图像拉伸算法（线性拉伸、百分比拉伸、标准差拉伸）

qq_19816973

已于 2023-12-18 09:18:47 修改

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分类专栏：图像文章标签：算法图像处理

于 2023-12-18 09:13:57 首次发布

本文链接：https://blog.youkuaiyun.com/qq_19816973/article/details/135054648

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int PercentLinearTension(const T * poSrcData, T * poDstData, int nSizex, T smin, T smax, T dmin, T dmax, double percentMin, double percentMax)
{
   double s = smax - smin+ 0.5;
   int lowx = smin, lowy = smin + s*percentMin / 100;
   int highx = smax - s*percentMin / 100, highy = smax;
   double k = (double)(dmax - dmin) / (highx - lowy);
   double b = (double)(highx*dmin - lowy*dmax) / (highx - lowy);
   for (int i = 0; i < nSizex; i++)
   {
       if (poSrcData[i] == 0)
       {
           poDstData[i] = 0;
           continue;
       }

       if ( lowx <= poSrcData[i] && poSrcData[i] <= lowy)
       {
           poDstData[i] = 0;
           continue;
       }
       if (highx <= poSrcData[i] && poSrcData[i] <=highy)
       {
           poDstData[i] = 255;
           continue;
       }

       double at = k*poSrcData[i] + b;
       int tmp = 0;
       if (at - (int)at > 0.5)
           tmp = at + 0.5;
       else
           tmp = at - 0.5;

       if (tmp <= 0)
       {
           if (poSrcData[i] == 0)
               poDstData[i] = 0;
           else
               poDstData[i] = 0;//原来不是0的如果直接拉伸0将变为nodata
       }
       else if (tmp >= 255)
           poDstData[i] = 255;
       else
           poDstData[i] = (T)tmp;
   }
   return 0;
}

template<typename T>
int LinearTension(const T * poSrcData, T * poDstData, int nSizex, T smin, T smax, T dmin, T dmax)
{
   double k = (double)(dmax - dmin) / (smax - smin);
   double b = (double)(smax*dmin - smin*dmax) / (smax - smin);
for (int i = 0; i < nSizex; i++)
   {
       int tmp = k*poSrcData[i] + b;

       if (tmp <= 0)
       {
           if(poSrcData[i] == 0)
               poDstData[i] = 0;
           else
               poDstData[i] = 1;
       }
       else if (tmp >= 255)
           poDstData[i] = 255;
       else
           poDstData[i] = (T)tmp;
   }
   return 0;
}

template<typename T>
int StandardDeviationTension(const T * poSrcData, T * poDstData, int nSizex,
T smin, T smax, T dmin, T dmax,
double StandardDeviation, double avg, int Kn)
{

//Kn 倍数，一般设为2.5
double ucMax = avg + Kn * StandardDeviation;
double ucMin = avg - Kn * StandardDeviation;

double k = (double)(dmax - dmin) / (ucMax - ucMin);
double b = (double)(ucMax*dmin - ucMin*dmax) / (ucMax - ucMin);

   if (ucMin <= 0)
   {
       ucMin = 0;
   }
   for (int i = 0; i < nSizex; i++)
   {
       if (poSrcData[i] == 0)
       {
           poDstData[i] = 0;
           continue;
       }
       if (poSrcData[i] <= ucMin)
       {
           poDstData[i] = 0;
           continue;
       }
       else if (poSrcData[i] >= ucMax)
       {
           poDstData[i] = 255;
           continue;
       }

int tmp = k*poSrcData[i] + b;

       if (tmp <= 0)
       {
           if (poSrcData[i] == 0)
               poDstData[i] = 0;
           else
               poDstData[i] = 1;
       }
       else if (tmp >= 255)
           poDstData[i] = 255;
       else
           poDstData[i] = (T)tmp;
   }
   return 0;
}