16/01/2007

The facts on colour


I did state earlier in this work, that I would not get too technical here, but for those whose images are not turning out as expected, colour or light wise, perhaps a little knowledge on this subject may give you an understanding of what can go wrong, and frequently does, as far as the colour and brightness of your images is concerned.
But first, a little bit of history. It was Isaac Newton, in 1666, who demonstrated that light is the source of all colour. This was determined after he passed light through a glass prism.

It was, however, not hot news in those days, because there had been demonstrations of the like prior to this, but until Mr Newton's experiments, it was deemed that the colours came only from the glass itself.
What Mr Newton did that was different was, he added a second prism, which he found re-formed the light and the resulting conclusion was, that light was made up of all the colours in the spectrum. Thereby adding all the colours in the spectrum to get white light.
You can look at colour as being warm or cool and the actual warmth and coolness of the colour is given a temperature rating. This temperature is in degrees Kelvin
(Don't ask me who Kelvin was, that's another story).
When we look at a sunrise or sunset, we tend to accept that the light is producing a "warm" glow, when in fact this warm yellow/orange colour is actually at the cool end of the spectrum. Whereas, the blue colours are at the hottest part of the scale. That may sound odd, but remember, the blue part of the flame from a gas jet is the hottest part.
When you fire the electronic flash on your camera, it gives off a white light of around 5500K, which is about equivalent intensity to the light you would have outdoors at about midday.
At the bluest, or hottest end of the spectrum, is at about 12000K and the very opposite red end is around 2000K and the light from a generally cloudless sky at midday, which is known as "white" light, is usually about 5500K, but this can vary according to time of year and atmospheric conditions.
During the night, or in the very early hours of the morning, before the sun rises, most of what we look at is in black and white. Then as the sun slowly peeps over the visible horizon, its rays pierce the densest part of the atmosphere, where the blue end of the spectrum is filtered out, leaving that warm looking colour cast on all exposed surfaces.
The shadows will take on a bluey look, but this should be burned off as the day progresses, causing them to turn black around midday.
It is at this time of day, when the sun is at 90 degrees and directly above, your polariser will be working at its optimum best.
Midday light doesn't have a particular colour cast, but it is deemed by photographers not to be the best time of day for image making, because of its potential to create deep, contrasty shadows and flat, hazy colours in landscapes and outdoor portraits.
As the afternoon progresses, the light begins to warm up again, making it more desirable for photographers.
Even though the human eye cannot detect these subtle differences in colour temperature, the camera sees it as it is and will show it in the resulting images, when you will look at your photos and think that all is not as it should be, but the camera doesn't lie and two different people will not see the same colour in the same way.
Being involved with paint sales, I have come across this problem many times.
Nowadays however, you can make these colour adjustments simply by putting the images on a computer and subjecting them to a little Photoshop treatment. Just think of all the images that have either been tossed away, or just left at the bottom of the heap, because they didn't have the right colour or light consistency. Hmmm, perhaps I could make a start.....No, on second thoughts.....But maybe one day!
It is now possible, on some of the newer digital cameras, you have the option of adjusting the colour and/or lightness of an image, by utilizing the in-built colour correction filters. I can do this with my camera and it also has an automatic white balance (AWB) built in, which will correct fluoro, or incandescent light to white light automatically, if you have that setting enabled.
If anyone needs to know more on colour correction or any other "Filters", please see my chapters on that subject.
Well, I trust this has enlightened you to some degree and I do hope it wasn't too technical for you.



"Here's another bright idea!' . . .
When viewing an image, the eye can be drawn away from the main subject by the inclusion of unwanted elements and colourful or bright parts in the scene, so when composing your shots, be aware of any inclusions and/or intrusions that may be distracting to the eye. A slightly different angle of view can eliminate such distractions.