C/C++ :: Separate Byte Of Array Into Nibble For New Array

How can I separate byte array and put nibbles in a new array?

when I try following:

byte in[]={0xab,0x11,0x22,0x33,0xbb}; 
byte out[10];  
void seperatebyte(byte* input, byte* output) {  
  for(int i = 0;i<sizeof(input);i++)  {   
        output[i*2]  = (input[i] >> 4) & 0xf;
        output[(i*2)+1]  = input[i] & 0xf;
     }  
}  

seperatebyte(in,out); //gives output of  

10 11 1 1 184 1 184 0 0 0

I expect 10 11 1 1 2 2 3 3 11 11