Find a strong, definite colour – a painted door, for instance – and choose a viewpoint so that the colour fills the viewfinder frame. Find the average exposure setting – the one your camera’s meter recommends. Then take a sequence of pictures; all composed exactly the same, but differently exposed from bright to dark. Start at one stop brighter than the original metered setting, then stop down the aperture by half a stop each time… Arrange the five images together. Apart from the obvious fact that the five photographs vary from over-exposure to under-exposure, what other difference is there in terms of the colour?
My front door is blue, albeit rather faded, so I decided to use that as my subject. My control image was taken with an aperture of f5.6.
Hue is the quality of the colour – the name we give it, e.g. yellow, violet, blue. Saturation is the intensity of the hue, while brightness, or quantity has to do with the degree of lightness or darkness of a colour. (Painters change the brightness of colours by adding black, white or gray to a colour, or by adding another colour of unlike brilliance).
After downloading the images off my camera (no post processing done except cropping), I then uploaded them to ImageColorPicker.com so that I could obtain the necessary hue, saturation and brightness values. I do not have Photoshop and Lightroom 5 doesn’t have this functionality.
If we look at the Hue column in the table in figure 6 below, one can see that by stopping up and down from the control image using an aperture of f5.6 (highlighted in orange), there is a slight shift of about 2 degrees on either side in the hue of the door. Hue is measured as degrees around the colour wheel. In the Saturation column one can see that the saturation level in the overexposed image with an aperture of f4 differs by 17.02% (dull or weak intensity) from the control image and by 11.76% (intense) in the underexposed image with an aperture of f8. Conversely, the brightness levels increase by 17.26% (bright) and decreases by 25.88% (dark) respectively as can be seen in the final column. Thus when saturation levels decrease, brightness increases and when saturation levels increase, brightness levels decrease.
Freeman, Michael (2007). The Photographer’s Eye: Composition and design for Better Digital Photos. Lewes, England: The Ilex Press.
ImageColorPicker.com. HTML Color Picker [online]. Available from http://imagecolorpicker.com/ [Accessed 23 August, 2014]
Itten, Johannes (1970). The Elements of Color. Ravensburg, Germany: Van Nostrand, Reinhold Company.
Prakel, David (2013). Basics Photography 02: Lighting. 2nd edition. London: Ava Publishing.