Tuesday, 13 December 2011

Exercise: Managing Colour

This exercise is all about getting the right colour balance within an image. We are asked to find two of more images that have a definite colour cast and to use the RAW converter to correct this cast, or if using a JPEG image  to use 'grey dropper' tool within the levels or curves adjustments.

I chose the first raw image taken under fluorescent lighting with the camera set at auto white balance. The squash courts were actually a pastel yellow, as opposed to white walls, and this has helped to give an ugly yellow cast over the image, which is also under exposed slightly.

To correct this image I first changed the white balance setting to fluorescent, however it still need a minor tweak with the temperature and tint sliders to give an overall good colour balance. I used the white of the shoes and the player's T-Shirt as indicators. After adjusting the exposure and brightness so that the image has full dynamic range I then felt that the colour had been corrected.

Although taken in RAW I have used the following image to show similar results in a JPEG. This image was taken on a sunny day with AWB but from recollection, and the shadows present, it could have been taken standing in shadow. Either way it has led to an unpleasant magenta cast to the image.

To correct this I created a levels layer in photoshop and used the grey dropper tool to click on the grey concrete payment in the background. This instantly shifted the colour balance to a very acceptable version.

As a separate exercise I also corrected the same image in the raw converter simply by changing the white balance to 'Sunny' and boosting the contrast to produce the following version, which is far better than the jpeg conversion.

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