Colour Management for Photographers 2

This is the second instalment of a series on colour management. The index of the sections is shown below, and the links to all completed section are active.

Section One – Why Colour Manage
- Part One – In the context of the world we live in
- Part Two – Why is our workflow important? (below)

Section Two – All About Colour Spaces (coming soon)
Section Three - Capture, Display and Working Management (coming soon)

Section Four – Output Management (coming soon)

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Section One – Why Colour Manage? Contd…

Part Two – Why is our workflow important?

So from the first part of this section, we should now roughly see why it is necessary to colour manage at all. This second part will discuss why it is necessary to include colour management in our photography workflow. In an ideal world, once we have taken care of the lighting and colour of our subjects at the shoot, our concerns over colour accuracy would stop there. Unfortunately reality is far from that ideal, and we need to discuss a little bit why there is a need to colour manage through each step of our workflow.

I really want to keep these articles down to a bare minimum of information, and it is quite tricky to do so, as the subject is huge and complex. I think it is important to include enough information to really understand what is going on with colour management rather than just having people repeat parrot fashion and not really understand why it is they are doing it. This limits your ability to adapt when and if things go wrong and decreases your confidence of using it. The simplest way I can think of to demonstrate why our workflow needs colour management is to use an example of where things can go wrong if it is not used.

A Prime Example of Lacking Colour Management

Our example is going to take a person that either is not aware of colour management or decides not to use it. This person has recently gone out and bought a top-of-the-range dSLR and all singing and dancing photo inkjet printer. Obviously being quite interested in photography they choose to shoot RAW and import their RAW images into a raw converter. The first thing they decide to do is set white balance (a good place to start). Along with probably the majority of people, they set their colour balance by eye-balling the image. They adjust the sliders around to get the colour in the shot to look pretty damn close to how they remember the scene looking. Happy that the WB is set correctly they move on to completing their edits, maybe a little playing with saturation, setting the overall exposure and the black& white points. At this point they have the image spot on and are ready to get there super new printer to spit out a nice 18” print. The printer does it stuff and they go to make a cup of tea. A few moments later they come back and the print is finished, so they pull it off and hold it up to the light. They then stagger two paces backwards as the printer has products the most disgusting distortion of colour and shades possible. Everyone in the photo looks like they have applied copious amounts of Duotan and the sky is green. Their first and natural reaction is to be rather disappointed with the printer they just shelled out so much money for. In fact I read that the majority of complaints that printer manufacturers receive is from just such cases.

The fact that they blame the printer is understandable, their logic being that the state of the art camera surely is doing its job – they have seen wonderful images from other people with that exact same camera - so they assume the issue must lie with the printer. A certain degree of the problem may lie with the printer – but in most cases it isn’t the printer at issue. All through the process they assumed their monitor was showing them the correct colour.

Now let’s adapt the situation slightly. Say they shot the same image in JPG in the camera. They did not touch the photo in any software, just sent it to print. In all likelihood the image would print pretty well, certainly a lot better. Hmmm.

The facts here are that by and large the camera manufacturers turn out pretty accurate capturing devices, so they record the scene pretty well. In turn the printer manufacturers, certainly in the case of printers marketed for photo printing, turn out fair accuracy on their printers. The result is sending one directly to the other results in a pretty close colour match. What most people fail to consider is that when they view the image from the camera on their screen they are seeing the original file how the screen decides to show it. Most people do not go and buy “photo” monitors – for one thing they are expensive and seem unnecessary (usually they are unnecessary), they are quite happy with their screens and don’t give it much thought. A big mistake. Monitor manufactures are not really in the limelight when it comes to colour accuracy. That is because most people don’t really care that much, as long as it is in the right ball park you are good to go. You probably should expect reasonable accuracy though, and *may* even have it, but way back when you first got your monitor maybe you forgot that you played a little with the controls to get the brightness etc. Just how you like it…. The result being that the image may have been spot on in the first place, it just looked rubbish on your screen, so you adjust it to look right on your screen; in turn make the actual file rubbish!

