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AdobeRGB or sRGB which color space to use. Color Profile and Spaces: Basic Concepts

Color space is an abstract mathematical model, describing a certain color palette, i.e. fixed range of colors using color coordinates. For example, palettes built using the additive RGB scheme are described using a three-dimensional model, which means that any color included in the palette can be uniquely determined by an individual set of three coordinates.

The most complete color space– CIE xyz, covers the entire spectrum visible to humans colors. In 1931, the International Commission on Illumination (Commission internationale de l'éclairage or CIE) approved CIE xyz as the reference color space, and therefore it is still used to this day to evaluate and compare all other models.

It is important to remember that not a single device used to reproduce color images, be it a printer or a computer monitor, is able to display all the variety of colors that is available to a person with normal vision. Worse yet, the color gamut of different devices often does not match, as a result of which the same colors may appear differently depending on the specific model of monitor or printer. To solve this problem, so-called working color spaces, which are standard palettes that more or less correspond to the color gamut of a certain class of devices. Using standard color spaces when working with a color image makes it possible to ensure that you do not exceed the color range of the final output device, and if output is unavoidable, you can learn about color space mismatches in advance and take appropriate action.

Working color spaces

The most commonly used working color spaces in digital photography are sRGB and Adobe RGB. ProPhoto RGB is much less popular.

sRGB

sRGB is a universal color space created jointly by Hewlett-Packard and Microsoft in 1996 to unify color reproduction. sRGB is far from the widest space - it covers only 35% of the colors described by CIE, but it is supported by all modern monitors without exception. sRGB is the global standard for displaying images on the Internet, and all web browsers use this color space by default. When you save an image in sRGB, you can be sure that the colors you see on your monitor will appear on other monitors without significant distortion, regardless of the program used to view them. Despite its apparent narrowness, the sRGB palette is sufficient for the vast majority of practical needs of an amateur photographer, including photography, photo processing and printing.

Adobe RGB

In 1998, Adobe Systems developed the Adobe RGB color space, which more closely matches the gamut available on high-quality color printers than sRGB. Adobe RGB covers approximately 50% of the CIE color gamut, but the differences between Adobe RGB and sRGB are difficult to distinguish by eye.

Side-by-side comparison of the sRGB color range (color region)
and Adobe RGB (light gray area).

It should be understood that thoughtlessly using Adobe RGB instead of sRGB, due to the abstract superiority in color gamut, not only will not improve the quality of your photos, but will most likely lead to its deterioration. Yes, theoretically Adobe RGB has a larger color gamut than sRGB (mainly in blue-green tones), but what's the point if in 99% of cases this difference is not noticeable, neither on a computer monitor nor when printing, even with the right equipment and software?

Adobe RGB is a highly specific color space used exclusively for professional photo printing. Adobe RGB images require special software for viewing and editing, as well as in a printer or mini-photo lab that supports the corresponding profile. When viewed in programs that do not support Adobe RGB, such as Internet browsers, any colors outside the standard sRGB color space will be clipped and the image will appear dull. Likewise, when printing in most commercial darkrooms, Adobe RGB will be poorly converted to sRGB, and you will end up with less saturated colors than if you had originally saved the image in sRGB.

ProPhoto RGB

Due to the fact that the entire range of colors perceived by a digital camera sensor is so wide that it cannot be directly described even using Adobe RGB, Kodak proposed a new color space, ProPhoto RGB, in 2003, covering 90% of CIE colors and less. -poorly corresponds to the capabilities of the photomatrix. However, the application value of ProPhoto RGB for a photographer is negligible, since no monitor or printer has a sufficient color gamut to take advantage of the ultra-wide color space.

DCI-P3

DCI-P3 is another color space proposed in 2007 by the Society of Motion Picture and Television Engineers (SMPTE) as a standard for digital projectors. DCI-P3 simulates the color palette of film. In terms of coverage, DCI-P3 is superior to sRGB, and is approximately equivalent to Adobe RGB, with the only difference being that Adobe RGB extends more into the blue-green part of the spectrum, and DCI-P3 into the red. Anyway, DCI-P3 is interesting for the most part for cinematography, and is not directly related to photography. Among mainstream computer monitors, it seems that only Apple iMac Retina displays are capable of correctly displaying DCI-P3.

The choice of color space should be based on specific practical considerations, and not at all on the basis of the theoretical superiority of one space over another. Unfortunately, much more often the scope of the color space used by the photographer correlates only with the level of his snobbery. To prevent this from happening to you, let's consider those stages of the digital photographic process that may be associated with the choice of a particular color space.

