When I initially started with photography and with a background of computers I had in mind of color management, calibration, profiling and all this little nifty things that all together construct color managed workflow art.
I needed a monitor calibrator just to make sure that I was within specs with my colors, and surely because I wanted a more controller printing workflow for my pictures. After a few months of waiting I managed to acquire a spyder3 elite package, which made me happy. But little did I know what I would be expecting in the future.
After calibrating my monitor, I happily enabled color management in my firefox browser (since there was no reason to have color management inside the browser without a properly calibrated monitor) and then it all started!
My first reaction was shock! I could see pictures oversaturated with evident color shifts in particular colors (blue turning to purple) in many pictures. Initially I was worried that my calibration was not correct that something was wrong with my computer or O/S, I started searching around the net for possible answers to my questions and I managed to come across a few sites with very informative content.
So let's start with basic color theory, what is color management? And what exactly does monitor profiling and color managed workflow achieve?
My intention in this series of articles is not to describe the whole color theory, this can be easily searched among the huge information found in the Internet, I will be targeting mostly to the basics of color management in the world of computers.
Image #1

<img src="http://i420.photobucket.com/albums/pp289/petrakisk/th_colorspaces.png" border="0" />


Let's imagine a Huge triangle, a triangle full of colors (check image #1), this triangle represents the color space we humans visualize (although it can't be exactly interpreted on a monitor we can still achieve a pretty nice render of them) and if you look closely you will notice the 3 corners known as RGB (Red, Green, Blue) the 3 basics colors. Now consider inside this triangle different color spaces (image #1) this color spaces you see are the familiar terms you always hear AdobeRGB, sRGB, ProPhotoRGB.
As you can see in the second image this color spaces differ from each other, since each is meant to be able to hold bigger color data from the other! From the above picture the sRGB (well known to most of us who do color management work) is the smallest (and yet the most widespread color space) and we could also say the Internet standard for photography (although this tends to change the last few years).
Now let's look to a third image, this image represents a new triangle this is the profile of a monitor (and more specifically of a laptop monitor, Acer Aspire 7720G) as you can see in the image the color profile is rather compacted in terms of color abilities in comparison with the sRGB. And if you look closer you will see that one end of it overwhelms the space of sRGB. Does all of this sound Chinese? Well it is kind of space science but we can interpret it more easily if we understand what exactly is happening.
Image #2

<img src="http://i420.photobucket.com/albums/pp289/petrakisk/th_sRGB_to_monitor_comparisson.png" border="0" />


Let's assume that you available color space (as rendered on the screen) is this Acer Aspire gamut (this is a calibrated profile) and consider we are working inside Adobe Photoshop and more specifically we have set our working color space to sRGB (I know we use AdobeRGB mostly, but for the example I say sRGB), as you can see from the image #2 your available color space us defined by the boundaries of the lines shaping the sRGB gamut. So now the question arises, what is exactly happening? As you can see color spaces are different, and monitor profiles are even more different, what does a monitor profile actually do?
Well a monitor profile instructs the software you use to render the colors of a specific color space according to you monitor! So a blue (RGB -> 0,0,255) inside sRGB gets correctly translated to you monitor, and that's the whole purpose of monitor calibration, it's a process for checking and measuring our monitor and graphics card, and mapping it as closely as we can to the correct color space.
Since monitors have then bad habit of interpreting colors differently depending the viewing conditions, monitor quality and the monitor intentions.
For example those nice glossy laptop displays (which are actually nearly crap in terms of color abilities, as you can clearly see in the gamut plot) have the tendency to apply extreme blue casts on them and make them even cooler and acceptable to human eyes under certain conditions.
The general theory under color management and monitor calibration is the ability to translate a certain color space into another and to be able to correctly render it for your display.
So if you are working in sRGB and have a specific color and change color spaces (say to AdobeRGB) photoshop (or any other editor) does some complicated math's to translate the color of the working color space to the destination color space (let's say sRGB) and additionally correctly render those colors to your monitor.
Since we mostly work on wider color spaces (more colors) such as AdobeRGB or ProPhotoRGB the software needs to be able to translate wider colors to narrow spaces, (for example we might be manipulating colors of the extreme corners of AdobeRGB they need to be able to translate to sRGB - a narrower color space - ), here comes the game of Perceptual, Relative and Absolute colorimetric you often see inside photoshop (but that's another story) and photoshop has also to translate all of this to your monitors color space in order to be able to correctly see a blue rendered to your screen.
The problems arise here; Different monitors and different capabilities, how many times have you wondered why does this specific monitor cost so high compared to the next one?
The answer is simple; If you use a gamut analyzer / plotter (outputting images as the ones previously described) you will be able to see the differences in color ability and accuracy among the monitors.
Monitors are manufactured with different standards which means that they translate and perceive colors in different ways! There are narrow gamut monitors, either good or bad and there are also wider gamut monitors. This creates a whole new arena of fights in color management, since each monitor can translate colors differently, and some can even translate higher gamut color spaces.
Image #3