Of course there are many many reasons why a monitor may fail to show good colour accuracy. Up till now we have only spoken of monitors, but the fact is that to lesser or greater degrees all devices will suffer some inconsistencies that effect accuracy. You might be sitting there saying, “Well I paid a lot of money for my monitor, and I never touched the controls, so it should still be spot on”. Well you can think that if you like, but look through some examples below of why any device may cause colour inconsistencies and inaccuracies.

Manufacturing Process

Every device you buy is mostly likely a combination of many components coming from various manufacturers. Perfection in electrical components is neither achievable nor practical. Therefore components have a tolerance value, a level in inaccuracy they are permitted to fall within in order to be deemed acceptable. So even if your buddy down the road has the exact same monitor, and all the controls are set exactly the same as yours, it is likely that the colour it displays is slightly different. There is of course even more disparity if he owns a different model, and even more of from a different manufacturer. If they are using different components, and maybe even different technologies you are really expecting a lot for them to produce nearly identical results. Of course, I keep using monitors as an example (as it is the most common error, and also the easiest to fix – as we shall see in future instalments), but the same applies, and probably in many cases even more, to all devices.

Natural Degradation

As with all things, devices age, and with that aging process changes to their output occurs. So even if your device was truly accurate a year ago, the likelihood is that the components responsible for the imaging are now producing different results. This fact is true even once you take on boards colour management techniques, and requires that you continually carry out steps to remain in a good colour managed workflow.

fig.2 - Although getting ahead of the game a bit, and in the next instalment we shall talk more about colour spaces, this shows the gamut (available colour palette) on the Epson 1290 inkjet printer (custom profile by nimby) as the solid shaded area. This is a 3D representation, and you are seeing only one side here (magentas and yellows). The concept is that the 1290 can produce all the colours that are inside this shaded area, but cannot produce any colours outside the shaded area. The dots sprinkled around are a representation of all the colours that make up the photo at the top of this page. As you can clearly see a large number of these dots (colours) fall outside the shaded area (gamut) of the 1290 printer. That is to say that the 1290 printer CANNOT print those colours....(graphic copyright of nimby)

Inability

Up till now we have just assumed that our device is actually capable of producing the required colour. Actually in reality this is a long way from the truth and is a huge reason for the need to colour manage. In the next instalment we shall discuss this in more depth, but for now it can just be said that NO monitor can produce all the shades and tonalities that a camera can capture, and neither can any printer. Further, NO device can fully encompass the human eye’s range of colour. Fig.2, above, demonstrates a prime example where a device's colour capabilities prevent it from reproducing the true colours as they were in the scene.

Methods of Visibility

This is a tricky subject. It is huge and complex, but I will attempt to summarise it in quite a few sentences. It can be said that the human eye receives colour from two methods of source. The first is transmitted light, a good example of that is the monitor you are looking at now. It is its own light source, and that is why you can see it in a dark room! The method by which you see colour from your monitor is that the monitor transmits light to your eye in colours that your eye is sensitive to, as shown in fig.3, below. To give a simple example to demonstrate, let’s say you have a photo of a pure green apple, lit with white light on your screen. Your screen will transmit green light and the eye, being sensitive to green (along with red and blue) sees the apple as green. All good.

fig.3 - A graphical representation showing the concept of transmitted (a.k.a emitted) light's ability to give colour. A simple real life example would be red, green and blue coloured glass. When white light (a mixture of red, green and blue light) is shone through the coloured glass only parts of the spectrum pass through, the others are absorbed. In the case of red, as shown above, the green and blue parts of the spectrum are absorbed, leaving only red passing through - so we see the colour of the glass as red. Naturally, if we were to mix red and blue to make a magenta coloured glass, this would allow both red and blue to pass through, giving a magenta light (this is adding colour - an additive process). If we mix all three, red, green and blue to make the glass, it would allow all of the light to pass through and we would see white. (graphic copyright of nimby)

There is however another method of visibility and that is reflected light, see fig.4, below. Anything which is not its own light source relies on reflected light for you to see it. (There are of course overlaps, but let’s keep it simple.) Let us take that same green apple as it would have been before we photographed it. It was sitting on a table being lit with white light. It does not produce its own light therefore it must reflect some of the light being shone on it for you to see it. The reason it appears green to the eye is that it does not reflect all of the white light shining on it. In this case it absorbs all of the red and blue parts of the white light, leaving only green which it reflects and hence you see it as green.

