标签：opencv3-0 c opencv

该文档似乎没有解释HSV-> BGR转换的预期输入范围.这是一些示例代码,我试图在将其转换为HSV后恢复原始BGR值.有谁知道预期的缩放比例？

#include <iostream>

#include <opencv2/opencv.hpp>

cv::Vec3b HSVtoBGR(const cv::Vec3f& hsv)
{
    cv::Vec3f hsvAdjusted = hsv; // If we use this directly, the output is (0,0,1) which is very wrong
    //hsvAdjusted[0] *= 360.; // If we do this to bring all of the values into the range (0,1), the output is (0,1,0), which is also very wrong

    // If we do this to bring all of the values into the range (0,255), the output is (0,0,200), which is still very wrong
    hsvAdjusted[1] *= 255./360.;
    hsvAdjusted[1] *= 255.;
    hsvAdjusted[2] *= 255.;

    cv::Mat_<cv::Vec3f> hsvMat(hsvAdjusted);

    cv::Mat_<cv::Vec3f> bgrMat;

    cv::cvtColor(hsvMat, bgrMat, CV_HSV2BGR);

    cv::Vec3b bgr = static_cast<cv::Vec3b>(bgrMat(0,0));
    return bgr;
}

/** Input 0 <= B <= 255, 0 <= G <= 255, 0 <= R <= 255
  * Output 0 <= H <= 360, 0 <= S <= 1, 0 <= V <= 1  */
cv::Vec3f BGRtoHSV(const cv::Vec3b& bgr)
{
    cv::Mat3f bgrMat(static_cast<cv::Vec3f>(bgr));

    bgrMat *= 1./255.;

    cv::Mat3f hsvMat;
    cv::cvtColor(bgrMat, hsvMat, CV_BGR2HSV);

    cv::Vec3f hsv = hsvMat(0,0);

    return hsv;
}

int main()
{
    // Create a BGR color
    cv::Vec3b bgr(5, 100, 200);
    std::cout << "bgr: " << bgr << std::endl;

    // Convert BGR to HSV
    cv::Vec3f hsv = BGRtoHSV(bgr);
    std::cout << "hsv: " << hsv << std::endl; // outputs // (29.23, .976, .7843), which seems correct

    // Convert back from HSV to BGR
    cv::Vec3b bgr2 = HSVtoBGR(hsv);
    std::cout << "bgr2: " << bgr2 << std::endl;

    return 0;
}

解决方法:

HSVtoBGR函数中存在一些缩放问题.

转换后需要将结果乘以255,而不是之前.请记住,对于CV_32F和CV_8U类型的Mat,会发生不同的转换.

这应该按预期工作：

cv::Vec3b HSVtoBGR(const cv::Vec3f& hsv)
{
    cv::Mat_<cv::Vec3f> hsvMat(hsv);
    cv::Mat_<cv::Vec3f> bgrMat;

    cv::cvtColor(hsvMat, bgrMat, CV_HSV2BGR);

    bgrMat *= 255; // Upscale after conversion

    // Conversion to Vec3b is handled by OpenCV, no need to static_cast
    return bgrMat(0);
}

标签：opencv3-0,c,opencv
来源： https://codeday.me/bug/20191002/1844017.html

本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享；
2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关；
3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关；
4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除；
5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。