Colour Casts / Scene modes

In this post I'll make a few observations about colour casts (white balance) and Scene modes. Before linking these two seemingly disparate topics, let's start with colour casts.


Here are two shots I took the other week, direct from camera. Both shots are two perspectives on nearly the same scene in a pine forest but look at the blue-ish colour cast on the left-hand image! The two shots are taken from locations less than 10m apart, but what I didn't factor in was the difference in ambient light.

The scene on the left is lit more by the open sky above whereas the scene on the right is getting more direct sun-light. For both shots, I left the White Balance setting at "Daylight". This works fine for an outdoor scene lit by sunlight but causes a colour cast when the scene is lit by the overhead sky (similar to cloud or shade).

There are three solutions for getting the right colours...

1. Always shoot with the WB set for daylight then correct later with an image editor;

2. For each shot, choose one of your camera's WB presets such as "Cloudy" or "Shade". This "warms" up the image but it may be too little or too much;

3. For each shot, set the WB manually by placing a white coloured object in the same light as the subject (assuming your camera has this feature).

I had to go with option 1 and here's the result. The two images now appear in the same light:




Now, how do colour casts relate to Scene modes?

I haven't experimented with Scene modes on my camera (for various reasons), but another person in the walking group sent some images they took, from the same walk. The images suffered from all sorts of colour casts ranging from blue, to green to yellow! Novice camera users tend not to notice this type of issue with their images.

Intrigued, I asked this person how they went about taking a shot and discovered they make extensive use of Scene modes. Camera manufacturers promote Scene modes as a way to "simplify" taking pictures but novice camera users have little idea what a particular Scene mode actually does and often the manual (if read) is vague.

For the record, a particular Scene mode is a built-in programme that puts a certain bias on aperture, shutter speed, ISO, white balance and flash. In the same vein, the Auto mode on your camera is really a Scene mode with a bias for "general photography in daylight (or flash)". Provided everyone is shooting in daylight with the same notion of "general" photography the Auto mode can be effective in producing a reasonable shot.

So, how does this explain the unusual colour casts my friend experienced? By switching from one Scene mode to the next for different shots, they unknowingly altered the white balance setting, away from what was actually required by the shot.

For example, for a shot of a toadstool on the forest floor my friend dialled the "Food" Scene mode. I have no idea what a "Food" scene mode is set for but I'm sure it does not cater for toolstools in a forest!

Feel free to use a Scene mode, but I would recommend you experiment first to get a feel for what the Scene mode does to your images (compared against the Auto or Program modes).