You might be wondering what this has to do with colour management. Well consider for a moment that if you ever print any of your photographs, you are changing their method of visibility from transmitted (what you saw on your screen) to reflected. The print is not its own light source (unless back lit….) and so must rely on reflecting the light it is being viewed under. Of course these are very different techniques by which we see, so differences between them are all too easy.

fig.4 - A graphical representation showing the concept of reflected light's ability to give colour. Where the object does not possess its own light source it relies upon reflecting light to be seen. As shown in this graphic a cyan coloured object, when lit with white light (a combination of red, green and blue) , will absorb all of the red in the white light, reflecting only green and blue, which, when mixed, give cyan. The other main difference between this and transmitted light, as shown in fig.2, is that it is a subtractive process. If we were to make an object blue in colour it would be a mixture of cyan and magenta. The cyan would absorb the red from the white light, the magenta would absorb the green; leaving only blue being reflected. It is only a small step from there to add yellow into our object to remove the blue and our object would absorb red, green and blue and so reflect no light. That would make it appear black. (graphic copyright of nimby)

The last thing I need to say about reflected and transmitted light is specifically related to prints. It is a major factor in why we can get differences between screen and print. It is just a closer examination of the difference between the two methods of visibility, but is especially important to understand. If we consider that transmitted light is a mixture of red, green and blue (which visible light is – as of course is your monitor), and that if we mix all of the together to their maximum values we get white (as discussed in part one section one) then how does this work for a print? After all the paper is white already, so if we then mix red, green and blue on it we just get lighter colours! Enter cyan, magenta and yellow, or CMY. What is clear is that a white piece of paper, before printing on, is reflecting all parts of the spectrum (RGB), hence it appears white. What we really want to do, as in nature, is to remove parts of that white light and reflect the remaining parts of the spectrum – hence giving colour. It is by no co-incidence that if you look on a colour wheel, as in fig.1, you will see that cyan is around the opposite side to red. Ditto magenta to green, yellow to blue. What this means is that cyan absorbs ALL red light, magenta absorbs ALL green light and yellow absorbs ALL blue light. Now we have a method to control which parts of the visible light spectrum are reflected, and hence we can cause any combination of RGB to be reflected by CMY. Simple eh? The CMY process is what is known as a subtractive process (RGB is an additive process), because as we have seen it removes parts from the visible light – therefore if you mix CMY together you remove red, green and blue from the spectrum. Which leaves you with…. nothing. As visible light is made up from a mix of RGB, if you remove all the RGB you are left with no light or black as we like to call it. So in theory to get black on your print you mix cyan, magenta and yellow together. In reality it doesn’t quite work out like this (surprise!), as it really isn’t possible to get inks so pure that when CMY are mixed it reflects nothing. Usually it looks kind of muddy brown. To get around this we add a real black ink to the mix, which by itself absorbs all light and appears black. This gives us the CMYK printing process which is the basis for just about all colour printing in existence. (K as in blacK, B is already used for blue).

Summary

So these are just a few examples of why different devices see colour in varying ways, and of course there are many more which I wont detail such as temperature, viewing angle, light conditions; the list goes on. The important thing to understand that without some intervention all devices, even if basically using the same principles, will display the *same* colour differently. This puts you in a position where you don’t know if what you are seeing on your screen is really what the printer will print, or even if it is the same as the camera saw. This is not a good situation to be in if you are interested in high quality output.

In the next instalment I shall discuss the methods by which we bring this all under control, the actual activity of colour management.

nimbyref:091006a Photo: Pad Prik Kaeng (Fried Spicy Curry) - by nimby. Canon EOS 5D.:endnimby

Split Toning In Photoshop

For some bizarre reason, I feel some sort of need to contribute my split toning technique to the internet. I promise to keep these random inputs as rare as possible!