The actual shooting

Many cameras allow the photographer to choose between sRGB and Adobe RGB. The default color space is sRGB, and I strongly advise you to leave this menu item alone, regardless of whether you're shooting RAW or JPEG.

If you shoot in JPEG, then most likely you do it to save time and effort, and you are not inclined to tinker with each image for a long time, which means Adobe RGB is definitely of no use to you.

If you shoot in RAW, then the choice of color space does not matter at all, since the RAW file, in principle, does not have such a category as color space - it simply contains all the data received from the digital matrix, which will only be compressed during subsequent conversion up to a given range of colors. Even if you plan to convert your photos to Adobe RGB or ProPhoto RGB, you should leave your camera settings at sRGB to avoid unnecessary hassles when you suddenly need in-camera JPEG.

Editing

The standard color space is only assigned to an image when the RAW file is converted to TIFF or JPEG. Up to this point, all processing in the RAW converter occurs in a certain conditional non-standardized color space corresponding to the color gamut of the camera matrix. This is why RAW files allow you to be so free with color when processing them. Once editing is complete, colors outside the target palette are automatically adjusted to the closest values within the color space you selected.

With few exceptions, I prefer to convert RAW files to sRGB because I want results that are extremely versatile and reproducible on any hardware. I'm quite happy with the colors I get in sRGB and find the Adobe RGB space to be redundant. But if you feel that using sRGB negatively affects the quality of your photos, you have the right to use the color space that you see fit.

Some photographers prefer to convert files to Adobe RGB in order to have more freedom when post-processing the image in Photoshop. This is true if you are actually going to do deep color correction. Personally, I prefer to do all my color work in a RAW converter, because it is simpler, more convenient and provides better quality.

What about ProPhoto RGB? Forget about him! This is a mathematical abstraction and the feasibility of its practical application is even lower than that of Adobe RGB.

By the way, if you still have to edit images in Photoshop in spaces other than sRGB, do not forget to use 16 bits per channel. Posterization in larger gamut color spaces becomes noticeable at equal bit depths earlier than in sRGB because the same number of bits are used to encode a larger range of hues.

Seal

Using Adobe RGB when printing photos can be justified, but only if you are well versed in color management, know what color profiles are and personally control the entire photo process, and also use the services of a serious darkroom that accepts Adobe RGB files and has the appropriate equipment for printing them. Also, take the time to run some tests, converting the same photos to both sRGB and Adobe RGB and printing them on the same hardware. If you can't tell the difference, is it worth complicating your life? The sRGB palette is enough for most scenes.

Internet

All images intended for publication on the Internet must be in mandatory converted to sRGB. If you use any other color space, the colors may not appear correctly in the browser.

If I haven't expressed my position clearly enough, let me repeat it again: if you have the slightest doubt about which color space you should use in a given situation, choose sRGB and you will save yourself from unnecessary hassle.

Thank you for your attention!

Vasily A.

Post scriptum

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Adobe RGB is a color space created to better represent colors during the printing process. In this article you can learn some interesting things about color and color spaces, and for the lazy ones there is a short summary at the end of the article.

What is color space?

A color space, in general, is the range of colors that can be displayed on a computer monitor, printing, or other display process. Color spaces often differ in their scale (spectrum) - in other words, in the number of colors indicated in them.

This can be illustrated by the transition between green and blue, that is, where differences between individual color spaces most often arise.

The smaller color space attempts to reproduce all the colors in its area—green and blue—but the green is less clear and intense than the larger color space. There is a whole range of shades of green and blue that are not generally found in a small color space.

What are RGB, SRGB and Adobe RGB?

The basis is regular RGB, that is, all possible colors that your monitor or TV can display. RGB space is the simplest of the three. It includes all color combinations that can be displayed on professional monitors. The same RGB image will look slightly different on different devices, but most people don't notice this.

Space SRGB describes the common range of colors between computer monitors and printers, works similarly to the RGB color space, which is the same for all monitors, so is best choice for photographs and graphics published on the Internet. The SRGB format was created in collaboration between Microsoft and Hewlett-Packard two years before Adobe's release. The SRGB format describes a smaller color range than Adobe RGB.

Adobe RGB is one of the three color spaces that every photographer knows. The Adobe RGB color space was developed by the creators of Photoshop in order to be able to reproduce on a computer monitor a color gamut close to that which is output when an image is printed on a printer. The print result is created in the CMYK (cyan, magenta, yellow, black) color space. Adobe RGB describes a wider range of colors than SRGB and RGB.

