/**
* vips_col_ab2h:
* @a: CIE a
* @b: CIE b
*
* Returns: Hue (degrees)
*/
double
vips_col_ab2h( double a, double b )
{
double h;
/* We have to get the right quadrant!
*/
if( a == 0 ) {
if( b < 0.0 )
h = 270;
else if( b == 0.0 )
h = 0;
else
h = 90;
}
else {
double t = atan( b / a );
if( a > 0.0 )
if( b < 0.0 )
h = VIPS_DEG( t + VIPS_PI * 2.0 );
else
h = VIPS_DEG( t );
else
h = VIPS_DEG( t + VIPS_PI );
}
return( h );
}
/**
* vips_col_ab2h:
* @a: CIE a
* @b: CIE b
*
* Returns: Hue (degrees)
*/
double
vips_col_ab2h( double a, double b )
{
double h;
#ifdef HAVE_ATAN2
h = VIPS_DEG( atan2( b, a ) );
if( h < 0.0 )
h += 360;
#else
/* We have to get the right quadrant!
*/
if( a == 0 ) {
if( b < 0.0 )
h = 270;
else if( b == 0.0 )
h = 0;
else
h = 90;
}
else {
double t = atan( b / a );
if( a > 0.0 )
if( b < 0.0 )
h = VIPS_DEG( t + VIPS_PI * 2.0 );
else
h = VIPS_DEG( t );
else
h = VIPS_DEG( t + VIPS_PI );
}
#endif
return( h );
}
void
vips_col_ab2Ch( float a, float b, float *C, float *h )
{
#ifdef HAVE_ATAN2
*h = VIPS_DEG( atan2( b, a ) );
if( *h < 0.0 )
*h += 360;
#else
*h = vips_col_ab2h( a, b );
#endif
#ifdef HAVE_HYPOT
*C = hypot( a, b );
#else
*C = sqrt( a * a + b * b );
#endif
}
