c++ - 实现 RGBtoHSV C++，错误的 H 输出

Question

我正在尝试在 HSV 维度中执行 Sobel 运算符(我的向导告诉我在 HSV 中执行此操作，但我不明白为什么它在 HSV 上比在 RGB 上工作得更好)。我构建了一个从 RGB 转换为 HSV 的函数。虽然我在 C++ 方面的知识一般，但我对图像处理感到困惑，因此我试图使代码尽可能简单，这意味着我不关心(在这个阶段)时间和空间。从我在灰度级 bmp 照片中得到的结果来看，我的 V 和 S 似乎很好，但我的 H 看起来很乱码。我在这里有 2 个问题:1. 与源照片相比，灰度级别的普通 H 照片应该看起来如何？2.我的代码哪里错了:

   void RGBtoHSV(unsigned char image[][NUMBER_OF_COLUMNS][NUMBER_OF_COLORS],
float Him[][NUMBER_OF_COLUMNS],
float Vim[][NUMBER_OF_COLUMNS], 
float Sim[][NUMBER_OF_COLUMNS])
{

double Rn, Gn, Bn;

double   C;
double H, S, V;

for (int row = 0; row < NUMBER_OF_ROWS; row++)
{
    for (int column = 0; column < NUMBER_OF_COLUMNS; column++)
    {
        Rn = (1.0*image[row][column][R]) / 255;
        Gn = (1.0*image[row][column][G] )/ 255;
        Bn = (1.0*image[row][column][B] )/ 255;

        //double RGBn[3] = { Rn, Gn, Bn };

        double max = Rn;
        if (max < Gn) max = Gn;
        if (max < Bn) max = Bn;
        double min = Rn;
        if (min > Gn) min = Gn;
        if (min > Bn) min = Bn;

        C = max - min;

        H = 0;
        if (max==0)
        {
            S = 0;
            H = -1; //undifined;
            V = max;
        }
        else
        {

        /*  if (max == Rn)
                H = (60.0* ((int)((Gn - Bn) / C) % 6));
            else if (max == Gn)
                H = 60.0*( (Bn - Rn)/C + 2);
            else
                H = 60.0*( (Rn - Gn)/C + 4);
            */

            if (max == Rn)
                H = (   60.0* ( (Gn - Bn) / C) )   ;
            else if (max == Gn)
                H = 60.0*((Bn - Rn) / C + 2);
            else
                H = 60.0*((Rn - Gn) / C + 4);

            V = max; //AKA lightness
            S = C / max; //saturation 
        }


        while (H < 0) 
            H += 360;
        while (H>360) 
            H -= 360;

        Him[row][column] = (float)H;

        Vim[row][column] = (float)V;
        Sim[row][column] = (float)S;
    }
}
}

还有我的 hsvtorgb :

void HSVtoRGB(unsigned char image[][NUMBER_OF_COLUMNS][NUMBER_OF_COLORS],
float Him[][NUMBER_OF_COLUMNS],
float Vim[][NUMBER_OF_COLUMNS],
float Sim[][NUMBER_OF_COLUMNS])
{

double R1, G1, B1;

double   C;
double   V;
double S;
double H;
int Htag;
double Htag2;
double x;
double m;

for (int row = 0; row < NUMBER_OF_ROWS; row++)
{
    for (int column = 0; column < NUMBER_OF_COLUMNS; column++)
    {
        H = (double)Him[row][column];
        S = (double)Sim[row][column];
        V = (double)Vim[row][column];


        C = V*S;

        Htag = (int) (H / 60.0);
        Htag2 = H/ 60.0;


        //x = C*(1 - abs(Htag % 2 - 1));
        double tmp1 = fmod(Htag2, 2);
        double temp=(1 - abs(tmp1 - 1));
        x = C*temp;
        //switch (Htag)
        switch (Htag)
        {
        case 0 : 
            R1 = C;
            G1 = x;
            B1 = 0;
            break;
        case 1:
            R1 = x;
            G1 = C;
            B1 = 0;
            break;
        case 2:
            R1 = 0;
            G1 = C;
            B1 = x;
            break;
        case 3:
            R1 = 0;
            G1 = x;
            B1 = C;
            break;
        case 4:
            R1 = x;
            G1 = 0;
            B1 = C;
            break;
        case 5:
            R1 = C;
            G1 = 0;
            B1 = x;
            break;
        default:
            R1 = 0;
            G1 = 0;
            B1 = 0;
            break;