Below you will find a screencast that takes you through my technique and although with the compression needed to fit it in here it is quite difficult to see the details, you should get the gist of what is required. During the screencast I also record an action, which you can download here. This will allow you to run the technique on any of your own images, and also if it is not clear from the screencast you can open up the action and see the steps involved.

One note, the embedded screencast is in MS WMV format, as this provides a nice small file – so if you are unable to view WMV files… sorry.

nimbyref:051006a Photo: Derwent Reservoir, split toned using the technique in the screencast below - by nimby. Canon EOS 5D.:endnimby

Get It Whilst You Can

After a slight break in posts, due to being busy with activities that actually generate some income, I am attempting to bring some service back to the blog, or kill it. For the time being I have decided not to kill it, as it still provides a way for me to get things off my chest, but as this doesn’t happen every day then the posts will become sparse. To fill it out I will continue to add random ad hoc BS and maybe even finish the colour management series.

The title of this post doesn’t, however, refer to the thread on which the future of this blog hangs, but rather something of much more worth, the passing of greatness in a sport I hold dear. Michael Schumacher has not died, but his choice to retire at the end of the current season is seen in my eyes as a severe loss to the Formula One slice of motor sport.

Many people loathe the man, but it should be clear to most people his accomplishments speak louder than any conceived ideas about his personality or nation of origin. For me being a racing driver isn’t about driving a car fast around a track – that is a given – but it is the absolute commitment to winning, where every meter of advantage should be fought and seen as a victory in its own right. Sadly, and this feeling is at the core of my sadness to see Michael go, there are very few contemporary drivers that show such determination.

Sure, on occasion Michael has taken it too far, but that will always happen when the desire is so great, the boundaries are gone and split second reactions that are driven by absolute focus to win seldom take into account being a nice guy or maybe even doing the safe thing. Let’s get something straight, motor sport isn’t safe. It may be a lot safer that it ever was – and that is a good thing – but the whole essence of it is danger. As I often say to comments made by the whinging Coulthard, if you can’t stand the heat, get out of the kitchen; for there are many skilled cooks who love the heat waiting to take your place. It is all part of the deal when you decide to become a racing driver; you should relish it not shy away from it. Of course this will explain the long and mostly mediocre career of David Coulthard.

In years gone by the rarely over aggressive tactics of Michael Schumacher were how cars were raced. If you look back at any of the great racing drivers of all time they all used pretty dirty tactics to get an advantage; it is part of the game. Jack Brabham’s favourite trick was to drop a couple of wheel on the dirt exiting a corner if he had someone close up behind him, to kick up some stones are other debris into their face. Back in that day, the dirt at the side of the track was real dirt and the helmets had no face protection, I bet it hurt. You don’t even have to go that far back to see two greats racing at the same time with the same absolute winning mentality. Just look at the fiascos caused by Ayton Senna and Alain Prost in the 1980’s. That’s how races should be contested, winner takes all. There are old and revered quotes from racing, such as, “second place is just the first of the losers” and that is how I see it.

The issue is that the majority of the new drivers may subscribe to such statements, but they don’t practice them. Bringing the car home in a nice safe third place to secure championship points is not exactly living by the sword. You certainly will not see Michael Schumacher doing that, even if it might be the most “sensible” option. Michael will fight for every meter of track position, as if it were the championship itself, he has hardly ever let another driver pass him just because it is less risky to do so, and the points are good enough. A prime example of this was in Hungary this year, where in mixed weather conditions Michael lay in second position, but on heavily worn tyres and close to the end he chose not to pit and change tyres. He knew that if he pitted that he would lose any chance of first place and lose the second place he was in – but if he wrangled that car around the track for 8 more laps he might take victory. You know the real great thing about that decision, his only rival in the championship was out of the race!! Alonso had already retired, so Michael could have easily pitted and changed tyre to come in a safe 3rd or 4th and take the bulk of the points from Alonso. That is what I want to see, Michael just wants to win and if it is impossible to win then every meter of gain is worth having. As it turns out his decision was to cost him more than 2nd or 3rd, as the car became impossible to drive in the last few laps, he lost some places and would have probably score more points if he had pitted for new tyres. But who cares? I don’t, what he gave us were 10 memorable laps of car control in adverse conditions and the sight of a man driven to win. Give me that any day than the Jenson Button’s of the grid (who won the race).

