Wednesday, January 25, 2012

Photo rescue, or what to do when the white balance fails you

The weekend before last I went on a photography expedition. I had meant to make a day of it and go out to Reykjanes, but I ended up a fairly short way from Reykjavík, on the outer edge of Hafnarfjörður where there are lots of abandoned farms near the aluminium smelter in Straumsvík.

I was shooting using several different settings, but mostly I was using the shutter priority program. Which, it turned out, had the white balance setting on manual, set to balance the light for incandescent bulbs. This, in simpler terms, means the camera automatically adds a blue cast to all the photos to compensate for the warm yellow of the artificial light. As there was a blue sky, and the shadows were blue, it made the photos very, very blue. I though the photos looked a bit blue when I looked at the camera screen on the spot, but then I though maybe it just looked that way because after all it was sunny and you can't see too well on the screen in the sun. When I got home and uploaded the photos to the camera I saw different.

Original, unedited except for a slight crop and decrease in size:

I started by swearing a bit to alleviate my feeling of stupidity and then went googling to find a solution to the problem. I have only very recently begun shooting raw and wasn't really in the mood for a crash course in image correction for that format, so I decided to tackle the .jpgs. I have not taken any courses in digital photo editing, except for a day of Photoshop many years ago which mostly covered layer masks and cloning, and I have always learned to use the software as I went along. White balance was something I had hitherto been able to fix quite well using the colour balance tools, but not in this case. Google brought me to a blog which explained what I wanted to know: there is a white balance correction filter in GIMP. You go to the Color menu, open the Auto sub-menu and choose White Balance. The rest is automatic. I used it on the above photo, reducing the cast considerably, but more was needed, so I started fiddling with the colour balance until I found a solution I could be happy with. It still looks a bit blueish and looking at it on the screen I am using now, it appears that I have added slightly too much red, but it's still much better than the original:

Of course there is a quick and dirty solution that will solve most white balance problems in one fell swoop: Desaturation.
In this case I like the black-and-white rendered image best of the three, although it still needs work - possibly a bit more contrast:

Camera: NIKON D7000
Date/Time: 2012:01:21 13:27:24
Focal Length: 22.0mm (35mm equivalent: 33mm)
Exposure Time: 0.0040 s (1/250)
Aperture: f/22.0
ISO Equiv.: 800
Whitebalance: Manual
Light Source: Incandescent
Metering Mode: matrix
Exposure: shutter priority (semi-auto)

No comments: