calculations in custom columns

[Wojtek]

Is it technically possible to add some calculations to custom columns?

I'm thinking about something like this:

calculate the megapixels (with 1 digit precision) of an image

MP = round((wdx4i.pixw * wdx4i.pixh) / 1000000), 1) "MP"
example picture size 2400 x 3600 pixels would result in MP = round((2400 * 3600) / 1000000), 1 ) = 8.6 MP

This is just a 'simple' example. The calculations could be much more complex.