浮点异常 C

Question

我在测试以下功能时不断收到此错误。它应该标准化包含颜色 0 到 255 像素的图像的值。我找到了最小值和最大值，将它们更改为 0 和 255，然后相应地更改所有中间值以适应之前相同的差异比率：

void normalize( uint8_t array[],
        unsigned int cols,
        unsigned int rows )
{
  uint8_t minValue = 255;
  uint8_t maxValue = 0; 

  for (int i = 0; i < cols*rows ; ++i)
    {
      if(array[i] < minValue) minValue = array[i];
    }

  for (int i = 0; i < cols*rows; ++i)
    {
      if(array[i] < maxValue) maxValue = array[i];
    }

  int difference1 = maxValue - minValue;

  uint8_t ratios[cols*rows];

  for (int i = 0; i < cols*rows ; ++i){
    ratios[i] = 0;
  }

  //find the ratios
  for (int i = 0; i < cols*rows ; ++i){
    ratios[i] = (array[i] / difference1) - 1;
  }

  for (int i = 0; i < cols*rows ; ++i){

    if(array[i] == minValue){
      array[i] = 0;
    }else if(array[i] == maxValue){
      array[i] = 255;
    }else{
      array[i] = round(ratios[i] * 255);
    }
  }
}

Answer 1

`max.计算错误

尽管代码应该如下所示，但这还不是全部。

// if(array[i] < maxValue) maxValue = array[i];
if(array[i] > maxValue) maxValue = array[i];

如果所有像素的颜色相同 (difference1 == 0)，代码应该仍然有效。在这种情况下，一个简单的解决方案是不理会 array[]。

int difference1 = maxValue - minValue;
if (difference1 > 0) {
  uint8_t ratios[cols*rows];
  ...
      array[i] = round(ratios[i] * 255);
    }
  }
}

Answer 2

这样的说法正确吗？

void normalize( uint8_t 数组[], 无符号整数列，无符号整数行） {

//each pixel is rounded by 255 * (index-lowest_pixel_val_in_array) divided by ( highest value pixel minus lowest value pixel)

 // your code here
uint8_t minValue = 255; //255 means WHITE
uint8_t maxValue = 0;  // 0 MEANS BLACK 

for (int i = 0; i < cols*rows ; ++i) //PREINCREMENT means if i= 1 and j=++i=2/
{
  if(array[i] < minValue) 
minValue = array[i]; //make minimum value the array

  if(array[i]  > maxValue) 
 maxValue = array[i]; //make maximum value for array
}

int difference = maxValue - minValue; //the difference is maximum - minimum

// uint8_t 比率[列*行]; //改变把这个放在里面

if(difference > 0) //ENSURE MAX != MIN
{ 
uint8_t ratios[cols*rows]; //CHANGED PUT THIS INSIDE 
for (int i = 0; i < cols*rows ; ++i) //PREINCREMENT means if i= 1 and j=++i. j becomes 2 but for i++ j wuld be 1
{
      ratios[i] = 0; //SET IT 0 INTIALLY. 
      ratios[i] = (array[i] / difference) - 1; //subtract 1st pixel and CALCULATE RATIOS


      if(array[i] == minValue)
          {
          array[i] = 0; //lightest becomes darkest
          }

      else if(array[i] == maxValue)
      {
          array[i] = 255; //darkest becomes lightest
          }

      else
      {
          array[i] = round(ratios[i] * 255); //ROUND THE PIXEL
          }
}
}

}

浮点异常 C

Floating Point Exception C

c

floating-point

exception