Colour Profiles
Key vocabulary to remember
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Introduction
Colour Profiles are a highly important part of the photography workflow. They are a set of conditions that govern the way in which a particular device interprets colour. Any device we use to capture or show an image, including our eyes have specific characteristics that influence how an image is perceived. During our technological evolution and based on limitations of displays, cameras and printing technology, common rules to describe colour have been designed. Many decades have passed and results may still not be entirely consistent. However, we should be aware of areas where we can consistently reach good results.
Inconsistent results
Unfortunately, colour profiles are frequently omitted from discussion due to the fact that acceptable results are frequently achieved, on the one side, and due to the fact that colour profiles are, unfortunately, still rarely consistent on platforms. As there are few possibilities of accurately simulating how a photograph looks on the intended publishing medium, most of the work is centered on compensating for various noticed limitation in the edited image. This is time consuming and an non-ideal approach that is best avoided.
Current PC configurations as well as most programs can and do respect colour profiles. Unfortunately, colour consistency, or the ability to show predictably the same intensity and saturation is not a common concern for software development. The operating system, whether we consider Linux, Windows or MacOS, tries to create and include a centralized way to manage the output on the screen through its control panel settings. However, there are limitations on how the colour profile is imposed on the way in which images are displayed and this occurs particularly if the graphics applications use non-standardized ways of displaying images due to performance or ability goals.
Note that even if all guidelines are followed strictly, there may still be many situations where colour is not accurately processed. The suggestions presented in the document refer to best practices that vastly improve predictability.
Types of Colour Profiles
Display
The most likely colour profile to encounter is for displays. As the final element to showcase an image and the reference on most, the display is essential on all scenarios. Unfortunately, due to different technologies and variation in product lineups, few displays from different manufacturers are highly comparable, yet many more will be present and used to evaluate the quality of photo creations. This is the main reason why content creators frequently choose to exaggerate their creations, particularly in colour and contrast, so that they will be able to show reasonably well on different display.
Display colour profiles are used to define how each point in the image is to be represented on the screen and represents a computation that is applied based on the initial information supplied, such as your photo's content. Even in the absence of a colour profile, there is an implicit translation that is applied, ending with reasonable output in all circumstances. Of course, absent any particular support from the display manufacturer, this is the most likely result. However, most manufacturers ensure that computers, as they are used for editing images, are supplied with improved abilities to maintain consistency. This is the reason that displays are supplied with colour profiles which are by default installed and activated on computers nowadays, no matter if you use Windows, MacOS or even some Linux distributions.
All displays conform to at least a minimum colour profile, such as sRGB, the standard that is central to the PC and web development for a long time. Note that conformation does not translate into the accuracy that you may expect and this is the flaw that you may spot most frequently, such as colours not looking right, in spite of any configuration.
sRGB
The most common colour profile and the one you should aim for in most situations is the sRGB one. Standardized in 1999, it is the format to which all manufacturers of displays and software cater to. Basically everything that is published on the internet is aimed at this standard. Although it is slightly older, the colour profile is reasonably expected to be reached and even superseeded by most manufacturers, creating a common platform expectation that should be targeted by any graphical creation.
It is true that the colour profile was designed when Cathode Ray Tubes where the standard display technology of the time, but it is well suited even for modern ones such as OLEDs, as well as the popular LCD ones. In many ways, it is true that such a colour profile may not accurately represent the abilities of your or your viewer's particular display. However, the fact that it is consistently available and applied, leads to predictable results and this is the main concerns when you aim for high quality photography.
An important fact to remember is that any colour profile presented below is larger or wider than sRGB, but fewer displays may be certified to reach such a good performance. Nowadays, some display manufacturers may not mention that they certify their products for the sRGB profile, but they are certainly respecting established guidelines. This is the main reason why, despite all technological advances, sRGB is still relevant or the basic standard that you should always aim for, unless specific requirements are imposed.
The sRGB profile is a minimum standard that is always respected. Results may not be satisfactory in how it is implemented and, unfortunately, no display on turn-on can display images with good accuracy, as there are many settings that are wrongly made to reach what the manufacturer thought as being desirable to the public
Adobe RGB and other standards
Adobe, a well-known American company, has been highly active in promoting their own standards that attempted to reach consistency in software they were promoting and to achieve high market penetrations. Unless specifically directed to use such a profile, you should use the sRGB one to achieve results that are easily predictable on most displays and software.
