Problem with color calibration on mosaic images

[TobiasLindemann]

Hi everybody,

since some weeks I am working on a multiple mosaic picture. As this is is my first attempt, I have some problems that I haven't with single images.  Especially to archive a matching color calibration is a big problem for me. With the PI calibration method I get completely different color impressions. So I had a look at the Excalibrator software, which should give accurate colors. But even with Excalibrator I get different colors. In the pictures below you can see two imagesets with the same region. Both pictures I have calibrated in Excalibrator with the same adjustments. You see that the galaxy in the upper picture is more reddish and in the lower it is more yellowish. Both pictures are taken with the same DSLR, but I have to admit that I have taken the lower picture one year ago while the camera was unmodified. The upper images where taken without IR-filter.
Surely I can calibrate on the same galaxy and get the same colors, but I have 4 more mosaic images where this galaxy is not present.
Do you have an idea how I can calibrate my images?
If you want to have a look at the linear fits images, you can download it from here:
http://tracking-station.de/PI/part1linear.fit
http://tracking-station.de/PI/part5linear.fit 
This pictures are not color calibrated, only DBE is applied.

Greetins
Tobias

[georg.viehoever]

Hi Tobias,

I dont see how you can make two images taken with different filters match. In your case, the change is in the IR filter.

Just imagine you would take an image with a red filter, and then an image with a green filter. There is no way to get them matched up.

Georg

[TobiasLindemann]

Thank you Georg, you are surely right