Real World Color Management

After two weeks of idling, I am updating this blog again. I didn't really go idle, but was reading couple interesting books in preparation of assignment 4. Of course, I can't just start assignment 4 right now (sadly). There is a long chain of backlog issues I need to update before doing anything new.


1) Blog the reading for section 3, colour, which I am going to do now.
2) Blog the reading that is recommend by my tutor. That is the book "Way of Seeing" by John Berger
3) Post the remaining reshoot for assignment 2
4) Check if my tutor has feedback on assignment 3, which I have submitted a month ago. 
5) The long chain of exercises that lead to assignment 4 (Mine, how many of them are we looking at?)


First come first, the reading for Colour. Back in February, I pick up this book call "Real World Color Management" by Bruce Fraser, Chris Murphy, and Fred Bunting. It is a very interesting book to start. It takes forever to read once it passes the middle, and I can't quite make it to the end. Why so? Because the theory is interesting, and why one need to pay attention of the colour consistency between varies input and output device is important. Then when it gets to actual calibrating, there is very little I can do with my existing devices.


The book begins with discussion on incoming light (electro-magnetic wave), and sensors in our eye (the cones and the rods). The wavelength sensitivity on the three cones cell link nicely to the R, G, B channel in the CCD sensor. 


The interesting concept introduced was something called metamerism. The way I understand it is if I send you a photograph, the computer can code it in a sensory input (RGB, so is the trisimulus value) and reproduce the same thing I see in your output device. It doesn't matter the internal function of the monitor and how it generates light and mix them together, but the existence of metamerism allows us to break colour and code them in just sensory trisimulus value. Of course, for monitor (output device), it makes sense. It doesn't work if we are looking at object reflected light under different light source. For example, the same sculpture displayed under sun light or fluorescent light, the colour may seems different even though the material that made the sculpture doesn't change. The easiest example I can think of is photographing dance under stage light that has colour. And of course the custom looks different compare to what it is under sun light.


Then the book introduce different colour spaces, with the aim to keep colour consistent as we go from device to device, regardless it is an inputting device (ie camera), or outputting device (ie monitor and printer). Along with device profile, they specified the reproducible colours in one to the other devices. Then when the device is incapable to output certain colour, a colour management scheme will map it to something else. This process is called rending. Apparently, the rending error is smaller if there is more colour bit size. 


It is all very interesting until I hit the calibration part. The truth is, I don't have any measurement device to check, well anything at all. A profile maker, and a colorimeter cost more than my monitor, printer and camera all together. I checked with other people in the OCA forum about this. I have a very old Dell monitor (bought back in 2005) and now the IPS panel can displays a much larger colour depth. They suggested that if I want to calibrate the monitor, I should invest in a entry level spyder and a better monitor. At the moment, I prefer spending money of fixing my tripod, and the broken wide lens first. 


So what is the take? We have probably underestimating the depth of the colour theory. It is great to think (or hope) the other people sees the same thing as we do as we capture the screen, but the truth is not that simple. When one day I have to think of having my work published (or even printing work to submitted to OCA one day), I should be aware of the issues with device profiling.