The diagram above describes the perception of color by the human eye. The shaded area is the colors we can see, and the marked triangles are the range of colors that can be reproduced using the SRGB and Adobe RGB color formats. In the shaded area, the proportions of primary colors are not equal, because the human eye has a minimum of receptors sensitive to blue color, and a maximum of receptors responsive to green color. The graph represents the CIE 1931 color model at 50% brightness.

Adobe RGB space gives the greatest advantage in light colors, where (which is not visible in 2D graphics), in addition to green and cyano (blue-green), there are complementary shades of yellow and red, for example, giving a greater range of colors in sunrise photographs. With darker tones, almost only shades of green predominate. Blue color remains unchanged relative to SRGB at any brightness. On average, SRGB space reflects about 35% of the colors that the human eye sees; for Adobe RGB this figure is about 50%.

Differences between SRGB and Adobe RGB

Using Adobe RGB

However, in order to get any real benefit from Adobe RGB you must have a printer that is compatible with this color space. Most inexpensive printers, even those specifically designed for photo printing, are not capable of covering the entire SRGB color gamut and only a very small portion covers the Adobe RGB space. Printers in the higher price range can take advantage of Adobe RGB capabilities to some extent, but be aware of using genuine inks, suitable paper and using the ICC profile (Adobe RGB profile)

Of course, if you want to use Adobe RGB for better color reproduction, then you must properly calibrate your computer monitor, which in turn may change the Adobe RGB colors.

Should you use Adobe RGB?

The short answer is no. Of course, Adobe RGB can, with appropriate calibration of the monitor and printing, give top scores than SRGB, but this almost always comes down to theory. There are very few photographers who use Adobe RGB, and the differences between the effects in any color space are incomparably less important than properly calibrating the monitor or DSLR for printing. The differences in results when using tools like ColorChecker Passport, Spyder 3 Pro or ColorMunki will be much more important than choosing one color space over another.

As practice with students has shown, the question the right choice color space is very relevant when processing images in Photoshop.

Most, having listened to the recommendations of numerous gurus that real Jedi work only in Adobe RGB or ProPhoto RGB, set up Photoshop to work in wide color spaces, without really understanding both the advantages and disadvantages thereof. They don't even want to hear about the sRGB space.

When asked about the reasons for choosing this particular color space, few can give a sufficiently intelligible answer. Typically, the most common answers about wide color spaces come down to just the width of the color gamut, that is, the ability to produce brighter and more saturated colors, as well as greater precision in color control.

In fact, in the case of using wide color spaces, the accuracy of working with color, or rather, its accuracy mathematical description, is just suffering. The fact is that Photoshop, like any computer program, operates with discrete data. That is, for example, 256 gradations of brightness per image channel will more accurately describe a narrow color space than a wide one.

In other words, in a wider color space the risk of visible posterization of the image increases. This is especially true for the ProPhoto RGB space, as it has the widest color gamut.

In order to consciously choose a color space for work, you need to take into account both the scene being filmed and the capabilities of the equipment for viewing and printing the image and the purpose of the processing itself.

Let's look at this with practical examples.

Let's start with the actual scene or plot being filmed. If you shoot primarily portraits, for example, there is no need for a wide color space, since the image will certainly not contain colors outside the gamut of the sRGB color space.

On the other hand, when shooting landscapes, sometimes there may be a situation where the scene you are shooting will contain colors that fall outside the gamut of sRGB.

The examples below show a fragment of a sunset photograph, with areas outside of sRGB shown in red. In a photo converted from a RAW file to the Adobe RGB color space, there is no out-of-color gamut observed.

Here you already need to think about the ability of the equipment to display Adobe RGB colors. As a rule, fairly expensive monitors with an extended color gamut can adequately display them. If your monitor is not one of these, there is no point in using Adobe RGB, since you will simply be working blindly, without seeing the real picture. As a result, when printing, you may see colors that are completely different from what you saw on your monitor.

If you are going to print photographs on high-quality professional machines capable of printing such a wide range of colors, then you definitely cannot do without an appropriate monitor.

If you do not print images in expensive laboratories, but mainly in budget minilabs, or do not print at all, but process them for displaying photos on the Internet, it also does not make sense to work in a wide color space; you need to immediately process in sRGB.

Here I am not considering working in Adobe RGB to prepare images for printing. The people who do this already know everything very well.

