Recent colorspace conversion change

#include <stdio.h>

#if !defined(QuantumDepth)
#  define QuantumDepth  16
#endif

#if (QuantumDepth == 8)
#  define MaxMap  255U
#  define MaxMapFloat 255.0f
#  define MaxMapDouble 255.0
#elif (QuantumDepth == 16)
#  define MaxMap 65535U
#  define MaxMapFloat 65535.0f
#  define MaxMapDouble 65535.0
#elif (QuantumDepth == 32)
#  define MaxMap 65535U
#  define MaxMapFloat 65535.0f
#  define MaxMapDouble 65535.0
#endif

int main(int argc, char* argv[])
{
  (void) argc;
  (void) argv;

  float int_round = ((MaxMap+1)/2);
  float float_round = (((float) MaxMap+1)/2);

  printf("int round = %g, float round = %g\n",
         int_round, float_round);

  return 0;
}

% gcc -DQuantumDepth=8 -Wall -O3 -o rounding rounding.c
% ./rounding                                           
int round = 128, float round = 128
% gcc -DQuantumDepth=16 -Wall -O3 -o rounding rounding.c
% ./rounding                                            
int round = 32768, float round = 32768
% gcc -DQuantumDepth=32 -Wall -O3 -o rounding rounding.c
% ./rounding                                            
int round = 32768, float round = 32768