python - HSV 值是否作为 VSH 存储在 numpy 数组中？

Question

由于 RGB 存储为 BGR，所以在 HSV 的情况下是否也会发生同样的情况？

我正在做一个项目，我从网络摄像头获取输入并将其转换为 HSV 颜色，以跟踪特定颜色的对象。

Answer 1

没有。它是 HSV 模式。

阅读下面的代码及其在示例图像上的运行。

int main()
{
    // Load your Red colored image
    cv::Mat frame = imread("test.png");

    // Split each channel
    cv::Mat rgbChannels[3];
    cv::split(frame, rgbChannels);
    cv::imshow("RGB", frame);

    // Check value of your Red, Blue and Green Channel
    double minVal, maxVal;
    // Note: Blue is first channel
    cv::minMaxLoc(rgbChannels[0], &minVal, &maxVal);
    std::cout << "Blue: Min = " << minVal << ", Max = " << maxVal << std::endl;
    cv::minMaxLoc(rgbChannels[1], &minVal, &maxVal);
    std::cout << "Green: Min = " << minVal << ", Max = " << maxVal << std::endl;
    cv::minMaxLoc(rgbChannels[2], &minVal, &maxVal);
    std::cout << "Red: Min = " << minVal << ", Max = " << maxVal << std::endl;

    std::cout << "*******************************" << std::endl;

    cv::Mat hsv;
    cv::Mat hsvChannels[3];
    // Convert BGR image to HSV. Dont use CV_RGB2HSV.
    cv::cvtColor(frame, hsv, CV_BGR2HSV);

    // Split each channel
    cv::split(hsv, hsvChannels);

    // **Display HSV image: Note: When displaying opencv does not display image as Red image**
    // This is because imshow will just take first channel which is hue and treat it as Blue, second channel as 
    // Green, and last channel as Red.
    cv::imshow("HSV", hsv);
    cv::minMaxLoc(hsvChannels[0], &minVal, &maxVal);
    std::cout << "Hue: Min = " << minVal << ", Max = " << maxVal << std::endl;
    cv::minMaxLoc(hsvChannels[1], &minVal, &maxVal);
    std::cout << "Saturation: Min = " << minVal << ", Max = " << maxVal << std::endl;
    cv::minMaxLoc(hsvChannels[2], &minVal, &maxVal);
    std::cout << "Value: Min = " << minVal << ", Max = " << maxVal << std::endl;
    waitKey(0);
    return 0;
}

输出:-

Blue: Min = 36, Max = 36
Green: Min = 28, Max = 28
Red: Min = 237, Max = 237
*******************************
Hue: Min = 179, Max = 179
Saturation: Min = 225, Max = 225
Value: Min = 237, Max = 237

输出说明 使用这个 tool ，RGB 值 (237, 28, 36) 映射到 HSV (358, 88.2, 92.9)。由于 HUE 的范围从 0 到 359，因此该值跨越 1 字节界限，仅允许 256 个值。在 opencv 中 HUE 除以 2 范围从 [0,179] 以使用更少的内存。色调值 358 除以 2 映射到第一个 channel 179。此外，饱和度和值只是标准化为 0-255 的比例。因此，正如您所见，饱和度映射到第二个 channel ，值映射到第三个 channel 。