An exercise in Digital Image Processing
(alternate title: What lurks in the shadows.)
During July-August, 2009, I was fortunate enough to travel through Botswana's Okavango Delta and of course took numerous wildlife photos along the way. One afternoon I had the camera with telephoto lens set up and was taking some shots of an African Fish Eagle some distance away, when I became aware of another bird in the undergrowth nearby. The bird, a Francolin, was in fairly deep, broken shade, and I quickly got a couple of frames before returning my attention to the eagle.
It wasn't until returning home that I had a proper look at the resulting digital file and realized just how poor the light was and also how far off my camera exposure settings were at the time of taking the shot. The resulting file was heavily underexposed but I decided to make some adjustments to see if anything worthwhile could be salvaged from it, to find out "what lurks in the shadows". I won't pretend that the resulting image has any great artistic merit, yes, I wish that distracting foreground leaf wasn't there and that the bird was doing something more interesting than just sitting there! However, readers may find it of interest to see what can be achieved with digital processing of an image file that initially appears to be a lost cause.
The image was captured with the Canon 5D Mark 2 with 500mm lens at F6.3, shutter speed 1/1250 second at ISO 200. Digital processing was done with Adobe's Lightroom 2.6 and Photoshop CS3.
The original file. Heavily underexposed with only the beak and eye of the bird clearly distinguishable in the deep shadows. The only processing here is the addition of my copyright stamp.
Step one was to increase the exposure by 2.3 stops in Lightroom. At least now we can see the body of the bird and the emergence of some shadow detail.
Step two was using the fill light slider in Lightroom to open up the shadows further. Fill light setting +46. We now have more detail in the leaf litter in those shadows but the overall colour temperature is very cool.
Step three, increasing the colour temperature from the initial 4250 to 5450 Kelvin. The bird's feathers are now their rightful brown tone and not cyan. The earth in the foreground and the background leaf litter have also warmed up.
Step four, cropping. Now that I can actually see some of the details, I know I want to crop the image. Notice there is the head of a second bird at the right edge of the previous image? In the original file it wasn't even visible.
Step five, selective colour adjustments. I'm still not happy with the colours in the shadows, whilst the bird is now looking better, the background shadows are still too cool with a cyan/blue cast. I increased the yellow saturation +7, reduced the blue saturation by -48 and reduced the purple saturation by -67. These adjustments helped with the background but had little impact on the bird itself as there are few blue/cyan tonings there.
Moving over from Lightroom to Photoshop, I felt the bottom left corner was too distracting and so I desaturated the yellows and masked the effect to just the corner. Then I selectively sharpened the bird with extra sharpening on the eye and beak. The shadow areas, particularly being so underexposed, show considerable noise, so noise reduction was been employed and masked to just the shadow areas. Finally I've used a dodge and burn layer to add a subtle vignette.
As I pointed out in the earlier paragraphs, it's hardly an award winning photograph, but I think does give a useful demonstration of what can be achieved with the current digital processing software. There is no strict right or wrong way to process such a file. For example, the decision to crop the image, and the extent of the cropping, is one that in many cases would have been made earlier in the process. Also it would, of course, have been better to get the exposure right in the camera to start with, or even to have used some fill flash. The issue of noise is most apparent in those shadow areas as well.
I guess the take home point out of all this is that sometimes an image that looks like it's only fit for the recycle bin, may be worth opening in Lightroom or Photoshop just to check. A quick adjustment to the exposure may be sufficient to see whether it's worthwhile continuing or not, to see whether there is something interesting "lurking in the shadows".
Kevin Dowie March, 2010.