The scene you are shooting contains colors outside the sRGB gamut
The monitor is capable of displaying Adobe RGB colors
The printing device is also capable of reproducing Adobe RGB colors

As a rule, for amateur photographers with budget equipment, the last two points are not met. Consequently, working in Adobe RGB will not provide any advantages, but, on the contrary, will result in unnecessary problems.

If for some reason you still work in Adobe RGB, without really understanding why it is needed, then in order to avoid problems with color when viewing images by other users, as well as when publishing on the Internet, before saving the image in JPEG format, you should Convert to sRGB color space.

Also, many people ask the question: what color space should I choose in the camera settings?

If you shoot in RAW format, this does not matter, since the color space or profile is set during conversion. So choose sRGB.

If you shoot in JPEG format, then in most cases it is better to also choose the sRGB profile. This is due to what I wrote above - the accuracy of the digital representation of color space. For sRGB it is slightly higher, therefore, during subsequent processing, the risk of posterization is reduced.

The article describes how to set up Photoshop for working with photographs.

Probably many of us, poking around in the camera settings menu, paid attention to the item called “ Color space“. Typically, the user is offered two options for this setting - sRGB And Adobe RGB. What is it and what is it eaten with? Let's look under the cut.

Let's start with what both formats have in common - RGB prefixes. In fact, it is an abbreviation for the three primary colors visible to the human eye - red, green and blue ( red, green, blue). All other colors that we see are formed on our retina by mixing these three colors.

What is color space? In simple words, this is the set of colors that we can see. Even simpler - this is a digital model for describing colors. To make this term easier to understand, a diagram was compiled in 1931 that clearly shows us the RGB space:

CIE 1931 mathematical diagram describing RGB

Each color in this diagram has its own point on the coordinate system. Each of these points is responsible for a color component in the decomposition into red, green and blue.

With the emergence and release of digital photography and video to the masses, the issue of color display has become especially acute. After all, the matrices of modern devices see the color palette more widely than the human eye. And I had to think about how to transfer the image to the screen for subsequent viewing and processing.

We thought about it and decided that we needed a separate profile that would be used by information output devices. This profile was described in the 1990s and was called sRGB. In the CIE 1931 chart, the sRGB color space looks like this:

As you can see, the sRGB triangle covers only a small part of the spectral palette visible to our eyes. But we should not forget that the capabilities of technology in the 90s of the last century did not allow us to cover color more widely. The sRGB profile was created specifically to display images correctly on inexpensive monitors.

Since then he has been the main one. Most modern monitors and browsers are designed for this color space, but what can I say - the sRGB color space is the main one for Windows systems and for the photo editor Photoshop.

Profile Adobe RGB was developed in 1998. Initially, it was made specifically for HDTV (high-definition television). It covers a large spectral palette:

But more is not always better. Remember that most modern technology and programs support the sRGB color profile? Therefore, do not be surprised if your photo is criticized for strange shades appearing or when printing it the colors turn out to be distorted. This profile is designed primarily for professionals who are involved in serious post-production of photographs. They have in their arsenal professional monitors and printers that support the Adobe RGB profile. You can just work in this color space, but is it worth it if most people won’t see your photo the way you wanted to show it due to compatibility issues.

So amateur photographers benefit from the first option when choosing a color space. Why? There are several reasons.

Firstly, if you are going to publish your photos on the World Wide Web, you should consider that most modern browsers work in sRGB. And in order to avoid problems with shades of the wider Adobe RGB profile popping up from nowhere, shoot in sRGB.

Secondly, copy centers and photo laboratories configure their equipment for this profile by default. The vast majority bring photos in exactly this color profile.

Thirdly, the use of Adobe RGB on non-professional monitors distorts the color rendition of photographs and can make them more faded and dull. Those. does not reveal their potential at all.

Therefore, feel free to set it in your camera settings “Color profile – sRGB” and shoot for your own pleasure. And yes, remember the most important thing: the color space in the camera is set only for JPEG files. If you shoot in RAW, the color space will be assigned during the conversion process of RAW files directly during processing.

As practice with students has shown, the issue of choosing the right color space when processing images in Photoshop is very relevant.

In fact, in the case of using wide color spaces, the accuracy of working with color, or more precisely, the accuracy of its mathematical description, suffers. The fact is that Photoshop, like any computer program, operates with discrete data. That is, for example, 256 gradations of brightness per image channel will more accurately describe a narrow color space than a wide one.