Color temp of speedlights?

[Jannie]

The color temp of my 580EXII's is pretty cold compared to my Elinchrom BX400's so I gel by eye, sometimes with a 1/4 or 1/8 CTO, but sometimes it's still weird and sometimes I don't seem to have to do anything.

Is there a way I can shoot a white or grey card, put the image in lightroom and read the color temp in a way I can shoot multiple tests with different gels on the lights to come up with a gel that I want to use most of the time. This of course would also have to be adjusted with the different umbrella/modifiers that I use because they all seem to put out different colors if you try to use different modifiers on the different lights.

I'm just looking for a way to do tests and come up with a sensible reference for gelling by test. Yes I know often it's best to do it by eye but this has come up so often that I'm looking for a better solution.

I realize it would be best to use all the same light sources but I often find that little fresnel lens on the speedlights a great asset in product work, offering something I'm not getting out of strobes and I'm not about to spend the money on a large expensive fresnel strobe and rather light the smallness of the speedlights and how easy it is to confine the light beam.