we are practicing photographers and therefore must be constantly focused on practical application in real conditions.

Theorists may scold me a little for vague terms (in particular, “color rendition”), but I am a practitioner who has printed enough catalogs, worked with many printing houses and I think I know what is really important and what can be omitted or simplified.

For a photographer, the approach to color rendering is important. Either the photographer achieves subjectively beautiful colors (including those that are beautiful for the customer or those described in the technical specifications) or the photographer achieves the most accurate colors possible.

Even if you are now taking artistic photos for yourself, you still need to know about color rendering, by analogy with an artist, who in any case needs to be able to draw a picture in a classic style, and only then look for his own, possibly very original style.

Human eye

Color is a subjective thing and depends on both physiology and psychology. Color is closely related to a person and the structure of a person's eyes.

That's why first important conclusion: Each person can see a specific color pattern in his own way due to the individual structure of the eyes and mental characteristics. A colorblind person, for example, sees bright red as gray. But perhaps it is not obvious to you that the perception of color is different for absolutely all people within some small limits. Let's call this “production tolerances” :)

Things get even more complicated when you consider that the eyes are not equally sensitive to shades of different colors. Therefore, for example, there are more green photosensitive elements on the camera matrix than red and blue ones. Manufacturers are trying to make the matrix closer in perception to the human eye.

Physical concept of color

There is a color temperature of light from light sources. For example, everyone knows that an incandescent lamp produces a yellow tint, while a fluorescent lamp produces a blue tint of light. And also has the ability various surfaces reflect and absorb a certain spectrum of light. Those. objects begin to have, in a sense, their own color.

The more you illuminate them (up to a certain limit), the more they will light up with a certain color (You will get a source of reflected light. Although we will perceive the object as the final stage in the path of light, in fact, photons from the surface of the object fly directly into our eye and are registered on retina or camera lens and recorded by the camera sensor).

Spectral composition of light

The light spectrum is not always uniform. Man has come up with a lot of different obstacles in the path of light, and therefore we can now receive benefits or annoying inconveniences from this.

For example, the light of the sun is uniform. In addition to the visible spectrum, it contains the UV spectrum, IR spectrum, etc.

The spectrum of light emitted by an incandescent lamp (including a halogen lamp) is also uniform, but with a shift to the red region.

But the light from inexpensive energy-saving fluorescent lamps is inhomogeneous. In some intervals, such lamps do not provide light and therefore you you may lose some shades.

Above is the spectrum of an incandescent lamp, below is a fluorescent lamp

This test is easy to do yourself by looking at the reflection of the light from your lamp on the surface of the CD.

Diode lamps also have an uneven spectrum, although they are better than fluorescent lamps. Moreover, this spectrum depends only on the diode manufacturer.

emission spectrum of a diode lamp

Most lamps are equipped with very cheap diodes with a narrow spectrum. This is a blue LED with a yellow phosphor. The options are different, but getting high-quality light is unrealistic without diligently searching for and checking lamps.

Equipment affecting color

It would be possible to list everything here, but we will focus on the main thing.

Firstly, it is important for us Light source:
1) linear spectrum of light(so that there is no loss of color shades)
2) light spectrum close to “white light”, i.e. light of the full visible range. Otherwise, we also risk not seeing some colors.
So, under water, the red range of the spectrum fades faster and therefore pictures taken without additional lighting always have bluish and greenish tints.

on the left - the color was obtained by exposure to flash light, on the right, everything blue because the flash “didn’t finish off”, but there is no red spectrum. On the right, by the way, I

3) repeatability of light source indicators(for example, an incandescent lamp has a different color temperature while it lights up, a bad flash gives a variation in color temperature from flash to flash)

If I don’t know what color the light will be in the next flash, how will I then understand what color the subject was? Moreover, it will be more difficult to adjust the color balance for the entire series of photographs.

That's why professionals buy expensive flashes with stable color temperature Sveta.

Broncolor studio flash

Simple color control devices

Photography conditions change frequently. In one room there are incandescent lamps, and then you are sent to another room, and there are “energy-saving” fluorescent lamps. We went outside - it was evening and everything was painted blue.

How can we get reliable color rendition and is it necessary?

Some people prefer not to control color rendering at all and leave everything to the camera, believing that this will be more realistic and closer to reality, but just think a little and you will be convinced of the opposite.