<img src="http://i420.photobucket.com/albums/pp289/petrakisk/color_space.jpg" border="0">


In image #3 I have a comparison between my old by professional CRT monitor (EIZO Flexscan F56) and my laptops monitor (Acer Aspire 7720G - Note that the gamut space of the laptop is comparable to the one used by Apple for their Macbook Pro laptop - ) compared to the sRGB color space.
As you can see the laptop is really limited to color translation capabilities, this is the reason why many times a sloppy image inside our laptop monitor can translate to a stunning image in a wider gamut display, on the contrary EIZO has a wonderful response nearly matching the one of the sRGB gamut color space!
Now you can also clearly see why choosing a wider gamut color space inside photoshop is preffered, the EIZO outperforms (even marginal) in many colors the sRGB color space thus you can easily work on a larger colorspace and prevent color corruption or shifts.
But what is actually happening in such situations? Well this is the calibration process (I will try to describe this as simple as I can so that everybody can understand this).
Monitor calibration is the process of emitting color signals onto your monitor and the hardware calibrator, this signals get translated to a more correct profile for certain viewing conditions (this means that your monitor calibration is depended on the viewing conditions of the room, the monitor brightness and off course the light quality).
A hardware calibrator detects the color patterns appearing from the system on the monitor and sees what needs to be corrected in order for the colors to appear as correct as they can. It then translates all of this into math's and loads them into your graphics card applying a correction algorithm (you might have heard the gamma curve), this curves instructs the graphics card to render certain colors as they should be.
If your monitor is really sloppy after the calibration takes place you will notice (inside color aware programs mostly) the change of color representation of your images, you might notice casts that were not there before (most people find that they usually had a stronger yellow cast) but which you can clearly see after the monitor calibration!
What you where viewing and thinking to be a correct blue was not actually a correct blue but rather a hue shifted blue, from now on you can actually work on your images and be sure that you are viewing the correct colors. This is a significant step especially for printed workflows, since monitors differ and you can't actually be able to profile for everyone.
Image #4

<img src="http://i420.photobucket.com/albums/pp289/petrakisk/th_test.jpg" border="0" />


What happens now when your monitor is sloppy? (such as mine). A sloppy monitor (even calibrated) does not have the full potential to reproduce all the colors! Especially when it's a rather narrow monitor (in terms of gamut color space), what we need to understand in this step is the way applications translate colors to your monitor in a certain color space. To fully be able to perceive this lets take an example, let's say we are working inside the sRGB color space, create a new document and fill it with pure blue color (RGB 0,0,255). In a sloppy monitor as mine, you will receive the results as in image #4! Violet! What? Color management has just collapsed in your mind eh? Well actually it shouldn't! This is the correct representation of your monitor (remember? Your monitor sucks!) for the pure blue of the sRGB color space (since pure blue of AdobeRGB is different from sRGB, the same applies to all colors spaces, you can see the differences in image #1)
Why? Well you need to check image #5 (and I am going again to describe this as simple as I can - thus I will omit a few technical words just to make it easier - ). What is happening is that your color managed application (photoshop) is trying to describe something that it can't (on the specific monitor)! As you can see in the image my monitor profile is not that good in blues (actually is nearly dead in blues) color management tries to describe a wider gamut to my monitor profile by finding the closest match of the color for my monitor with the same apparent hue linearly (like drawing a line as you can see in image #5) that linear translation falls into a blue with a hue shift which is actually violet!
Image #5

<img src="http://i420.photobucket.com/albums/pp289/petrakisk/th_srgb_to_monitor_shift.jpg" border="0" />


