As i understand -
- target is determining color of object
- R, G and B CANNOT see object at same time , time between
two channels i 24mm/420mmsec=57msec . On other hand
distance between sensors 24mm is larger than distance between 2 objects, so if R channel is seeng object N - in this time G channel will see object N-x.

So - why You want to read sensor's outputs simultaneously?
You need some delay in data path for R an G data.

If i misunderstand -and R,G,B sensors see object simultaneously
(and then why You specify distances between sensors?),
then problem is how to read 3-sensors. You say sensor output is
something as freqwency - You need something like PCA - programmeble counter array.

Anyway - it seems my english is not good or Your explanation is
uncomplete.
regards