DCI-P3
This very high specification is reserved for very high quality displays. Due to current technology abilities, the only highly-available mass market product to incorporate it is OLED screen, with few LCD displays also available to reach these high specifications. Note that such a colour profile does not translate in any special ability to edit or see the images in a revolutionary way, it just means that the display could potentially display images requiring such colour profiles with good accuracy. As very few images and software actually require such capabilities, the DCI-P3 certification is important mostly to ensure that images can be always shown with accurate colours when required for less demanding editing, such as the ones that cater to sRGB and lower demand colour profiles.
Note that a DCI-P3 display may be present in a laptop, on a tablet or any device that may not be configured right away to display accurate colour. The end user is expected to be more attracted due to extremely vivid or over-saturated colours than an accurate representation of them. You may have to make extensive modification to disable or adjust saturation and contrast enhancements in the software that accompanies your computer, in graphical settings, to reach accurate results. You may also need to watch reference images and adjust these settings manually if you do not have colour calibration equipment available.
The above mention is extremely important as you do not have an out of box, simplified experience of accurate colour display even if you invested in costly or high specification equipment. You still need to adjust it to more accurately represent its capabilities. Keep in mind that this is the only way to achieve very good results and what matters is that you have a product that can reach the desired specifications instead of a cheaper one that will never be able to and offer more frustration when expected to behave accurately.
DCI-P3 standard conformance on displays and specialized equipment is a good indication of high accuracy. While professional equipment is delivered with standard settings, consumer one has to frequently be reconfigured by disabling various features that alter the image to be more appealing to the public, but both can reach similar results.
HDR
There is no such colour profile as HDR or High Dynamic Range. There are, however, colour profiles that are suited to achieve the desired results of HDR, such as the BT.2020 standard. All HDR capable devices such as cameras and displays, must be able to conform to specific requirements to be able to generate and display accurately the high dynamic range required for such images. As you will clearly note, however, cameras do not conform to specific colour profiles which means that only displays have to abide such rules.
Working and displaying HDR pictures does have some specific requirements. If most images nowadays have 24 bit colours, or may be presented as 32 bit if they include an Alpha or transparency channel, HDR requires at least 10 bits per colour channel or as much as 16-bit. Modern OLED screens can display images with 10 bit colours but the majority of economy LCD screens are not able to do so, or they are not as accurate when displaying in these conditions. This means that, at least for a while, reaching consistent results with HDR images is the most difficult limitation rather than having images or displays that can have the minimum capability exposed.
An important note is that HDR display conditions are, unfortunately, at least in Microsoft Windows operating systems handled poorly but neither Apple MacOS or Alphabet's Android handle the situation as required. An HDR colour profile should not be activated unless the image has such particular requirements and only for the area that is the cause of such requirement. This may mean that the rest of the screen should still display images in the standard colour profile. As colour profiles are, unfortunately, always applied for the entire display output, results are compromised.
Images that have no HDR information may look slightly exaggerated in contrast and brightness or the same can be said about standard images being muted when viewed while an HDR colour profile. The end result is that we hardly have a reasonable grasp on how HDR images should look and most pictures that may seem to be conforming to the HDR moniker may just be standard ones, edited to achieve a certain look.
The best approach is to try and maintain most of the initial image characteristics and drop the colour information to the 24/32bit or 8 bit per colour system only at the last stage of editing.
For most intents and purposes, HDR does not act as a standard but more as a marketing desire to promote better technology. As there are no strict requirements to follow, HDR images are frequently above or below expectations, depending on creativity and products performance. No camera conforms to a specific display to produce consistent results.
Colour temperature
All colour profiles specify a colour temperature. The notion is centered around the concept of an ideal black-body or thermal radiator radiating light at a specific temperatures, with the lower temperature casting an orange glow while the higher ones showing a blue or violet appearance. In practical terms, this approximation is used to express how yellow or blue white objects look when under this light. The appearance of colour objects is also shifted towards a yellow or blue appearance. The most common colour temperature is 6500 Kelvin, which is described as Daylight, and abbreviated D65. Warmer appearances such as warm white can be reached at around 3000Kelvin while cold appearances are reached over 7000 Kelvin colour temperature. Modern LED light sources can easily create these conditions indoors, as required, and some light sources can even generated custom white light tints or colour light, which does not conform to this white light and colour temperature standard.
