Wednesday, 16 November 2011

The White Balance Case

Some years ago, I was a very happy owner of a Canon SX10IS and taking pictures of almost anything I could find in front of me because this camera was a small wonder (by then, at least for me). It was not that small that I could carry in my pocket, but I still could take it everywhere almost unnoticed.

Talking about silence, I muted all the sounds it produced like clicks and clacks and, because of its LCD that could flipped, I was able to take pictures in any places where pictures were not allowed. Pretending to be carrying the camera on my lap, I would twist its LCD to my convenience, take a brief look at the scene there  and then - click - without a sound! This is something that I cannot do with my DSLR now because the mirror always makes that clack-clack music that anyone around 10 meters can hear, specially if you are indoors.

Just a clarification: I am not a spy nor I have the habit of infiltrating myself in secret places just to document in pictures what the world is doing under the covers! Rather, there are situations where you need to be as discrete as possible so that your subject continues acting normally or you don't want to disrupt the moment like when you are in a concert (provided they allow you to take pictures, see my post about Japan), a mass or a funeral, you name it.

Point made, let's continue.

I am going to talk about white balance and how it changed my photography life, if such a technical detail would be able to accomplish such a feat! Therefore, let me just go a bit down to details and at least say - in lame words - what is white balance if you are interested and/or you don't know it. Otherwise, feel free to skip the next few paragraphs.

In digital cameras, right after you press the shutter button and before you see the resulting picture in your camera screen, lots of things happen with the light that came in through the lenses, hit the sensor, which produced gazillions of tiny electric impulses, all of them processed by a small computer that produced the image, which is finally written to your memory card, while being displayed on your screen.

Roughly comparing, the lenses are your eyes, the sensor is the retina, which produces electric signals to your computer - sorry, to your brain - which converts these signals into a sensation that you would describe as an image and finally keeps it somewhere as part of your personality and experience in life.

Although similar, let's not talk about how complex or simple a human vision system is in relationship to the camera's; instead, let's just say that both the brain and the camera's processor take the signals and transform them into the best images possible by using "past experiences". Before you jump in disgust, let me explain what is the meaning of past experiences.

Our brain has years and years of experience on how to render an image: it knows exactly what is the meaning of a crooked image, a distorted line, the interpretation of colors under various environments, among other abilities. One of these is to tell us that snow is white and represent it as a white sensation even though together with the snow there is the Sun, shadows, trees and other objects to make the scene very complex.

The processor of our camera, on the other hand, also has years and years of research and its engineers made all the best to feed the processor with tricks to produce a nice image. But, this is not enough and, in many situations, the resulting images are just a composite of the average signals produced by the sensor which makes, for instance, the white of the snow to become blueish. Basically, a camera does not know that snow is white and confuses everything.

That's why cameras have those Scene Modes where we tell the camera that we are photographing snow and not the sky.

In essence, by choosing the Snow Scene, we forced the camera to "balance the white" to produce white snow. In the same way, there are many other settings like the yellows produced by some lights, the intense cast produced by the Sun, etc.

Another point made, let's continue once more.

At that time (that is, some years ago), white balance was just a synonym for Tungsten, Sun, Clouds, etc, which I liked to play to see the results in my pictures. Look at this one taken in Rio de Janeiro from the back of a narrow, crammed, popular and delicious restaurant in Santa Tereza. Since this restaurant was formerly a regular single level house, I had to go through its kitchen to be able to reach the balcony in the back. I conveniently placed my camera at the edge and clicked:

Santa Tereza in Rio de Janeiro, a beautiful place with houses of all types, delicious restaurants and pleasant view from Rio.
Being a point and shoot camera, the SX10IS only produced JPG format pictures and, consequently, the white balance is defined at the moment of the click; you can correct it to some extent later in post-processing, but most of the light and color richness is lost when the JPG file is written to the memory card. This is one of the reasons why I now regularly take RAW pictures but this is a subject for a later discussion.

Anyway, the picture above most probably froze a tungsten setting for the white balance as a result of one of my experiments. The other pictures of the same subject with different settings I discarded. If you pay attention, you are going to notice that there were no such thing as green nor blue lights at that place and it later became clear to me that I was either a genius by being able to capture such an image or I did something very wrong that coincidentally produced something interesting. That raised me a flag that there were more things in Photography that I was ignoring.

I haven't fully recovered from this "The White Balance Incident" when I took this other picture at the Rideau River, almost needless to say that it was at the sunset:

Rideau River, Manotick, Ontario, Canada.

Wow! I was amazed by the result! And all I did was to set the camera on the tripod, fiddle with the white balance, point and shoot. That was it! At that pace, I could be a great photographer!

Well, not so fast, buddy! It was too good to be true and I decided to learn some things about Photography. Bottom line, in both cases I just pressed a button. Not much more than that. Ah! I forgot to tell a secret: I always used the camera's auto mode. Yes, Sir! In capitals: Auto Mode!

Something was wrong and I found it out very soon when I seriously started getting the technicalities of a great picture. I was focusing my success on two pictures and I conveniently forgot thousands of others that were full candidates to be thrown in the garbage bin.

The end of this chapter is that I knew nothing about Photography and that these pictures were just good  accidents. Like any accidents, they don't happen when we want; they present themselves unexpectedly and we need to be prepared for them in order to take the most of the situation. For instance, these two moments above will never repeat themselves again maybe in my lifetime. I was fortunate to be there and I know that there are other different moments in different places where I could take profit as well. But, these ones, most probably, never again!

Let's see one example. I took this picture in Prague (I don't know the name of this church).

This is the original image. The orangy/yellowy tones of the walls almost obliterate the presence of other source of lights. 

After the white balance correction, the blue and green source of lights  are very clear, specially at the top of the church, at its entrance and on the building at the left. Also, the blue sky is very clearly seen.
It makes a big difference before and after applying a simple white balance correction as the right colors of the scene start to show up. In particular, it is amazing to see the deep blue sky as opposed to the black background from the original picture.

My suggestion to you, reader, if you are seriously interested in Photography and you are learning like I am learning, is to read and practice a lot. Items like white balance, light, color, aperture, depth of field, exposure time, ISO, file formats and much more are the bare minimum to give a solid background to start to understand how a great picture can be taken.

It was in one of these readings that I stumble over the RAW format, its advantages and disadvantages. Next time, I will tell you how I managed to take RAW pictures with my Canon SX10IS. I am sorry? Did I hear you saying that you took RAW pictures with this point and shoot camera? You gotta be kidding!...

For more and far detailed information about white balance, please refer to these places:

A very technical discussion for geeks:
Cambridge in Colour

Another great article less technical:
Ron Bigelow

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