Looking at the contenders I really don’t see a lot to get excited about with the departure of Schumacher. Most of them are “drive for the points” types, who have already proved their lack of attraction in races where Michael hasn’t featured. Sure they are all fast drivers, they all qualify well, but there racing skill and determination – hence entertainment – are not there. I recall a race a couple of years ago where the leading 4 cars were within a second of each other for the last 20 laps of the race. I can’t remember who was in there other than Button and Alonso, but you can insert any two other boring driver’s names. There was not one single attempt to overtake in those 20 laps. They had all patently settled for their position, and just hoped the car in front will break. Jeez – racing by reliability. Maybe I am being harsh, but can you seriously imagine that if Michael Schumacher had been one of those drivers that he would not have tried an overtaking move?

Some people may think I am underselling Fernando Alonso. The thing is he is world champion, but look how he got there. I am not taking away from him that he is a talented driver, and there may well be more to him than I have seen but he had a car last year that just drove better than any other. That together with the fact that he is a very fast driver put him at the front of the grid on most occasions, allowed him to get in the lead and never require him to actually overtake (what I like to call “race”) anyone to win the race/championship.

To emphasise my point about the superiority of Michael Schumacher (do I need to?), you can just look at his record over the last 16 years. In basic terms 16 years worth of drivers coming and going could not ultimately find a better racing driver – many have come and gone, the opportunity for the best in the world to come and take his glory has been there for 16 years!

Do I think Michael Schumacher is the best racing driver of all time? It’s very difficult to say without pitting (pun) them all against each other. One thing is undisputable, he is the most successful. He does share with all the greats the sometimes uncontrollable desire to win, and is his car control in mixed conditions show that he has the skills to drive the older cars with less grip, so I would be pretty confident that if he were racing in J.M. Fangio’s era, along with Ayton Senna, Alain Prost, Graham Hill, Jack Brabham, Gilles Villeneuve, Nigel Mansell he would be certainly swapping podium positions and panel damage with them. If only it could be!

In all this gloom of loss, I find solace in two things. First is that Kimi Raikkonen has the potential to be a great driver. I noticed yesterday that upon his car breaking for what seems like the millionth time, he had no emotions one way or another. In earlier times when the car broke he threw the steering wheel out, kicked the car and skulked away. I guess that he just waits for it to happen now, and when it does he may even be surprised how long the car lasted. Next year though sees him in a Ferrari, and even though they have had their ups and downs in terms of performance, they have a good reliability record. I truly believe that Kimi will be showing the way next year, and I hope he proves me right about his inherent racing skills. The second form of solace I find is that I know there are other great racing drivers out there. Sooner or later one of them will be found, and will overcome the obstacles of getting into Formula One.

Until then though, there are two races left of this year’s season and it could not be better. The points position is that Michael Schumacher has brought Alonso’s 25 point lead down to zero – so what you are effectively seeing is a two race sprint to win the world championship. I don’t know about you, but in this do or die, winner takes all situation, my money is on a certain Mr. Schumacher. In my dream world they would somehow be tying on points as they enter the last race. If that were the case I would expect you too witness one of the greatest races of all time. Of course that mathematically cannot happen, but even as it is though, reliability aside, it is likely that the last race will decide it.

So, like him or loathe him, you have two Formula One races left to witness the most successful driver of all time ply his trade. Not only that you see him in a position where if he gives it his all and has a little luck on his side he will walk away world champion for the 8th time. Of course, Schumacher giving his all is guaranteed, and I suspect that it may lift the best from Alonso too, which is another aspect that we shall be losing – greatness inspires greatness – and Alonso will really need to dig deep into that historic book of dirty tricks. Bloody hell, how can you miss that!

nimbyref:021006a Photo: No not F1, but A1. A nice concept Formula - by nimby. Canon EOS 5D.:endnimby