Blip Lesson #1 - colour profiles

A few contributors have asked why their images 'change' once they've been uploaded to Blipfoto - colours may become less vibrant, and there might be a slight difference in overall contrast (a bit like our Paul's socks).

So, for everyone's benefit, we thought we'd dedicate a Blipblog entry to explaining why this happens and what you can do to get the best results out of your images.

It's kind of impossible to explain this without getting into a bit of technical detail, but if you want to cut to the chase and just find out what to do, we've put the important bits in bold.

Chances are, your digital camera embeds something called a 'colour profile' in every image you take. In simple terms, a colour profile is just a little bit of information which tells your printer and computer screen how the image should look.

Colour profiles are important because, of every possible colour in the universe (and despite what the man at PC World told you), your printer and screen are only capable of accurately showing a fairly restricted number, and this varies screen-to-screen and printer-to-printer. The colour profile is used to adjust any colours which can't be accurately reproduced to the nearest one which can.

So what's the problem? Well, Blipfoto removes embedded colour profiles when you upload your images.

Bearing in mind what we've said above that probably sounds like complete insanity, but there is method in our madness. First off, a colour profile is only any use if a) the software you're using to view the image understands and knows what to do with the profile, and, b) your screen has been profiled and correctly calibrated.

Some web browsers (the software which everyone uses to view images on Blipfoto) do recognise all colour profiles, some only recognise certain profiles, some apply a colour profile 0f their choosing regardless of what's embedded in the image and some don't even know what a colour profile is. Add to the that the fact that 99.6%* of the world's computer screens are not calibrated and things get very messy.

As a general rule therefore, it's best not to embed colour profiles in images destined for the web because the results will, at best, be inconsistent and unpredictable.

So what should you do? Simple - either convert to sRGB before upload, or don't colour manage images destined for Blipfoto. This should mean that what you see in your photo editing software looks as near as dammit to what you'll see on Blipfoto.

Most compact digital cameras will automatically embed the sRGB colour profile in the images they produce. Removing this profile won't have a hugely detrimental effect on the image and you probably won't notice much difference when the profile is removed on upload (because sRGB is intended to be a 'lowest common denominator' or 'default' profile, with a restricted range of colours which most devices will be able to reproduce).

However, if you're using a digital SLR, you may be producing images which have the Adobe RGB colour profile embedded. That's a great profile to use if you plan to print or do anything else with your images, but if you upload one of these files to the site, you're going to notice a big difference (because Adobe RGB allows for a much wider and more intense range of colours).

Something we plan to look at in the not to distant future is a way for the system to automatically convert all uploaded images to sRGB. But, in the meantime, if you find things look 'different' once you've uploaded them, we'd recommend following the advice above.

If you're using Photoshop, it's quite simple to convert your colour profile to sRGB - once you've finished working on your image, go to the 'Edit' menu and select 'Convert to Profile'. Set the 'Destination Space' to 'sRGB IEC61966-2.1' and click 'OK'. Use 'Save as' in the 'File' menu to save your JPEG, making sure 'Embed Color Profile' is checked.

We hope that helps explains things, but if you have any questions or want to share any of your own colour profile experiences, leave a comment below.

* Did you know that 83.2% of statistics are made up on the spot?