OpenCV中的线性颜色渐变 [英] Linear Color Gradient in openCV

问题描述

我想创建两种颜色的渐变，如Photoshop。输入两种颜色的
r，g，b，结果将是渐变的Mat。我试过它至少5个小时，我无法找到确切的效果，从Photoshop。
我试图创建自己的公式（因为我不能在网上找到任何），通过将RGB更改为HSV，然后将相对于总行数的hue的差异添加到Mat的每行并且还降低强度到图像的中心，然后再次增加。

i am trying to create gradient of two colors like Photoshop. r,g,b of two colors is input and result will be the Mat of gradient. I tried it like for 5 hours at least and i could not find exact effect as of the Photoshop. I tried to create my own formula (as i could not find any on the web), by changing RGB to HSV and then adding the difference of hue, with respect to the total number of rows, to each row of Mat with and also decreasing intensity to the center of image and then increasing it again. The code is self explanatory.

此外，如果任何人可以告诉我创建渐变的确切公式，这将是非常有帮助的。

Additionally if anyone can tell me the exact formula for creating a gradient it will be really helpful.

这里是Photoshop渐变的样子

here is how Photoshop gradient looks like

这是我从我的代码

 int r1, g1, b1, r2, g2, b2;

 r1 = 255;
 g1 = 0;
 b1 = 0;
 r2 = 0;
 g2 = 255;
 b2 = 0;

 Mat input = imread("img.jpg");
 Mat color1(input.size(), input.type());
 Mat color2(input.size(), input.type());

 vector<Mat> bgr1;
 vector<Mat> bgr2;

 split(color1, bgr1);
 bgr1[0] = b1;
 bgr1[1] = g1;
 bgr1[2] = r1;
 merge(bgr1, color1);

 split(color2, bgr2);
 bgr2[0] = b2;
 bgr2[1] = g2;
 bgr2[2] = r2;
 merge(bgr2, color2);

 vector<Mat> hls1;
 vector<Mat> hls2;

 cvtColor(color1, color1, CV_BGRA2BGR);
 cvtColor(color1, color1, CV_BGR2HSV);
 split(color1, hls1);

 cvtColor(color2, color2, CV_BGRA2BGR);
 cvtColor(color2, color2, CV_BGR2HSV);
 split(color2, hls2);

 double h1 = hls1[0].at<uchar>(0, 0);
 double h2 = hls2[0].at<uchar>(0, 0);
 double dif = (h2 - h1) / input.rows;
 double h = h1;

 double halfL = 255 / 2;
 double halfR = input.rows / 2;
 double ldif = halfL / halfR;
 double l = 255;
 bool isHalf = false;

 for (int i = 0; i < input.rows; i++)
 {
  for (int j = 0; j < input.cols; j++)
  {
   hls1[0].at<uchar>(i, j) = h;
   hls1[2].at<uchar>(i, j) = l;
  }


  if (isHalf == false){
   l -= ldif;
  }
  else{
   l += ldif;
  }

  if (i < input.rows * 0.40)
  {
   h += dif * 0.40;
  }
  else if (i < input.rows * 0.60)
  {
   h += dif * 3;
  }
  else
  {
   h += dif * 0.40;
  }

  if (i >= input.rows / 2)
  {
   isHalf = true;
  }
 }

 merge(hls1, color1);
 merge(hls2, color2);

 cvtColor(color1, color1, CV_HSV2BGR);
 cvtColor(color1, color1, CV_BGR2BGRA);

 cvtColor(color2, color2, CV_HSV2BGR);
 cvtColor(color2, color2, CV_BGR2BGRA);

 namedWindow("Color1", cv::WINDOW_NORMAL);
 resizeWindow("Color1", color1.size().width / 2, color1.size().height / 2);
 imshow("Color1", color1);

 waitKey(0);
 destroyAllWindows();
 system("pause");

推荐答案

>

这似乎是一个非常复杂的代码，应该更容易。
我会这样做。

It seems to be a really complex code for something that should be easier. I would do something like that.

int taille = 500;    
Mat image(taille,taille,CV_8UC3);
for(int y = 0; y < taille; y++){
   Vec3b val;
   val[0] = 0; val[1] = (y*255)/taille; val[2] = (taille-y)*255/taille;
   for(int x = 0; x < taille; x++)
      image.at<Vec3b>(y,x) = val;
}

在Micka的建议，我添加一个结果的图片taille = 400;

On Micka's advice, I add a picture of the result with taille = 400;

这篇关于OpenCV中的线性颜色渐变的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！