UniWB - Practical Use?

[keithrj]

Tomczak, I read an article on UniWB that describes a very easy way of setting up your camera to show a histogram on the RAW data. The idea is to create a custom WB that has the RGB multipliers all set to 1 so that no change is made to the RAW file for WB.

The quickest way to get this custom WB is to take a photo in Manual mode with a high shutter speed, smallest aperture and the lens cap ON with the eyepiece covered. This should produce a pure black image where all the RGB channels are equal, i.e. no colour cast. Select this image as your custom WB.

What the camera does is look at the black custom WB image and sees that there is no colour cast to adjust for as all the RGB channels are equal. The camera then sets all the RGB multipliers to 1 which results in a JPG image that almost exactly matches the RAW RGB data.

Your JPG thumbnail will look quite strange but the histogram will reflect the RAW data, which is what you are after to see if any of the channels is clipped.

Now for one caveat: this may only work with Canon cameras so try it with your own camera to see if it works.

Here is the source of my description above: http://photography-on-the.net/forum/sho ... p?t=485349

I hope this makes sense.

[keithrj]

Here is a very comprehensive article on UniWB and includes details on custom WB:

http://www.guillermoluijk.com/tutorial/ ... dex_en.htm

There are also RAW files available to download for a number of cameras to be use as custom WB images.