Massimo's photoblog

One of the advantages of shooting in RAW format with my Nikon D100, is that there are no white balance or color corrections applied to the image. This gives a lot of freedom in post processing, as these corrections can be applied at the time the photo is actually imported into photoshop, and one can experiment different settings.

Changing white balance, for example, can give interesting results. The operation is necessary to correct for the color casts that the environmental light creates on the image. Without white balance correction, a photo taken in a closed room with electrical bulbs (the regular ones with a tungsten filament) would have a strong yellow cast. This happens regularly with film cameras, unless the effect is corrected in the printer room, or a “tungsten light” filter is used. This filter basically removes yellows and enhance blues, to compensate for the cast of the tungsten filament light, which is not the same as the “natural” solar light. Note that the same happens with our own eyes: we don’t have a “tungsten filter” in front of our eyes, but our vision circuits in the brain corrects automatically for the cast so that the colors of familiar objects or persons appear as we expect them to be.

Digital cameras have automatic settings that do the same, and remove color casts before saving the JPG file. Some cameras are more sophisticated and allow user control over the white balance settings. Other cameras allow the white balance correction to be applied later when importing the photo into the image processing software, like Photoshop. As I was saying before, this last option is what I like because gives me more room to experiment.

The standard setting for this photo would have been the one for “cloudy” or “shadows”, as more of the light in the image is not direct sunlight, but reflected (scattered is the correct physical term) light from the aerosol particle in the sky. This usually produce a blue cast that is corrected by the “cloudy” or “shadow” setting of the white balance (see for example the “last dragon” image that was taken the same day in the opposite direction, and doesn’t have any color correction applied and it is thus very bluish). This would have produced a uniformly red sky, which is what you would expect in a sunset, and is what my eyes were actually registering as I was watching. When reading the RAW file in Photoshop, I however tried the “tungsten” white balance setting, that removes the yellows and enhances the blues. The result is the photo above. Removing the yellow components from the sky resulted in a stronger gradient in the transition from the red sunset light and the blue sky, and the individual red clouds are more contrasted on the background.

The photo above is not exactly what my eyes were seeing that night. It is the product of a digital manipulation, in a way equivalent of putting a filter in front of the camera. Is always difficult to balance how much manipulation actually improves an image without overdoing it. People have different tastes and this threshold can vary. Where is your threshold? What would do you do in this and other cases?

...

Before closing for today, I would also thank David of unplugged that posted a very nice review of my site on his photoblog (which I recommend to visit; there are some really nice images there).