adjust color temperature of different photos

[jakeelee]

Hi,

I want to build a panorma picture (extra wide) out of 3 single photographs. My problem:
due to different light situation the colors of the three pictures are not the same:



how can I adjust left and right picrute to the colors/color-temperature of the middle picture?

I know how to add the 3 pictures seemles, but I dont know how to adjust colors.
Please dont give me hints for adobe photoshop or GIMP for I dont have them.
Thanks in advance