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Colour Space?? Whats that?

Updated: May 23, 2020

The moment I got my first Digital SLR camera, I was very excited to start shooting with such advanced equipment. It took me a couple of days to get acquainted with the basic settings. I planned my first herping trip to Matheran, the day I felt I learnt the basics of operating my SLR. Matheran, a hill station near Mumbaihas a wide range of herpetofaunal species. We used to visit this place almost every week in search of Green Vine Snakes, Bamboo Pit Vipers, Deccan Banded Geckos, Cat snakes and many more exciting creatures! Just like in my previous trips, I spent the entire night at Matheran and shot some decent pictures of Green Vine snake and Cat Snake. While coming back I also had a sighting of a beautiful chameleon. I was really happy with the sightings and was eager to process my first set of images shot on my new camera. The moment I stepped in, I switched on my PC and posted those images on social media. It didn’t take even a moment for me to realise, photographs were looking just horrible!! They were nowhere close to the ones which I had just processed so pulled them back immediately. I decided to dig deeper and to find out the reason why this happened.

As I studied, I found out there is a factor that ruins our photographs and makes them look dull and ugly. It is known as the  'THE COLOUR SPACE'. 

I realised then that the phenomenon needs to be studied in detail and a countermeasure needs to be found . As I was sure many people also faced the same issue I decided to write an article on the same and that is how you are about to read about colour space today. 

Lets first understand what do we mean by the colour space or colour profile. (Colour space and colour profile are often used interchangeably) A colour profile, is a data file which contains information of 'specific set of colours'. Almost all devices that deal with colours – e.g.  cameras, printers, scanners - use specific colour spaces to produce or represent different colours. There are different colour profiles available depending on the device and medium used. Let’s understand this better with an example of a painting shown below.

When you only have 1 colour and a white canvas, your colour space is limited ONLY to that colour ONLY! Of course, you can have different tonal variations of that colour by making the colour dark or light (Luminance). That's what colour space is! 

In photography particularly, there are three colour spaces used frequently.

sRGB, AdobeRGB and ProPhoto RGB. Here, RGB stands for

In photography particularly, there are three colour spaces used most frequently.

sRGB, Adobe RGB and ProPhoto RGB. Here, RGB stands for RED GREEN and BLUE. Absence of RGB is PURE BLACK whereas 100% (255) of each of these RGB is pure WHITE!

By adding or removing amounts of White and Black we are changing the luminosity that is the brightest of the colour!

Whichever colour we see can be represented by the combination of these three colours in appropriate quantity. That's how we get a numeric code of any colour. The top most colour is (255 Reds, 222 Greens and 0 Blues) Middle one is (0 Reds, 240 Greens and 255 Blues) Colour at the bottom is (80 Reds, 133 Greens and 57 Blues).  That’s how each and every colour has its own fixed numeric coordinates.

Now that the colour profile part is clear, let's discuss the particular colour spaces related to photography. The picture below represents the gamut of colours that the human eye can see. Anything outside this gamut is an imaginary colour. (A gamut is the range of colours that a colour system can display or print.)

Now the question is, how do sRGB, Adobe RGB, and ProPhoto RGB fit into this? sRGB, Adobe RGB intersect with the gamut of visible colours and in the case of ProPhoto, it stretches beyond the gamut of visible colours.

In the case of ProPhoto RGB, you can see, colour space stretches beyond the gamut at some point. That simply means ProPhoto contains some of the colours that we can NOT see. These are the imaginary colours.

As the diagram shows, sRGB is the smallest colour space, with a gamut only covering a portion of which colours our eyes can see. The Adobe RGB gamut is larger, and represents more saturated Green, Cyan and Blue colour. ProPhoto is the largest colour space. Please note in all these images we are not considering the Luminance (brightness) of the colour which results in darker or brighter colours. 

Now I am sure some of you must be thinking what am I supposed to do with this technical information?? I am coming to the point now! Each colour in the colour space can be represented by coordinates. A colour will have its fixed coordinates in thegiven colour space. As we discussed earlier, we can represent pure white as values (255,255,255) and pure black as (0,0,0) and similarly all the other colours. These coordinates will remain the same for a specific  colour in a given colour space. This basically helps us reproduce or map that colour with coordinates anytime. BUT, these coordinates are colour space specific. The same values will not represent the same colour in sRGB, Adobe RGB, and ProPhoto RGB.

See the example above, RGB values “202, 157, 49” represent different colours in ProPhoto RGB, Adobe RGB and in sRGB and that's the only reason why you may see some colours getting clipped off if the colour spaces are mismatching. Adding to the complexity of the issue is the fact that, most of the web browsers DO NOT read and represent Adobe RGB and ProPhoto RGB colour space. They support only sRGB colour space. This is why we need to convert the colour space of your images before posting on social media. 

How to do that? There are different options to convert the colour profiles while exporting the file, I will show the easiest one as of now. Once you are done processing your image just click on Edit > Convert to Profile and a new window will open. (Check the next picture.)

Select the colour space you want your images to be converted in. (For web, sRGB )

Follow this simple one step process in order to avoid clipping off colours of your hard-earned images. So, while processing your images, work with the bigger colour spaces in order to have better control over processing and finally when it comes to exporting, save them in sRGB to avoid clipping off colours while sharing on the Web. Before signing off, I would love to answer one of the recently asked questions, "Does bigger colour spaces have more number of colours"?? The answer is NO!! Although ProPhoto RGB is bigger in terms of range than sRGB, it does not contain more number of colours. An 8 bit/channel image will always have 16.7 million RGB combinations, no matter what the colour space is. In ProPhoto RGB these values are simply spread out farther leading to a problem known as “banding”. I will cover this important phenomenon of difference between 8 bit and 16 bit images, In the meantime, please feel free to ping me if you have any queries or suggestions.  Photography is fun!  Connect with me on Instagram at Saleel Gharpure

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