Putting the red back into underwater photographs

Question

I've just come back from the Red Sea and took my camera along on most of my dives. I do have an external strobe, but for most of the shots the light was so strong that the camera didn't fire it. The result is that I've got lots of shots with a strong blue cast.

I can always just play with the hue/saturation in Photoshop, but it occurred to me that a quicker method might be to stick a red layer over the top of the images. It seems to me to be essentially the same as the red filters that are often supplied with housings. Has anyone ever tried this and what were the results like?

Answer 1

The way to achieve better white balance during the shoot (and also better exposure on green and red channel) is to use actual physical filters in front of your lens. According to this article, the filters meant to compensate fluorescent lightning are also applicable for underwater photography.

To fix it during post-processing, I'd suggest white balance tool, especially when you've shot RAW, if there is something neutral gray on your picture, the gray picker works well, otherwise you have to tune the color temperature slider along with tint (which might be tricky).

When your pictures are JPG, you can try curves tool and neutral gray picker specifically.

You can find a more general White Balance question and answers here: What is the meaning of "white balance"?

Disclosure: I've never taken nor post-processed any underwater shots.

Answer 2

I would recommend using the Photo Filter features of Photoshop. Photoshop directly supports simulating color balancing filters, and has several presets that match official warming or cooling filters (i.e. 81A, 81B, 81C). You can easily add an adjustment layer for a "Photo Filter", select the filter you want to apply, the density, and whether to preserve luminosity. You can apply the same filter several times, or apply different filters, as if you had stacked the filters on your camera. This should take care of the problem, although if you have an extremely strong blue cast, you might want to try adjusting color balance a bit first to produce a more natural end result.