Jay suggested:

>If the goal is to take just the high byte of the 2-byte value, you
>should do an integer divide by 256, which will yield an integer value
>from 0 to 255.

Jay,

Good call. Changed the floating point divide (from legacy code) and 
went back to integer with 256 and it works fine.

Unfortunately I am still struggling with the CMYK function returning 
erroneous values. Also tried Brian's @test(0) without any difference.

Thanks.

Ken