如何使用Scalar类指定颜色

Question

我不知道如何在下面发布的方法中使用Scalar类来指定颜色？

Features2d.drawKeypoints(mKeyPoints_0, mKeyPoints_0, outImage, Scalar color, Features2d.DRAW_RICH_KEYPOINTS);

Answer 1

用法Scalar指定颜色,取决于该Mat类型.尝试Red在灰度级上存储/绘制颜色Mat将失败.

• 类型CV_8UC1- 灰度图像

  //8 bits per pixel and so range of [0:255]. 
  Scalar color = new Scalar( 255 )
  //For type: 16UC1, range of [0:65535]. For 32FC1 range is [0.0f:1.0f] 
  

• 类型CV_8UC3- 3通道彩色图像

  // BLUE: color ordering as BGR
  Scalar color = new Scalar( 255, 0, 0 ) 
  

• 类型CV_8UC4- 具有透明度的彩色图像

  //Transparent GREEN: BGRA with alpha range - [0 : 255]
  Scalar color = new Scalar( 0, 255, 0, 128 ) 
  

在问题中,第一个参数drawKeyPoints应该是您的源图像(Mat)而不是关键点.代码将编译因为MatOfKeyPoint派生自Mat