使用 cvtColor 转换单一颜色

问题描述

我有一种颜色想要转换为不同的颜色空间.是否可以直接在 cv::Vec3f 上使用 cvtColor 而无需创建 1x1 cv::Mat 并用该像素填充它，使用cvtColor 在 cv::Mat 上，然后从输出中获取唯一的像素?我尝试了以下方法，但似乎不喜欢传递向量.

I have a color that I want to convert to a different color space. Is it possible to use cvtColor on a cv::Vec3f directly without creating a 1x1 cv::Mat and populating it with that pixel, using cvtColor on the cv::Mat, then getting the only pixel out of the output? I have tried the following, but it doesn't seem to like getting passed a vector.

有什么建议吗?

#include <iostream>

#include <opencv2/opencv.hpp>

int main(int, char*[])
{
    cv::Vec3f hsv;
    hsv[0] = .9;
    hsv[1] = .8;
    hsv[2] = .7;

    std::cout << "HSV: " << hsv << std::endl;

    cv::Vec3b bgr;
    cvtColor(hsv, bgr, CV_HSV2BGR); // OpenCV Error: Assertion failed (scn == 3 && (dcn == 3 || dcn == 4) && (depth == CV_8U || depth == CV_32F)) in cvtColor

    std::cout << "BGR: " << bgr << std::endl;

    return EXIT_SUCCESS;
}

我也试过这个，但得到一个不同的错误:

I also tried this, but get a different error:

#include <iostream>

#include <opencv2/opencv.hpp>

int main(int, char*[])
{
    cv::Mat_<cv::Vec3f> hsv(cv::Vec3f(0.7, 0.7, 0.8));

    std::cout << "HSV: " << hsv << std::endl;

    cv::Mat_<cv::Vec3b> bgr;

    cvtColor(hsv, bgr, CV_HSV2BGR); // OpenCV Error: Assertion failed (!fixedType() || ((Mat*)obj)->type() == mtype) in create

    std::cout << "BGR: " << bgr << std::endl;

    return EXIT_SUCCESS;
}

推荐答案

您的第二种方法是正确的，但是您在 cvtColor 中有不同类型的源和目标，这会导致错误.

Your second approach is correct, but you have source and destination of different types in cvtColor, and that causes the error.

确保 hsv 和 bgr 的类型相同，CV_32F 在这里:

Be sure to have both hsv and bgr of the same type, CV_32F here:

#include <opencv2/opencv.hpp>
#include <iostream>

int main()
{
    cv::Mat3f hsv(cv::Vec3f(0.7, 0.7, 0.8));

    std::cout << "HSV: " << hsv << std::endl;

    cv::Mat3f bgr;
    cvtColor(hsv, bgr, CV_HSV2BGR);

    std::cout << "BGR: " << bgr << std::endl;

    return 0;
}

为了简洁起见，您可以使用 Mat3f.这只是一个类型定义:

---

You can use Mat3f for brevity. It's just a typedef:

typedef Mat_<Vec3f> Mat3f;

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