Colour temperature is important as artificial light and natural light behave in completely different ways. Natural light colour temperature varies throughout the day, being "warmer" at sunset and sunrise, colder at midday and relatively balanced in the rest of the time. Note that the presence of clouds, fog or clear sky also alters the colour temperature, clouds and fog making the colour temperature rise while a clear sky lowers slightly the colour temperature.
Daylight colour, the D65 standard
You may wonder why colour temperature is important. The reason is very simple: ideally, you should be able to see your image in the same condition it was taken in, and edit it while you experience the same conditions. Our eyes adapt well to different conditions while cameras, displays and any device does not do so by default or does not act as seamlessly. It is obvious that this is not possible to fully reproduce. In most circumstances, you have to consider a typical editing and image viewing condition that considers a daylight setting, at a colour temperature of around 65000 Kelvin. This means that your display must not be overly dim, have altered colour saturation or major distortions that influence the end results. For a good measure the picture has to be still visible and look reasonably well in intense and dim light situations.
The 6500 Kelvin colour temperature is a standard that has to be remembered, a reference for your creations. While many devices may not have, be configured for or allow such conditions, it is expected that in places that matter, such as exhibitions, on professional equipment, you have to be experienced in reaching it.
Colour profile use
Microsoft Windows
It is essential to use a specific colour profile not only in windows but also in Windows applications. The first requirement is to properly set the default colour profile, while for other software there are individual settings that must be found in the documentation that comes with the program or that can be found on the internet.
Open the Start menu and type "color management". As soon as the first letters are typed, there will be an application that appears with this name. Launch the application, note the tab or section labeled "Advanced" and note the settings that appear on the window.
The most important setting is the "device profile". While it is expected that the current profile, probably one that has a name that includes the monitor or display name of your computer is the correct choice. However, for a context that can be easily compared on multiple devices it may be more helpful to change the device profile to a well used profile, the one of your display. The full option settings are presented briefly, the reasoning for these choices is due to achieving the best possible balance between practical and ideal accuracy. The settings below establish particular options for different scenarios.
Device profile: Your Display Name and Model
Viewing condition profile: System Default (WCS profile for ICC viewing conditions)
Default rendering intent: Absolute colorimetric
Perceptual (photo images): Proofing - simulate paper/media color
Relative Colorimetric (line art): Proofing - simulate paper/media color
Absolute Colorimetric (simulate paper): Proofing - simulate paper/media color
Business Graphics (charts and graphs): Proofing - simulate paper/media color
Note that there is also the capability to press the Calibrate Display Button, that will bring a different set of tests to evaluate the default profile results and/or adjust the profile. It is advisable to look for more information before adjusting the profile, as some settings may severely affect the accuracy of the image shown on the display more than a less suited default colour profile. These settings will be applied to all applications running on the computer, including video players and games which means it is important to understand their purpose.
Apple MacOS
One of the major advantages of using the Apple platform is that many settings are, by default, chosen for you, the user. Apple devices may not have the best displays but they are certainly set in a consistent manner that leads to predictable and consistent results across a lot of products. Such a seamless integration is part of the reason why many photographers, content creators and visual artists use the Apple platform. It is possible to reach the same results in Windows or Linux, although it is certain that you need to make particular settings active instead of the default one.
In case you need to change the colour profile or make sure that it is correctly set, open the Apple menu, the one having the Apple icon, on the upper-left corner, click on the "Systems Preferences" menu option, and click the "Display" icon to open the display settings. The window presents a couple of options and the one of interest is in the "Color" section. The active colour profile can be selected from a list that comprise many different choices. The one that should be active by default should be "Colour LCD".
A new colour profile can be created, if required, by pressing the "Calibrate..." button. A couple of dialogues will appear that allow changing settings to adjust the colour profile of your display to your preferences. It is advisable to look for more information before adjusting the profile, as some settings may severely affect the accuracy of the image shown on the display more than a less suited default colour profile. These settings will be applied to all applications running on the computer, including video players and games which means it is important to understand their purpose.
The out of box or standard user experience on an Apple Mac and other Apple devices is more consistent as the user has nothing else to do but just use the equipment and it is already well-enough configured. Windows or other operating system users have to extensively configure their system to reach same results but the potential is similar.
