IM: Math Utilities

IM - Imaging Libray

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Math Utilities
[Utilities]

Detailed Description

See im_color.h


Functions

template<class T, class TU>
T imZeroOrderDecimation (int width, int height, T *map, float xl, float yl, float box_width, float box_height, TU Dummy)
template<class T, class TU>
T imBilinearDecimation (int width, int height, T *map, float xl, float yl, float box_width, float box_height, TU Dummy)
template<class T>
T imZeroOrderInterpolation (int width, int height, T *map, float xl, float yl)
template<class T>
T imBilinearInterpolation (int width, int height, T *map, float xl, float yl)
template<class T, class TU>
T imBicubicInterpolation (int width, int height, T *map, float xl, float yl, TU Dummy)
template<class T>
void imMinMax (const T *map, int count, T &min, T &max)

Function Documentation

template<class T, class TU>
T imZeroOrderDecimation (  int  width,
int  height,
T *  map,
float  xl,
float  yl,
float  box_width,
float  box_height,
TU  Dummy
)  [inline]
 

Does Zero Order Decimation (Mean). 

00046 {
00047   int x0,x1,y0,y1;
00048   (void)Dummy;
00049 
00050   x0 = (int)floor(xl - box_width/2.0 - 0.5) + 1;
00051   y0 = (int)floor(yl - box_height/2.0 - 0.5) + 1;
00052   x1 = (int)floor(xl + box_width/2.0 - 0.5);
00053   y1 = (int)floor(yl + box_height/2.0 - 0.5);
00054 
00055   if (x0 == x1) x1++;
00056   if (y0 == y1) y1++;
00057 
00058   x0 = x0<0? 0: x0>width-1? width-1: x0;
00059   y0 = y0<0? 0: y0>height-1? height-1: y0;
00060   x1 = x1<0? 0: x1>width-1? width-1: x1;
00061   y1 = y1<0? 0: y1>height-1? height-1: y1;
00062 
00063   TU Value;
00064   int Count = 0;
00065 
00066   Value = 0;
00067 
00068   for (int y = y0; y <= y1; y++)
00069   {
00070     for (int x = x0; x <= x1; x++)
00071     {
00072       Value += map[y*width+x];
00073       Count++;
00074     }
00075   }
00076 
00077   if (Count == 0)
00078   {
00079     Value = 0;
00080     return (T)Value;
00081   }
00082 
00083   return (T)(Value/(float)Count);
00084 }

template<class T, class TU>
T imBilinearDecimation (  int  width,
int  height,
T *  map,
float  xl,
float  yl,
float  box_width,
float  box_height,
TU  Dummy
)  [inline]
 

Does Bilinear Decimation. 

00090 {
00091   int x0,x1,y0,y1;
00092   (void)Dummy;
00093 
00094   x0 = (int)floor(xl - box_width/2.0 - 0.5) + 1;
00095   y0 = (int)floor(yl - box_height/2.0 - 0.5) + 1;
00096   x1 = (int)floor(xl + box_width/2.0 - 0.5);
00097   y1 = (int)floor(yl + box_height/2.0 - 0.5);
00098 
00099   if (x0 == x1) x1++;
00100   if (y0 == y1) y1++;
00101 
00102   x0 = x0<0? 0: x0>width-1? width-1: x0;
00103   y0 = y0<0? 0: y0>height-1? height-1: y0;
00104   x1 = x1<0? 0: x1>width-1? width-1: x1;
00105   y1 = y1<0? 0: y1>height-1? height-1: y1;
00106 
00107   TU Value, LineValue;
00108   float LineNorm, Norm, dxr, dyr;
00109 
00110   Value = 0;
00111   Norm = 0;
00112 
00113   for (int y = y0; y <= y1; y++)
00114   {
00115     dyr = yl - (y+0.5f);
00116     if (dyr < 0) dyr *= -1;
00117 
00118     LineValue = 0;
00119     LineNorm = 0;
00120 
00121     for (int x = x0; x <= x1; x++)
00122     {
00123       dxr = xl - (x+0.5f);
00124       if (dxr < 0) dxr *= -1;
00125 
00126       LineValue += map[y*width+x] * dxr;
00127       LineNorm += dxr;
00128     }
00129 
00130     Value += LineValue * dyr;
00131     Norm += dyr * LineNorm;
00132   }
00133 
00134   if (Norm == 0)
00135   {
00136     Value = 0;
00137     return (T)Value;
00138   }
00139 
00140   return (T)(Value/Norm);
00141 }

template<class T>
T imZeroOrderInterpolation (  int  width,
int  height,
T *  map,
float  xl,
float  yl
)  [inline]
 

Does Zero Order Interpolation (Nearest Neighborhood). 

