Color Management MythBuster — Facts & Myths About Color Spaces And Color Profiles

Author: Shivanand Sharma Published: September 1, 2011 0 comments

Color management is the essence of reproducing accurate color information. As much as it is required for attaining color consistency across devices more it gets complicated with each person preferring specific color profile and working space for color managed workflow. While we have taken this topic earlier as well for introducing color management, color spaces and working spaces, this post is dedicated towards various issues, queries, facts and myths about color management. Get started with your specific query.

1. Should I shoot in sRGB or Adobe RGB?

Majority of DSLRs provide the option for selecting either sRGB or Adobe RGB. The option only has effect on JPEG images, RAW format as such does not have a color profile (since RAW is not even an image, it’s pure data). Nikon’s specification on choosing the color space at the time of shooting thus recommends to:

Choose sRGB for photographs that will be printed or used as it is without any further modifications. This is to say that if you want to primarily use the images for viewing on-screen (on your computer and share over internet) you can safely opt for sRGB, the standard color space.
Choose Adobe RGB for images that will be extensively processed or retouched after leaving the camera. This means Adobe RGB should be preferred when you are preparing your photographs for prints because of the larger color gamut of Adobe RGB.

2. Which color space should I use for printing?

Depends on the gamut of your printer. If you are lazy, just let the printer manage your color profile settings/conversion. If you are using a commercial printer or sending the images to lab you may want to check with the lab. Most of the new inkjets can cover the Adobe RGB gamut. So if you have an image in Adobe RGB, by all means go for the Adobe RGB profile. But if your image itself is in sRGB, don’t bother with anything wider or bigger.

Working Spaces

3. Why are my prints dark?

This is the most common question posted on the photography forums. Most of the people complaint that the colors in the prints are darker than what they see on their screens. This depends on several factors:

Monitor Calibration And Soft Proofing Profile: The problem with monitors is that they can be set to any brightness or contrast level. So if you have set your monitor to be very bright you are not viewing the actual brightness of the image. Monitor calibration is thus the first step in the color management workflow. This is a crucial step in ensuring color consistency across the devices. With regard to monitor calibration, to preview the actual result you need to calibrate your monitor in accordance with the target settings. If your aim is to emulate the prints, you will need to set the white point (ideally D65 to start with) and luminance (in the range of 120-140 cd/m²) accordingly. Once you have calibrated the device in accordance with the target medium, soft-proof the printers profile to preview the print results.
Print Viewing Condition: If you view the final prints under varying light conditions, the results vary. If you view the prints in low ambient light, the prints are sure to appear dark whilst day light viewing. So it is important that you view the prints in the similar lighting as your printing workstation. If even then the results vary, it reflects that something has gone wrong with monitor calibration itself.
Missing Color Profile: When issuing the print command the color management was turned off. For true colors to be output, the color management must be enabled either in the software or the printer itself. Turning off color-management will also result in a color-shift.

Refer to the article why are my prints too dark by Andrew Rodney for a better insight and technical explanation of the problem.

4. Why is the color shifted?

The color shift simply means that the colors of the image are changed when viewed on various devices. This happens due to one of the following reasons:

No Color Profile Embedded: If you do not tag the color profile to the digital image it is sure to lack color consistency across the devices and thus a difference in color values when viewed on various output devices. Embedding the color profile to the image solves the problem. Using the color-aware / color-manged applications like Photoshop enables you to assign and embed the color profile to the images.
Ignoring The Color Profile: When you ignore the image’s embedded color profile, the color managed application assigns it the default profile resulting in clipping the color information lying outside the color gamut of the assigned profile, resulting in a color shift.

To ensure that there is no color shift, always use a color managed application and ensure that the application asks for your consent over ignoring, assigning / converting or embedding the required color profile. For instance you can specify the color management policies in Photoshop for missing profiles and profile mismatches to ensure that the color profiles are handled appropriately. By default Photoshop preserves the embedded profiles. Follow the given steps to verify the color management policies in Photoshop.

