sRGB

sRGB

I keep getting the colour profile of files I save wrong, and I’m hoping that if I write about it, even if it does nothing for anyone else, it’ll stop me cocking it up. So let’s begin with definitions.

In digital photography there are a number of different ‘colour spaces’ – the other one of note (especially for me) is Adobe RGB. And this is where the explanations get too complex for my taste. I suspect that Amateur Photographer’s resident lecturer, Professor Bob Newman has explained it, but that probably didn’t help me at all.

The long and the short of it is that the Adobe space includes more different colours, but that sRGB (for standard RGB) is the web default, and this site is optimised for it. There’s a non-linear element to the way it works, which is good for efficiency, but may not be ultimately accurate. The Adobe space is better for printing but sRGB is better for the web. All of this means that if you upload something that isn’t sRGB, when you look at it on Ephotozine, the colours will have changed.

The trouble is that your software doesn’t know what you plan to do with your files, unless you actually tell it. If you ‘Save for web’ you strip out the EXIF data, but if you ‘Save as’ you will need to make sure that you’re saving the right format. I often forget to look…

So for one thing, I’ve been practising saving files. And, half the time, resaving with the right profile selected.



Can you tell the difference? Can I? A few days ago, I realised that I’d forgotten to alter the colour space of my post, but by then I’d got a few votes and four User Awards, so it obviously isn’t absolutely critical. Not always, anyway. At other times, it seems to matter quite a lot, particularly – for some reason – with flesh tones. That may be my imagination, though.

There it sat in my mind, stewing. I watched a number of videos on YouTube, most of which were very much about which profile you need to use, and matching the profile to the device or paper that you will use to display the picture. And then I found a channel called Color Plaza TV, which introduced me to the ProPhoto RGB colour space, which is bigger than the Adobe RGB space.

The quietly-spoken chap on Color Plaza also reminded me that all the colour spaces work on the basis of a set of mathematical coordinates, one for each of the three colours to indicate its intensity. Every colour we see is a combination of the three colours, and so can be described by a set of three numbers. All the colour spaces use three numbers, from 1 to 255.

We’re used to seeing colour spaces as a two-dimensional graph, but spaces are actually three-dimensional things. Color Plaza used an infographic showing the spaces, and made the point that a physically larger space which is defined by the same 1-255 coordinates has a bigger difference between 1, 1, 255 and 1, 1, 254 than another (smaller) colour space. You may want to think about that a bit in order to process it from ‘of course it has’ to ‘so the same numbers give different colours in different spaces’ – I certainly had to!

And this is where the odd thing happened. I set my colour space on Photoshop to ProPhoto RGB to see what happened. I didn’t notice anything at first, and then I saved a colourful image as an sRGB file, and it became darker and duller. The two separate versions sitting side-by-side on my recent images view of PS are markedly different.

I’m writing this at five in the morning, because I woke up and wondered if by saving the file that way I had lost data. I had to get up and find out: so I opened the sRGB file, then altered its colour space to ProPhoto RGB. And the colours came back…

The importance of the profile isn’t in terms of absolute information, but knowing how it will look when you and others view it. If you are working in a bigger space and don’t look at (and save) your image as an sRGB it will look different when you post it on the web. All the data will, I think, still be there, but you won’t be able to see it in the way that you expected…

This is the heart of the advice to post in sRGB: it’s so that you can be sure that other people will see what you did. Please note that I am still at the start of a journey here! It may be one that you can make as easily as walking down the street, but I have struggled, and I have blisters inside my thinking boots. Any helpful thoughts will be gladly accepted.

But please don’t just say that you always shoot JPG files and they’re good enough for everyone the way they come out of the camera…