any good photo editor has a color balance tool
I use PSP X4 and it's tool is quite simpe, pick any part of the subject that should be white, or a shade of grey (i.e. no tint to red, blue or green desired) and click on it, and it then corrects the whole image applying color correction to make the item picked devoid of color (neutral grey) you can then change the color temperature to add a blue or red cast to make the photo colder or warmer as you wish.
this works even on jpeg, but my experience is that the result always turns out too cold (high color temperature) so I often warm the results a little by reducing color temperature
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