Bead comparison template doesn't work

Got this error when trying to run the bead comparison probably since it is pretty outdated:
```
error: Must have one-to-one match between colors and channels (unless there is no more than 1 pro
cessed channel)
error: called from
    error at line 127 column 17
    ColorModel at line 86 column 17
    bead_comparison at line 28 column 4
```
I want to fix it and add a test.