Notice how larger colour spaces like Adobe RGB and ProPhoto RGB have a triangle covering a larger area. This shows they can reproduce a wider range or gamut of colours than a small Color Space like sRGB.
Out of Gamut Colours
When we reproduce an image as a print or on screen, there is also a limit to the colours that device can produce. If you look at the illustration above, you can see the outline of a Color Space for “2200 Matt Paper”. Notice that it doesn’t even cover the sRGB Color Space meaning it can’t reproduce all the colours in sRGB.
When we have a colour that falls outside what something can produce, it’s said to be “Out of Gamut”.
When a colour is out of gamut for a device, the device can’t just ignore it. It still needs to display something. It overcomes this problem by replacing the colour with the closest match that it can display. When there aren’t many Out of Gamut colours in an image you may not notice the change. But if there are a lot, it can cause a colour shifts in an image.
Which Color Space to Use
Now we have discussed Color Spaces you may be wondering how to use this information.
When it comes to editing photography, you should try to use a large Color Space like Adobe RGB or ProPhoto RGB. Using a wide range of colours can help prevent the loss of subtle detail which may rely on faint transitions between colours. It can also help prevent unwanted colour shift and keep photographs appearing natural.
But when we come to share an image with someone else, we must assume their device can only display a small Color Space like sRGB. That’s why sRGB is the “standard” used for the internet. It’s a small Color Space and most modern devices can handle all its colours.
Most editing software has a way for you to convert the Color Space of an image. Let’s look at a few common examples.
Converting to sRGB in Affinity Photo
Open the image you want to convert to sRGB in Affinity Photo.
From the Photo Persona menu select “Document” then “Convert Format/ICC Profile…” This opens the Convert dialog.
Here you can see the current Color Profile used by your document highlighted in the list. In the above example, this is ProPhoto RGB. Scroll through this list until you find the sRGB profile, then click to select it.
Click the Convert button to convert the photo into sRGB.
Converting to sRGB in Adobe Photoshop
Open the image you want to check in Adobe Photoshop.
In the Photoshop menu select “Edit” and then “Convert to Profile…” This opens the “Convert to Profile” dialog.
At the top of the dialog you will see the “Source Space”. This is the current Color Space of your image which in this example is Adobe RGB (1998).
To convert to the sRGB Color Space, select sRGB from the “Destination Space” drop-down.
Click the OK button and the document will convert to sRGB.
Converting to sRGB in Lightroom
When you’re editing a photo in Lightroom you can’t see or control the Color Space. Lightroom forces you to use ProPhoto RGB, which is the largest Color Space. But when you export the image to a file you can choose the Color Space of the image in the Export dialog.
To export an image using sRGB, first select the image from your Lightroom Catalog.
Now select File from the menu and then Export. This displays the Export dialog.
In the Export dialog you find a section called file settings. Here there is a drop-down to select the Color Space to use for the export.
Change this to sRGB before clicking the Export button.
Now you understand how to handle images for display, let’s cover printing which is where we need the ICC Color Profile.
Color Spaces When Printing
The problem of Out of Gamut colours can happen when you’re printing. Photo papers and printers also have a restricted gamut or range of colours they can reproduce. You can even think of it as being just another colour space. The printer also handles out of gamut colours in the same way as a screen. It will replace them with the nearest colour it can produce. As with the screen, this can lead to shifts in the image colours which could mean your print doesn’t match your screen.
The problem then is how to identify which colours your printer and paper combination can reproduce and if there are Out of Gamut colours. The solution to this problem lies with the ICC Color Profile.
Using ICC Color Profiles in Printing
We can use an ICC Color Profile to simulate how one device sees colours using a different device. The ICC Profile allows us to translate the colours between devices, so they match. In printing, this process is known as Soft Proofing. Soft Proofing allows us to see a representation on our screen of how a physical print will appear before we print it. We can then check for Out of Gamut colours to see if they are causing a colour shift.
If we find a problem, we can correct it by applying further adjustments to the image so that it matches (as closely as possible the original finished image). These are proofing adjustments which you only apply to the image you print. This means you need to work on a copy image which we sometimes call a proof copy. It’s not uncommon for the proof copy to look dreadful on the screen when it’s not being soft proofed.
You can learn more about how to Soft Proof an image in Lightroom with my tutorial.
There’s a different approach if you use:
- Capture One for printing, or
- Affinity Photo, or
- DxO PhotoLab
Which ICC Profile to Use
Now back to the question of which ICC Profile you should use.
There are two elements to producing a print, the paper, and the printer. It’s the combination of the two that determines the range of colours (or gamut) in the print. Change either the paper or the printer and you change the colour range.
One common mistake a lot of people make when printing is, they decide they don’t like the soft proof. They then change to a different ICC Profile because they think that looks better. What they should be doing is adjusting the proof copy to make it match they original image.
When you select an ICC Profile for a different paper and/or printer combination to the one you are using, your soft proof won’t be accurate. Your software is simulating a completely different combination or paper and printer. But the problem is worse than this because your printer also uses the ICC Profile when it prints.
Printers Use ICC Profiles
When you print an image, you have two options as to how your printer manages colours:
- You can allow the printer to manage the colours. The printer then does it’s best to reproduce accurate colours. But because it doesn’t know which paper you are using it can’t make any adjustments to the colour. You could experience colour and tone shifts depending on the image and paper used.
- The software you print with can use the ICC Profile to manage and accurate reproduce the image. The ICC Profile gives the printer the information it needs to accurately represent the colours and tones in the image. This approach also requires the printer doesn’t try to do any of the colour management.
The most accurate option of the two is for printing to use the ICC Profile.
Now image you haven’t used the correct ICC Profile for your paper and printer combination. You’re giving the software a set of instructions on how to reproduce colours and tones except they are the wrong instructions.
The only ICC Profile you should use is the one that matches your paper and printer combination.
If the paper you use doesn’t have an ICC Profile for your printer, switch to a different paper that does. The only other alternative is to have a bespoke profile created.