If the camera is set to “Auto White Balance” mode, how can it give real white balance values? It identifies each picture anew according to the program programmed into it. Have you seen the code of this program and know how the camera determines the white balance in a room unfamiliar to it, illuminated by a light source unknown to it? The program was written by the programmer of the company that manufactured your camera, and only he himself knows what algorithms he used to determine the white balance.
Take another camera (different model, different manufacturer) and the results will be different. How then can we find truth and mutual understanding with other photographers and future critics of our photographs?
How, after a year, for example, can you guess where in the room the color was gray and where was white? Was the bride's dress white or slightly cream?

Many of these questions are answered by the gray card, which was invented quite a long time ago. Its reflectance is 18% and the color is neutral gray. The gray card is a kind of beacon by which we can roughly align our color balance.

This is what a gray production map looks like Kodak.

Gray Kodak card, 18%

It has its drawbacks since it is printed on regular paper and its reflectivity changes depending on the spectrum of light, but if you are not involved in photographic reproduction, then it may be enough for you. Includes two large cards and one small one. On the reverse side they are white, so you can control the white color.

Roughly shifting the color balance to a more or less correct place is good, but what is in the middle in color space?

Equipment on which the color range depends

1) lens
2) camera
3) RAW converter (Jpeg gives us much less color control. I hope you shoot in RAW)

Lens

The lens may give different shades to the image, may not transmit the full spectrum, etc.
In fact, some binoculars from renowned companies use the idea of ​​cutting off excess spectrum in order to completely eliminate and thereby increase image sharpness. I don’t know whether this method is used in lenses.

Camera

The camera is equipped with a sensor that may be more sensitive to certain parts of the spectrum. As a rule, priority is given to green colors, by analogy with the human eye. The UV and IR spectrum are thoroughly filtered out using a special filter located in front of the camera matrix.

RAW converter

The RAW converter is not a neutral program at all. Just look at the Tone Curve it applies by default.

The default camera profile is Adobe Standard.

Try switching camera profiles and you will be surprised how different they are. We will get to that and build our profiles.

Calibration targets

It is clear that a gray card is enough for an undemanding amateur photographer, but what about everyone else? And then they came up with calibration targets. They are all different, but I will name the most famous and most often used. Knowing frequently used topics is useful because professional calibration software understands them.

This is probably one of the most famous calibration targets. It is suitable for most tasks and is also used by professional photographers, including for photo reproductions.

Q13 differs from Q14 in size.
Currently inheritance Kodak got it partially Tiffen, so you can search for these targets like Tiffen Q13 or Q14. You can find them at bhphotovideo or Amazon.

Kodak Q60 (aka IT 8.7)

This is a highly sophisticated target for controlling pastels, skin tones and greens. It provides much more information and is used by various serious calibration software.

It’s also easy to use by eye, enhancing skin tones, grass, etc.

It is already very difficult to find this calibration target for a reasonable price. As I understand it, this part of the business went to the company Xrite.

Now instead of Kodak Q60 we have (aka GretagMacbeth)

I must say that it is made with high quality, using special material. Its reflectance is very linear across different light spectrums of the light source. But it costs about 400usd (unlike the Kodak Q60, which cost 70usd).

With Digital ColorChecker SG you can:
- Test and compare digital reproduction of both photographs and various test objects
- Set relative white point
- Create a precise ICC profile of a digital camera

Digital ColorChecker SG contains 140 fields selected in such a way as to characterize the color space reproduced by the camera as accurately as possible:
- 24 fields of the Original ColorChecker scale
- 17 fields of gray scale
- 14 unique skin colors for enhanced description of skin tones

Digital ColorChecker SG used with X-Rite i1Match and ProfileMaker 5

It is precisely because of its high cost that I suggest saving money and using their products, but ColorChecker Passport.

Xrite Colorchecker Passport

24 primary colors, gray scale and gray card with reflectivity approx.

Along with this calibration scale comes simple software that allows you to build profiles for Adobe Camera RAW.. It is enough to take a normally exposed target, convert it from RAW to DNG and feed it to the Colorchecker Passport program. At the exit you will receive color profile for ACR, which will automatically integrate ( Adobe Photoshop will need to restart).

With faded colors - profile Adobe Standard. On the right - profile by Xrite ColorChecker Passport.

Now let’s imagine a typical example - you need to photograph something so that you can later know exactly what color it was.

Such an example is any natural object. Here, for example, are various stones.

Notice how the colors of the stones change. If I had not used a calibration scale, I would never have been able to tell what color the stones actually were (amber).

