b0 = ReadByte #unsigned
b1 = ReadByte #unsigned
b2 = ReadByte #unsigned
b3 = ReadByte #unsigned
f0=(float)b0/255.f;
f1=(float)b1/255.f;
f2=(float)b2/255.f; 
f3=(float)b3/255.f;
f3=1.f - f3;
U = f0+(f2/32.f);
V = f1+(f3/32.f);