00147 {
00148   int x0 = (int)(xl-0.5f);
00149   int y0 = (int)(yl-0.5f);
00150   x0 = x0<0? 0: x0>width-1? width-1: x0;
00151   y0 = y0<0? 0: y0>height-1? height-1: y0;
00152   return map[y0*width + x0];
00153 }

template<class T>
T imBilinearInterpolation (  int  width,
int  height,
T *  map,
float  xl,
float  yl
)  [inline]
 

Does Bilinear Interpolation. 

00159 {
00160   int x0 = (int)(xl-0.5f);
00161   int y0 = (int)(yl-0.5f);
00162   int x1 = x0+1;
00163   int y1 = y0+1;
00164 
00165   float t = xl - (x0+0.5f);
00166   float u = yl - (y0+0.5f);
00167 
00168   x0 = x0<0? 0: x0>width-1? width-1: x0;
00169   y0 = y0<0? 0: y0>height-1? height-1: y0;
00170   x1 = x1<0? 0: x1>width-1? width-1: x1;
00171   y1 = y1<0? 0: y1>height-1? height-1: y1;
00172 
00173   T fll = map[y0*width + x0];
00174   T fhl = map[y0*width + x1];
00175   T flh = map[y1*width + x0];
00176   T fhh = map[y1*width + x1];
00177 
00178   return (T)((fhh - flh - fhl + fll) * u * t +
00179                          (fhl - fll) * t +
00180                          (flh - fll) * u +
00181                                 fll);
00182 }

template<class T, class TU>
T imBicubicInterpolation (  int  width,
int  height,
T *  map,
float  xl,
float  yl,
TU  Dummy
)  [inline]
 

Does Bicubic Interpolation. 

00188 {
00189   (void)Dummy;
00190 
00191   int x0 = (int)(xl-0.5f);
00192   int y0 = (int)(yl-0.5f);
00193   int x1 = x0-1; 
00194   int x2 = x0+2;
00195   int y1 = y0-1; 
00196   int y2 = y0+2;
00197 
00198   float t = xl - (x0+0.5f);
00199   float u = yl - (y0+0.5f);
00200 
00201   x1 = x1<0? 0: x1>width-1? width-1: x1;
00202   y1 = y1<0? 0: y1>height-1? height-1: y1;
00203   x2 = x2<0? 0: x2>width-1? width-1: x2;
00204   y2 = y2<0? 0: y2>height-1? height-1: y2;
00205 
00206   float CX[4], CY[4];
00207 
00208   // Optimize calculations
00209   {
00210     float x, x2, x3;
00211 
00212 #define C0 (-x3 + 2.0f*x2 - x)
00213 #define C1 ( x3 - 2.0f*x2 + 1.0f)
00214 #define C2 (-x3 + x2 + x)
00215 #define C3 ( x3 - x2)
00216 
00217     x = t;
00218     x2 = x*x; x3 = x2*x;
00219     CX[0] = C0; CX[1] = C1; CX[2] = C2; CX[3] = C3;
00220 
00221     x = u;
00222     x2 = x*x; x3 = x2*x;
00223     CY[0] = C0; CY[1] = C1; CY[2] = C2; CY[3] = C3;
00224   }
00225 
00226 #undef C0
00227 #undef C1
00228 #undef C2
00229 #undef C3
00230 
00231   TU LineValue, Value;
00232   float LineNorm, Norm;
00233 
00234   Value = 0;
00235   Norm = 0;
00236 
00237   for (int y = y1; y <= y2; y++)
00238   {
00239     LineValue = 0;
00240     LineNorm = 0;
00241 
00242     for (int x = x1; x <= x2; x++)
00243     {
00244       LineValue += map[y*width+x] * CX[x-x1];
00245       LineNorm += CX[x-x1];
00246     }
00247 
00248     Value += LineValue * CY[y-y1];
00249     Norm += CY[y-y1] * LineNorm;
00250   }
00251 
00252   if (Norm == 0)
00253   {
00254     Value = 0;
00255     return (T)Value;
00256   }
00257 
00258   Value = (Value/Norm);
00259 
00260   int size = sizeof(T); 
00261   if (size == 1)
00262     return (T)(Value<=0? 0: Value<=255? Value: 255);
00263   else
00264     return (T)(Value);
00265 }

template<class T>
void imMinMax (  const T *  map,
int  count,
T &  min,
T &  max
)  [inline]
 

Calculates minimum and maximum values. 

00271 {
00272   min = *map++;
00273   max = min;
00274   for (int i = 1; i < count; i++)
00275   {
00276     T value = *map++;
00277 
00278     if (value > max)
00279       max = value;
00280     else if (value < min)
00281       min = value;
00282   }
00283 }


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