As you can see, all the bluish tints are gone and the bright colors have found their saturation (precisely their own, and not additional). This is very good, but as you understand, it’s not enough to bring 24 colors up to the original. So a large target is very useful for building a profile. If there is no desire to achieve the ideal, then Colorchecker Passport compact and useful tool.

I note that for proper operation(to see its benefits with your eyes) of the calibration scale, you must also have a calibrated monitor. But! It is very important that you can calibrate the monitor later, just like any printer on which you are going to output your photo. But it is advisable to get a color profile for a photo at the very beginning, otherwise the rest of the process does not make sense and you will do everything in an indistinct way, called “by eye”.

How to use Xrite Colorchecker

1. If you are shooting in a studio with the same light sources, then you can make the profile once. It allows you to adapt to the spectrum of the light source. The spectrum is unchanged - the profile is the same.

Sunlight is another matter. The spectrum of sunlight changes depending on the height of the sun above the horizon. The profile can be made for the next 2-3 hours, until the lighting has changed significantly.

The same thing with unknown light sources, such as fluorescent lamps, fluorescent lamps, etc. For each lighting option, you need to remove the target. Another thing is that it does not become obsolete, as is the case with the sun.

in fact, you can “sin” quite strongly against these rules. It all depends on how accurate you still need the color rendering.

2. you can build profiles for the most commonly used types of lighting. For example, “an incandescent lamp in my home,” “fluorescent lighting in a shopping center,” etc.

It will be more difficult if there are combinations of lamps. This is just a “pipe” and even the passport color checker will not fully save you. A larger target will work better. But in such situations, they either put up with incorrect color rendering if this is a photo for themselves or use filters that normalize the lighting.

Nuances:

1) the color checker must be positioned perpendicular to the lens axis and all fields are in focus

2) the frame must be well exposed, without any tightening in Adobe Camera RAW!

3) the color checker in the frame must occupy at least 10% of the area (preferably more)

4) the color checker has an expiration date. like two years... but then you can decide for yourself when he became worthless. The Kodak card is not neutral at all.

5) Please note that it gets quite dirty if you drop it or grab the color swatches with dirty hands. This cannot be done - it will not be suitable for use (it cannot be washed).

3. You place the model in the place where you will photograph it. First, you give Xrite Colorchecker to your hands with a large gray card (it’s convenient to set the white balance later). The checker is perpendicular to the lens. take a photo.

Then you open the side where there are 24 color samples and also take a photo.

photo from my masterclass at the Kronstadt forts

At home you open files with a checker in Adobe Camera RAW(there seems to be a plugin in Lightroom, but I don’t use it. It’s not important). From the initial menu, without touching any sliders, save it to DNG. Open the ColorChecker Passport program. Drag the DNG file with the checker into its window. The program will rustle and give you certain color squares and highlight them. If she makes a mistake, it’s easy to adjust manually. Then click “save profile”.

Restart Photoshop and there it is - your profile in the menu ACR(picture in the article where “camera profile”.

I recommend determining white balance from the file where your color checker will be open with a large gray field (58% reflection, very stable readings). ACR is poorly oriented in small fields - data from neighboring dark squares differs (it seems ACR does not like to determine white balance from very light and very dark cards). Data on the gray card kodak they walk stronger than Colorchecker's anyway.

That's it, you're ready to process your photos!

Set the white balance you define, apply the profile, enjoy the results (no more guessing what color was what).

P.S. You can selectively edit your profile, but I hope you won’t need it

P.P.S. Colorchecker Passport not a panacea! It has only 24 colors and they are bright! If you want to be more precise, take a large target, there are flesh colors, green colors, etc. You will adjust your profile much more accurately to the truth. but costs $$

Other types of calibration targets

In addition to calibration targets that allow you to build profiles, there are also targets that allow you to make your own subjective contribution to color rendition. It is advisable at the final stage that you always have the color-correct original.

So, these additional targets allow you to bring the colors up to the common and standard ones. The generally accepted and standard colors of skin and grass are like the average temperature in a hospital. It doesn’t make sense, but if you want, then here’s a “spherical European in a vacuum.”

The targets are based on the skin colors of Europeans, Asians, blacks, etc. As well as grass, wood and other commonly found flowers.

Despite the resulting unnaturalness of colors, sometimes it is more convenient to work with “standard” skin tones and other “standard” colors that the viewer is accustomed to and accepted.

This is what these targets look like.

Although personally I would prefer such a target...