16 bit color formats

http://forums.creativecow.net/thread/2/940078

In adobe after effects:

#define PF_MAX_CHAN8			255
#define PF_HALF_CHAN8			128
#define PF_MAX_CHAN16			32768
#define PF_HALF_CHAN16			16384
#define CONVERT8TO16(A)		( (((long)(A) * PF_MAX_CHAN16) + PF_HALF_CHAN8) / PF_MAX_CHAN8 )