        }


        m = V - C;
   //this is also good change I found
        //image[row][column][R] = unsigned char( (R1 + m)*255);
        //image[row][column][G] = unsigned char( (G1 + m)*255);
        //image[row][column][B] = unsigned char( (B1 + m)*255);

        image[row][column][R] = round((R1 + m) * 255);
        image[row][column][G] = round((G1 + m) * 255);
        image[row][column][B] = round((B1 + m) * 255);



            }
      }
   }


   void HSVfloattoGrayconvert(unsigned char grayimage[NUMBER_OF_ROWS]        [NUMBER_OF_COLUMNS], float hsvimage[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS], char hsv)
  {
//grayimage , flaotimage , h/s/v
   float factor;
if (hsv == 'h' || hsv == 'H') factor = (float) 1 / 360;
else factor = 1;
for (int row = 0; row < NUMBER_OF_ROWS; row++)
{
    for (int column = 0; column < NUMBER_OF_COLUMNS; column++)
    {
        grayimage[row][column] = (unsigned char) (0.5f + 255.0f * (float)hsvimage[row][column] / factor);
          }
      }
 }

和我的主要:

 unsigned char ColorImage1[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS]   [NUMBER_OF_COLORS];
float Himage[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];
float Vimage[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];
float Simage[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];

 unsigned char ColorImage2[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS]   [NUMBER_OF_COLORS];

unsigned char HimageGray[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];
unsigned char VimageGray[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];
unsigned char SimageGray[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];

unsigned char HAfterSobel[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];
unsigned char VAfterSobel[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];
unsigned char SAfterSobal[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS];

   unsigned char HSVcolorAfterSobal[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS][NUMBER_OF_COLORS];

unsigned char RGBAfterSobal[NUMBER_OF_ROWS][NUMBER_OF_COLUMNS][NUMBER_OF_COLORS];


int KernelX[3][3] = { 
{-1,0,+1}, {-2,0,2}, {-1,0,1 }
};

  int KernelY[3][3] = {
   {-1,-2,-1}, {0,0,0}, {1,2,1}
  };

  void main()
{

//work
LoadBgrImageFromTrueColorBmpFile(ColorImage1, "P22A.bmp");

// add noise
AddSaltAndPepperNoiseRGB(ColorImage1, 350, 255);
StoreBgrImageAsTrueColorBmpFile(ColorImage1, "saltandpepper.bmp");
AddGaussNoiseCPPstileRGB(ColorImage1, 0.0, 1.0);
StoreBgrImageAsTrueColorBmpFile(ColorImage1, "Saltandgauss.bmp");

//saves hsv in float array 
RGBtoHSV(ColorImage1, Himage, Vimage, Simage); 

//saves hsv float arrays in unsigned char arrays
HSVfloattoGrayconvert(HimageGray, Himage, 'h');
HSVfloattoGrayconvert(VimageGray, Vimage, 'v');
HSVfloattoGrayconvert(SimageGray, Simage, 's');


StoreGrayImageAsGrayBmpFile(HimageGray, "P22H.bmp");
StoreGrayImageAsGrayBmpFile(VimageGray, "P22V.bmp");
StoreGrayImageAsGrayBmpFile(SimageGray, "P22S.bmp");

    WaitForUserPressKey();

  }

编辑:更改代码 + 添加方程式来源:来源:方程式:

1. http://www.rapidtables.com/convert/color/hsv-to-rgb.htm
2. http://www.rapidtables.com/convert/color/rgb-to-hsv.htm

编辑3:听@gpasch建议和使用better reference并删除 mod6 我现在可以恢复 RGB 原始照片了!!!但不幸的是，现在我的灰度 H 照片比以前更加困惑。我将编辑代码，以便它包含有关我如何保存 H 灰度照片的更多信息。

Answer 1

这就是浏览垃圾网站的危险；我建议如下:

https://www.cs.rit.edu/~ncs/color/t_convert.html

那个 mod 6 在那里看起来很可疑。

您还需要确保了解 H 的单位是从 0 到 360 的度数；如果您的过滤器需要 0..1，则您有更改。