Go to Edit > Color Settings or press Shift+Ctrl+K to open color settings dialog.
Under Color Management Policies section, make sure that RGB, CMYK and Gray are set to Preserve Embedded Profiles.
Check the Profile Mismatches and Missing Profiles options (ask when opening and ask when pasting). This will ensure that when you open an image file, Photoshop will ask you to either ignore, assign (convert) or embed the color profile.

5. Why is ProPhoto RGB preferable working space for photographers?

ProPhoto RGB offers an especially large gamut designed for use with photographic output in mind. Even when the color gamut of ProPhoto RGB cannot be fully reproduced by any output device, it is recommended working space for photographers. The primary reason for choosing ProPhoto RGB as the working space is its ability to contain all the original colors captured by the camera in RAW format. Using a wider color space ensures that there is no color loss. With ProPhoto you can also retouch to exaggerate and artificially induce the ProPhoto RGB colors (but that requires a lot of expertise and there’s no reason why one would need to). However if your original image is anything smaller than the ProPhoto RGB gamut then don’t bother with ProPhoto.

6. Why use ProPhoto RGB when the monitor cannot display it and printers can’t print it?

Even when the color gamut of ProPhoto RGB cannot be reproduced on the output devices, ProPhoto RGB is preferable owing to two facts:

Preserve Color Information: Especially when shooting RAW, the camera sensor collects the color information which is practically out of color gamut of any working space. Using the working space with largest color gamut is clearly a winner in retaining and preserving the colors which are otherwise clipped and lost when you shoot in sRGB or Adobe RGB.
Effective Mapping Of Color Information: After assigning ProPhoto RGB as the working space you can easily convert the image to either sRGB or Adobe RGB. When converting the image from a wider working space to a smaller working space the color information is not clipped. In fact the colors are mapped to match with the destination color space and thus reproduce true and accurate colors within the limited color gamut.

Assigning ProPhoto RGB also comes in handy for maintaining a master copy of the image. With the advancement in technology we may sooner or later come across the devices with extended Adobe RGB capabilities and thus reproduce ProPhoto colors as well. It is however important to note that when working with larger color gamuts it is recommended to work with 16 bit color information or else you may run the risk of posterization or banding (which may also occur when you convert from smaller gamut to wider one).

7. Which is better — Adobe RGB or ProPhoto RGB?

Adobe RGB was designed with the intent of reproducing the true colors in print. This was achieved by extending the color capability of sRGB towards the cyan and green in three dimensional color model to come up with an RGB color space which fully contains CMYK model. Adobe RGB is as such preferable color space for printing for commercial purposes. Also with the advancement in printing technology and evolution of inkjet printers supporting 8 to 12 inks it is possible to output Adobe RGB color gamut in prints. This characteristic of Adobe RGB makes it a highly realizable color space as against ProPhoto which encompasses 100% real-life colors along with 13% imaginary colors (lying outside the range of visual primaries). Still then ProPhoto is widely used by the photographers to preserve the RAW color data captured by the camera sensor.

8. Why do Adobe RGB 1998, ProPhoto RGB (non-sRGB) photos look dull/unnatural on my monitor?

This simply happens because the application you are using for viewing the images is not color managed. This may happen in Photoshop as well if it is set to discard embedded profiles. If you really like to have a choice of profile when opening an image, turn on the Profile Mismatch and Missing Profile options “Ask when opening” and “Ask when pasting” to ensure that Photoshop prompts you to ignore, convert or use embedded color profile whenever you open the image (or assign the profile to the image with missing color profile).

9. Which one is a better option — Color space conversion or using sRGB?

We have been talking a lot about color space conversion in the preceding paragraphs. The question thus arises that when we have to ultimately convert the image into sRGB color space, is it not better to use sRGB throughout the workflow. If you shoot mainly for internet then sRGB is optimal. However if you want to print, you’ll get richer colors with ProPhoto RGB or Adobe RGB based workflow.

10. What’s the difference between Assigning Color Profiles and converting into color profiles.

Assigining color profiles to images is a “sin”. Unless you have an image with a missing profile or you are very sure of it’s color-profile only then should you assign it a profile. Incorrect assignment results in a color-shift.

