sRGB or bigger?

Some software, such as Photoshop allows you to choose your device-independent colour space: the colour space witihin which you will do your editing.

You may read or hear that if you have a choice you should "always use sRGB".

This is poor advice in respect of your working space.

colourspaceworkflowThe picture represents (not to scale) the relative 'sizes' or gamuts, of the colour spaces that must be connected and translated between in a colour-mananged workflow.

The gamut of sRGB is roughly the same 'size' as that of the monitor.

The gamut of a good printer is closer to Adobe RGB.

But the colour gamut of the camera's RAW colour space is greater than either sRGB or Adobe RGB.

The device-independent working colour space is the 'esperanto' used in connecting correct colours between the devices. It is also your working or editing space.

If you convert from your camera's colour space to Adobe RGB or sRGB, you must throw away colours that are outside the gamuts of those spaces. Whereas if you convert to the ProPhoto RGB colour space you will retain all colours that the camera captured.

In his book Color Management for Photograhers, Andrew Rodney argues that the ideal working space is one that can fully contain the entire gamut for printing. That makes sense.

Other people argue that because you cannot see on your monitor the colours that are beyond its gamut you might as well throw them away and work only with sRGB. Then you can see everything you're working with and everything that will be printed. That is true, but ...

  • some of the colours you captured (particularly saturated blues) could have been printed if you hadn't thrown them away;
  • more data is usually better:
    • as you edit you may make adjustments to saturated colours that may well have brought them into the gamut of your monitor or printer had you retained them all.
    • once you've thrown colour data away there's no way to get it back;
  • technology is always improving. Down the track its very likely that both monitor and printer colour spaces will be bigger than they are today. If you convert your images to ProPhoto RGB, and save them with that colour space embedded they will be "future-proofed".

Go big!


The exception

There are a couple of circumstances where it is necessary — even sensible — to convert an image's colour information to the sRGB colour space. For example, if

  • you are exporting a file to be displayed on the web, or
  • you are sending an image to someone who will view it on their monitor or digital projector,

you should probably convert the image to sRGB. Why? Because files on the web are going to be viewed via web browsers on monitors you know nothing about. It is very likely that the monitor used to view your image will not have been properly profiled and it will probably have a narrow gamut, no bigger than sRGB. Images encoded in large colour gamuts that are viewed in such circumstances almost always look oversaturated and awful! Encoding in sRGB, which is the lowest common denominator of colour spaces, is prudent in that case.

... back ...