Graphics and Image Editors
Krita
In many ways, Krita is an extremely popular image editor, the best open-source software for creative photo editing. It is much easier to use than GIMP, free compared with the traditional software for Image Editing, and it is available both for Windows and Linux. While not offering the same capabilities and extensions or plugins as Adobe Photoshop, the most versatile image editor, Krita fares favourably well for more experienced users, while it may be somewhat more difficult to work with for first users. However, ease of use depends on features and Krita frequently makes learning about such capabilities worthwhile. It is also possible to use Krita for basic image editing as well.
Krita is, perhaps, the most versatile open-source, free image editing application you will encounter. While not as feature full as commercial software, getting familiar with Krita is simple and learned techniques will be valuable on any software.
GIMP
GIMP was, until recently, the only open-source software that may come close enough to the capabilities of Adobe Photoshop, before Krita evolved. The software was first developed for Linux and later expanded to also cover Windows. While powerful in itself, GIMP does not adhere to the standard menu-driven operation as other programs, making it slightly more difficult to use than well-known image editors such as Adobe Photoshop. Due to its long presence on the market, there is a very large variety of tutorials that are help to get you accustomed to GIMP.
Adobe Photoshop
Adobe Photoshop is the golden or most popular image editor software. While it is a commercial application and is relatively expensive, counting at more than 200 Euros or USD per year for a single license, Photoshop is the widest use software for image editors. It is much more powerful than what most individuals need, being useful particularly for advanced users or the ones that require specific functionality, features, effects or the ones that require particular plugins to work with. As a rule of thumb, you may not need such a software application, although understanding the logic and operation of Adobe Photoshop creates expectations and improve your chances of adapting to concepts used in just about any image editor.
One of the features that is applied thoroughly in Adobe Photoshop, regardless of the operating system, is the ability to simulate particular colour profiles, on the fly. Such a feature is useful to determine how certain images may end up looking when printed. For instance, in the typical CMYK colour gamut of a printer, the image may look totally different from the perfectly fine and vivid in sRGB, as the colour profile used by all displays.
Adobe Photoshop is a highly expensive commercial image editor. As it is used by professionals for decades, there is extensive documentation and tutorials to achieve just about any result. However, most editing can be done reasonably well by ambitious users in software such as Krita, that is free of charge.
Web browsers
We may not be aware that most web browsers do not respect the same colour profiles as expected, by default, showing any image with slightly more muted colours than it may be expected. This is a common occurence, caused due the insufficient interest in developing consistently the application support for colour profiles and enforcing them by default.
All common web browsers, Google Chrome, Mozilla Firefox, Microsoft Edge, can include and use the colour profile specified in Windows. Mozilla Firefox is closer to the ideal out-of-box experience required for colour profiles by default, while Chrome and Edge can have the same capability, but it is not active by default, for unknown reasons.
The required settings can be carefully applied in each application, following the guidelines below. Special care is required to modify only the required parameters.
While not obvious, web browsers, particularly on personal computers and laptops, are extremely complex programs that are poorly optimised out of the box to handle colour information well. While they operate decently in most circumstances, configuration is required for best results.
Mozilla Firefox
Type in the address bar about:config, then, after agreeing to the prompt regarding the risk of modifying settings, enter in the search bar that appears in the page section, the following keyword, gfx.color_management
Note that there are two settings that have to be flipped from the "false" value to "true", by clicking the double arrow button in the right side of the row, for the following parameters, gfx.color_management.force_srgb and gfx.color_management.native_srgb. A succesful modification changes the parameter name to be written in bold. There is no need to save the settings, they are immediately applied. You can close the tab and the settings will be always applied.
Google Chrome
Type in the address bar chrome://flags/, then, after agreeing to the prompt regarding the risk of modifying settings, enter in the search bar that appears in the page section, the following flag, Force color profile
Note that there are two settings that have to be flipped from the "default" value to "sRGB", by selecting the value in right side of the row.
Microsoft Edge
Type in the address bar chrome://flags/, then, after agreeing to the prompt regarding the risk of modifying settings, enter in the search bar that appears in the page section, the following flag, Force color profile
Note that there are two settings that have to be flipped from the "default" value to "sRGB", by selecting the value in right side of the row.