sRGB vs. Adobe RGB vs. ProPhoto RGB

Once you start working with images you will quickly encounter different options for working colour spaces. These spaces are responsible for a range of tone and colour the image produces. The larger the space the more of a range the image can potentially portray. Then, “what colour 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.

WHAT IS COLOUR SPACE..?

colorspace

In layman’s terms, colour space is just a specific range of colours that can be represented above. JPEG images can contain up to 16.7 million colours, though neither colour space actually uses all 16.7 million colours available. Different colour spaces allows for you to use a broader or narrower range of those 16.7 million colours used in a JPEG image. The difference lies within what is considered wider and narrower colour spaces.

TYPES OF COLOUR SPACES:

There are three most common colour spaces: sRGB, Adobe RGB & ProPhoto RGB. Each has a different range of tones, brightness and colours it is capable of operating with and each is used for different applications.

sRGB (IEC 61966-2.1) is a colour space produced by HP and Microsoft in the late 90s. Since this colour 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 colours (about 35% of the full International Commission on Illumination (CIE) range) out of the three most popular colour 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 colour shift problems during editing or sharing, your best bet would be to shoot and edit files in this colour space.

chromaticity_diagram

Adobe RGB (1998) – as you can probably tell by its name, this colour space was created by Adobe in late 90s for suitable implementation of full colour management in their Photoshop software. Because of wide use of Photoshop, this colour space quickly became popular and extensively supported. This is a wider colour space, which encompasses around 50% of all visible colours (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 colour 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 colours if the file is in Adobe RGB colour space.

Secondly, Adobe RGB compresses colours and only special image viewing software’s can expand it back to reproduce all the colours in full gamut, all of the rest of the programs do not support this colour 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 colour spaces (unless they specifically mention a different colour space) which will mean your prints would have incorrect (dull) colours, if printed with Adobe RGB profile.

ProPhoto RGB – was created by Kodak for advanced image reproduction on print. This colour space covers the largest range of colours 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 colour 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 colour 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 colour 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 colours.

EFFECTS OF COLOUR SPACE:

The image below explains it pretty well. Both images contain only three colours, however, the colours shown in the Adobe RGB scale have more differential between them. This means photos taken in the Adobe RGB colour space will have more vibrancy in their colours, whereas sRGB will traditionally have more subtle tones. In situations, where you’re photographing strong colour tones, sRGB may need to dull them out to accommodate, whereas Adobe RGB is able to display those colours with more accuracy.

colorrangessrgbadobergb

Does all of this really make a difference? Let’s take a look at some images that were shot in RAW (thus no colour space recorded on capture) and then saved as both Adobe RGB and sRGB using Adobe Photoshop Lightroom.

srgb-1-500x333
sRGB
argb-1-500x333
AdobeRGB
srgb-2-500x333
sRGB
argb-2-500x333
AdobeRGB

In all of these cases, the images saved as sRGB should appear more vibrant in Internet Explorer and Firefox since they are not colour managed applications. Apple’s Safari browser is supposed to properly display Adobe RGB files and Chrome/Firefox is supposed to have colour management in upcoming versions. However, until everyone is using a browser you should avoid Adobe RGB in order to provide the best images to the widest audience.

proscons

WHAT ABOUT PROPHOTO..?

ProPhoto offers the widest gamut of the available common colour spaces so should have a place somewhere right? Well yes it does. The best use of the ProPhoto is to use it within your workflow to preserve the largest amount of colour in your images and then only do a final conversion to sRGB when saving your images as JPEGs. This is quite easy with Photoshop and Camera Raw while Lightroom uses ProPhoto RGB internally

(Geek Note: Actually, Lightroom uses Melissa RGB which uses ProPhoto RGB chromaticity values working in linear gamma, named after Melissa Gaul, one of the Lightroom Engineers).

SELECTION OF COLOUR SPACE:

Now that we’ve put it into perspective, here are the most common questions photographers have:

  1. Do I shoot in Adobe RGB or sRGB?
  2. Around which colour space should I build my workflow?
  3. For web publishing, which colour space should I use?
  4. For prints, which colour space should I use?

The answers to these questions depend largely on your preferences. You must remember that there are disadvantages to each colour space, which is the primary reason why photographers are divided in their opinions about the ideal colour space.

Do I shoot in Adobe RGB or sRGB?

Before you read the answer to this question, ask yourself if you shoot in RAW or JPEG.

If you shoot RAW, ProPhoto RGB is already the native colour space and you don’t need to make any changes to that. You’re already recording the maximum range of colours.

If you shoot JPEG, knowing that Adobe RGB has a wider range and the applications you use to manage and process your image can handle Adobe RGB, you’ll do well to stick with Adobe RGB. Unless of course, you don’t want to add extra steps to your workflow (for sRGB conversions).

Around which colour space should I build my workflow?

Until you get to the step where you’re looking to publish images or print them, your workflow largely involves moving the image between applications, processing it, or storing it. So, clearly ProPhoto RGB is the colour space that gives you the widest range along with a 16-bit choice, you’ll have the maximum number of colours to play with.

1) Lightroom workflows already use ProPhoto RGB.

2) In Photoshop, go to Edit -> Colour Settings. Under “Working Spaces”, select “ProPhoto RGB” in the “RGB” drop-down menu. Also, check the settings “Ask When Opening” and “Ask When Pasting” under “Profile Mismatches” and “Missing Profiles”.

photoshop-settings

For other applications and plugins like Nik or Topaz, figure out how to set the colour space to ProPhoto RGB and incorporate this as part of your workflow.

The reason you’d want to use ProPhoto RGB is that there’s a lot of data that can give you the extra leverage while editing. Plus, with future advancements, you’ll be closer to transitioning to the newer, better colour space than with either Adobe RGB or sRGB.

Of course, whenever you want to print or publish on web, you can always convert the image to the colour space of your choice.

For web publishing, which colour space should I use?

For the sake of simplicity and assurance that your colours will be represented accurately, sRGB is a safe choice. Most applications and display devices use sRGB, and you can be sure that you will not encounter nasty surprises.

Of course, several high-end devices have begun adopting the Adobe RGB colour space. But, that again is a minority. For images that look great on the Web, sRGB is the way to go.

You must also remember that you can start with Adobe RGB and convert to sRGB, and the missing colours will be compensated—with a loss in vibrancy. sRGB conversions usually give you muted, subtle colours, but you will be hard-pressed to tell the difference in the vast majority of display devices we use.

But converting sRGB to Adobe RGB will not give you efficient results, and the remapping of colours can prove disastrous, even if that’s an exaggeration.

For prints, which colour space should I use?

The safest approach is to check with your printer guy. Some of them use Adobe RGB today. So, if you want vibrant colours and a better range, and your printer supports Adobe RGB, your choice should be simple. Besides, the consistency in colours will be far better than on your monitor (that uses sRGB).

Also, if your printer doesn’t use Adobe RGB, you might see a different set of colours than you originally envisioned. Know your colour spaces well, and you’ll always end up with colours that are as close to the original capture as practically possible.

SUMMARY:

The most efficient workflow makes the best use of all worlds. Shooting in RAW gives you the widest colour range with ProPhoto RGB and convert to the colour space you want during your workflow process. If you want to shoot in JPEG then you have to make the choice.

For Web publishing, sRGB is the safest choice. For prints, Adobe RGB will give you the best results if your printer has adopted the Adobe RGB colour space; if not, stick with sRGB.

The best thing to do is actually experiment with your equipment and software to determine what gives you the best results. In the end, you have to make up your own mind as to what works best for you, but you do need to be aware of the differences and some of the issues you can run into based on your choice.

 

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