No your monitor calibration is not wrong! Your monitor is actually the device that is not correct, monitor calibration tries to shift the curves to the closest possible correct match of colors, so it needs to shift a bit the reds, the greens, and the blues but the gamut is already defined, it cannot discover colors which the monitor cannot reproduce!
If you see closely the gamut space of the monitor your will find out that this monitor has a completely different intelligence of the blues (see the corner of blues that exceeds the sRGB corner? and most specific it is nearly a total different and narrow part of blue) which in my case (and lots of other LCD monitors) expands the sRGB space and even worse it does not even match in color terms! If you look again you will see that greens and reds don't shift that badly and that's why most of the times reds and greens match more closely to your monitor, it's the blues that get lost!
But you say your monitor supports 16million colors! Yes? NO! Most monitors are 6bit TN panels with dithering (sounds Chinese?). In simple words it can handle only 260K colors and the rest of them are software created with illusion techniques (called dithering), thus your gamut space is predefined and only virtually enlarged by magic techniques!
Professional monitors are designed to not need such techniques and to be able to fully reproduce colors on a wider gamut color space! (I am still in discussion with datacolor, author of the spyder calibrator in order to see if there is a chance of fixing this, at least to get deep saturated blues to be translated as such for the monitor).
Is you monitor 6bit? Well that's actually something you have to find, with a small googling you will be able to find out on the Internet. If you are on a laptop then by 90% you are on a 6bit display and you are already trapped in a tiny color space! And most badly you have a shift in the blues which prevents color managed applications to translating blues correctly for your monitor (It actually doesn't prevent, the monitor cannot fully reproduce the blue channel).
But shouldn't monitor calibration fix this? No! Monitor calibration tries to bring your gamut space as closely to the correct colors, because your monitor can be translating badly, you can easily imagine this with a small example. Consider you have a guy talking Chinese (like we are here) and now consider 2 translators. You don't know anything about Chinese and you only rely on the correct translation provided by the 2 guys.
If one of the two guys is not translating correctly, you won't be able to fully reproduce the saying of the Chinese guy! That's what your monitor is doing, it's translating not correctly before the monitor calibration, and correctly after the calibration.
So would revert back to sRGB for a monitor profile? No again, because the sRGB is just a color space and not the translation of your monitor, what you see is NOT what you get when using a profile not designed for your monitor! What you see with a calibrated profile inside color aware applications is the correct translation, if you use an non calibrated profile on your monitor, you might see blue, but on a calibrated monitor that blue could be cyan or even worse it could be a blue with a cast on it!
This is the first part of the tutorial, when I find time I will complete the rest of them, feel free to discuss or even correct me if I am wrong!

Some Questions and Answers on this topics:

Q: So could I use the monitor profile (even calibrated) of another user for the same monitor?


A:The answer is No! Monitor calibration is performed only for your monitor, and this means that it calculates all of the necessary parameters. This parameters include light condition, light quality, brightness, contrast. Even if your monitors are the same, it doesn't mean that they will be rendering colors the same, my monitor might be a bit more "warmer" in color representation than yours, that's totally reasonable since monitors and hardware cannot always perform exactly the same. So the answer is definitely no your can't use the profile of another user


Q: I have software calibrated my monitor, is that good? or similar to hardware calibration?


A: Hardware calibration is highly efficient, and even then there can be slight different results from hardware to hardware. There is no way you can actually calibrate your monitor with the eye, and thats because your eye always tries to compensate for the current viewing conditions. Monitor calibration is actually performed to bring as close as it can the monitors colors to the correct representation of them (and this depends on your monitors capabilities as well).
Furthermore the corrections performed by a hardware calibrator cannot be performed by a software calibrator (technically speaking). This is also the reason Adobe has stopped producing and distributing the Adobe gamma. The only way to fully understand this, is to see a monitor before and after the calibration, you will be able to fully understand that the result would not ever be feasible with only eye calibration.


Q: I print my images on my printer and I get accurate results, without ever calibrating my monitor


A: You may be lucky, but you also need to describe the way you print, if you let Adobe manage the colors when printing then what you see is what you get, this changes from the moment you submit your files to a 3rd party printing company. That's where everything gets mixed up!
Additionally what I need to stress out is that monitors are not that sloppy, don't expect after calibration to see a huge shift! More specific you will see that your probably had a color cast that prevented you from developing correctly!.
In my monitor I had a strong blue cast, all of my portrait shots AFTER monitor calibration have a strong yellow cast, thats normal in terms of color management since my monitor before calibration was on the "cool" side and I would try to create warmer portraits. After the calibration I was able to see that.


Q: Does it mean that if I calibrate my monitor I will be able to print correctly?


Monitor calibration does not mean that color managed workflow is dead. It does not mean that if you develop a picture nicely in photoshop it will be printed exactly like that! You still have to soft proof for the media you want to output. If it's a monitor you have to soft proof for a dummy monitor, if it's a printer you need to soft proof for that printer (ICC profiles). Monitor calibration is performed so that you can actually see the "truth" on your monitor, to be able to render colors as close as possible to the correct ones.