Conversion between color-profiles is a process wherein a source color-profile is mapped into a target color-profile retaining as many colors as possible and thus maintain the color integrity. During the conversion the subtle color detail is preserved and mapped effectively to render true colors to the photograph.

11. Capture NX2: Working Space vs Color Mode

When working with Capture NX2, color management becomes much more confusing. Besides RGB color spaces, Nikon also offers the color modes to select from. Nikon offers five color modes namely Mode I, II, III, Ia and IIIa. These color modes should not be confused with working spaces. These color modes are simply variations in combinations of RGB primaries to reproduce rich greens, reds or magenta. As per the usage terms, Mode I is desirable for portraits and Mode III is designed to render vivid colors especially rich greens more suitable for landscapes. Still both the modes are output sRGB color gamut with slight difference in the saturation level of hues, while Mode II is true Adobe RGB.

The working spaces on the other hand define the color gamut you can use for retouching an image. If you use this gamut, you must save into a target profile that can contain this gamut.

12. I don’t need color management. I just use the standard monitor and printer.

If you use a standard monitor and a printer and you never take or send these images to anyone and you find the colors accurate and you have no interest in complicating things, just use sRGB (or ignore color management). Due to the number of conditions in the previous statement, it is rare that you have such an environment to absolutely warrant a workflow free of color-management.

13. If I set my working color space to ProPhoto RGB, my photos will have richer gamut/colors.

Working space defines the set of colors which can be utilized for post-processing the image. Also just converting to the ProPhoto RGB doesn’t make a difference since it will not expand the small gamut into a wider one. Working space is meant to retain colors in images which have a wider color gamut.

14. I use Adobe RAW/Lightroom and I get perfect colors from my NEF RAW files.

This is not true. Put another way, the colors may be to your liking but they are not technically accurate (the actual colors that existed in the scene). NEF is a propietary RAW format and RAW doesn’t have a color-profile. Only the camera (or Nikon Capture NX2) knows the color curve of which Adobe has no clue. Adobe created camera profiles for many of these cameras in it’s lab and distributes them via the updates to Adobe RAW. Nevertheless, the moment you underexpose or overexpose, the colors are gone for a toss and can only be accurately reproduced if you shoot TIFFs or JPEGs or if you use Capture NX 2.

15. Having images with the correct profile will make them show right on my monitor.

It depends on the software you using to view the image is color managed or not. Windows and Mac are not color managed. They rely on the color managed applications to render accurate colors.

16. Working in ProPhoto RGB is a waste as one can’t even see what colors they are affecting?

Working in ProPhoto RGB is not a waste of time. Other than the benefits it has, you can actually visualize the colors you are editing. Photoshop’s advanced color management settings allows you to desaturate the colors to visualize what’s getting affected. Note that this helps you only visualize what’s getting affected. It however doesn’t display the actual colors as the monitor you are using to view the image outputs sRGB color gamut or Adobe RGB at the most. Remember, ProPhoto RGB is not meant to help you see extreme colors, it’s meant to help you retain the widest color gamut possible in your images. You can then convert them down depending on the target media.

17. I need ProPhoto RGB!

You may or you may not. If you can’t tell the difference between the ProPhoto RGB, Adobe RGB and sRGB variants of a colorful photograph, you are better off sticking to sRGB.

18. What’s the ideal color-managed workflow?

Shoot RAW.
If using NEFs use Capture NX or View NX to convert the RAW data to images and use Color Mode II (which is Adobe RGB — the widest gamut you can extract from NEFs while retaining true colors). For other non-proprietary RAW formats, Adobe RAW works well and use ProPhoto RGB.
With either of these profiles use a color depth of 16bpp.
After you are done with post-processing, convert the images to the destination color-profile.
Finally you may want to convert them to 8 bits. The order is important as reducing to 8 bits before profile conversion will result in banding. (Read why this artifact occurs in our previous post on working space comparison sRGB vs Adobe RGB vs ProPhoto RGB.)

If you still have some unanswered queries about color management, feel free to add to the list.