Once you start working with images you will quickly encounter different options for working color spaces. These spaces are responsible for a range of tone and color the image produces. The larger the space the more of a range the image can potentially portray. I am being asked quite frequently “what color space should be used” and “why not just use the biggest”? The answer to this question is not as straightforward as one might hope it would be, and it largely depends on photographer’s preferences, workflow and mode of image distribution.
There are three most common color spaces: sRGB, Adobe RGB and ProPhoto RGB. Each has a different range of tones, brightness and colors it is capable of operating with and each is used for different applications.
sRGB (aka sRGB IEC61966-2.1) – is a color space produced by HP and Microsoft in the late 90s. Since this color space was backed up by industry leading giants it quickly became popular with all image driven mediums such as cameras, monitors, scanners and printers. sRGB has the smallest range of tones and colors (about 35% of the full International Commission on Illumination (CIE) range) out of the three most popular color spaces, but it is the most versatile and widely used. It is supported by all cameras, screens and image viewing software, so if you just want to keep things simple and avoid color shift problems during editing or sharing, your best bet would be to shoot and edit files in this color space.
Adobe RGB (1998) – as you can probably tell by its name, this color space was created by Adobe in late 90s for suitable implementation of full color management in their Photoshop software. Because of wide use of Photoshop this color space quickly became popular and extensively supported. This is a wider color space, which encompasses around 50% of all visible colors (as defined by CIE), it is a good choice for editing in 8-bit or 16-bit modes and typically carries more information for print. However, there are some complications associated with using this color space that you should be aware of.
First of all, Adobe RGB is not supported by all browsers. If you intend to place your images online it is most likely that people viewing your images will see them in slightly different colors if the file is in Adobe RGB color space.
Secondly, Adobe RGB compresses colors and only special image viewing software’s can expand it back to reproduce all the colors in full gamut, all of the rest of the programs do not support this color space and will make the image look dull. So when you share your images, remember to convert them to sRGB. This creates an additional step in your workflow.
Finally, if you send your images to a print lab, most of them work with sRGB color spaces (unless they specifically mention a different color space) which will mean your prints would have incorrect (dull) colors, if printed with Adobe RGB profile.
ProPhoto RGB – was created by Kodak for advanced image reproduction on print. This color space covers the largest range of colors and even goes beyond of what our eyes can see. To achieve this range you must shoot in RAW format and open your digital negative with ProPhoto RGB color space in 16-bit mode. If you start editing in 8-bit mode you will most likely run into banding or posterization problems because with only 256 levels per color channel in 8-bit mode gradient steps are larger. Additionally you will not be able to save the file as JPEG because it only supports 8-bit mode. You will have to store the file in a format that supports 16-bit such as PSD or TIFF, and your printer will have to support this format. Therefore this color space is only recommended for photographers who have a very specific workflow and who print on specific high-end inkjet printers which can take advantage of such a high range of colors.
So which color space should I use?
As I have mentioned before, it all depends on your preferences and character. If you are planning on sharing your photos online, printing them at conventional mini labs or providing them to clients who have no idea what a color space is, then your best choice is sRGB. This is the most versatile color space and the use if it eliminates any hassle of converting and having extra steps in your workflow, giving you more time to actually shoot more images and focus on your creativity. Remember that most color problems occur when you start messing with color spaces other than sRGB
On the other hand, if you are the kind of person who likes to control every aspect of your workflow and print your images at home on advanced inkjet printer, then you should consider using Adobe RGB color profile. Additionally, sometimes specific clients, especially in publishing business, will explicitly ask you to provide images in Adobe RGB color space, because theoretically it has a wider color range. In that case you would want to use Adobe RGB and carefully monitor each of the transfer steps in your workflow.
Finally, if you are a complete perfectionist who prints on high-end inkjet printers and wants to make use of the entire color range visible to human eye and even some imaginary color (yes, there are imaginary colors employed by this color space) then you should go for ProPhoto RGB. This will, however, force you to use very specific steps in your workflow, such as shooting RAW (ProPhoto RGB is native space for Camera RAW) and only using 16-bit files.
Assigning color space in camera
Most modern digital camera support sRGB and Adobe RGB color spaces. You can usually specify which color space you want your camera to use when saving JPEG files on a memory card. To choose it go to menu and look for color space option. Please refer to the user’s manual for your specific camera instruction.
Assigning color space in Camera RAW
If you shoot in RAW, then you can choose a specific color space when opening a file in RAW software. In Camera RAW, which comes standard with Adobe Photoshop, you can do this by clicking on bottom link in the middle of a window and selecting a color space from a Space drop down box. Remember to also select 16bit/Channel depth if you are choosing ProPhoto RGB or even Adobe RGB color space.
Setting up Photoshop color setting
When working in Adobe Photoshop also remember to select appropriate color settings. You can do this by going to Edit>Color Setting on the top Navigation Panel. Once there, select RGB working space and make sure to check boxes that will prompt you if there is a profile mismatch to avoid any inconsistencies.
Switching between color spaces
Sometimes you might want to switch between different color spaces. This can be done with several editing programs. Remember that you don’t want to just assign a new color space, but want to convert to it using advanced algorithm in order to correctly preserve all the colors. I will use Adobe Photoshop as an example. To convert color space, go to Edit>Convert to Profile on the top Navigation Panel. New window will show you your current color space and give you an option to select which profile you would like to convert to. This conversion can be done through four different methods (Perceptual, Saturation, Relative Colorimetric, and Absolute Colorimetric). If the description of these methods below seem overwhelming just know that you are better off just using Relative Colorimetric conversion method for your photos.
Perceptual mostly focuses on keeping good correlation between out-of-gamut colors, but it may negatively affect the relationship of in-gamut colors. This is sometimes effective when converting to CMYK color space.
Saturation, as the name implies, is focusing on maintaining good saturation of colors. It is usually used when converting to wider color space. But it is typically not recommended for digital photography, because it doesn’t preserve realistic colors.
Relative Colorimetric focuses on accurately producing in-gamut colors, but it sometimes sacrifices out-of-gamut colors. This is the best rendering option for photos and is most used for screen and print.
Absolut Colorimetric is typically used for proofing. It tries to reproduce all original colors, but does not take into consideration for the illuminant or light source. This usually causes wide color shifts when viewed under different lighting. Therefore, this method is not recommended for photography.
Additionally you can use color proofing to see how the image might look like on different mediums. Remember, however, you monitor should be properly calibrated to present colors close to real results. To set color proofing in Adobe Photoshop go to View>Proof Setup on the top Navigation Panel and select which ever medium you would want to see it in. Make sure Proof Colors is active at View>Proof Colors to see results.
Personally, I use sRGB colors space exclusively for all my projects. This allows me to share, post and sell images without ever thinking about end user seeing noticeable color shifts; unless their monitor colors and gamma are way off by default, but in that case they see all images like that and are probably used to it. I know many of my collogues use Adobe RGB to maintain larger range of gamut but I keep on hearing all kind of stories from them how that gets them into problems. And honestly I can’t see such a quality difference between a print from sRGB and a print from Adobe RGB to justify to myself to go through all the hoops.