android opencv RGB转HSV

Question

如何在opencv for android中将rgb转换为hsv并让hsv显示在屏幕上？

using namespace std;
using namespace cv;

extern "C" {
JNIEXPORT void JNICALL Java_org_opencv_samples_tutorial3_Sample3View_FindFeatures(JNIEnv* env, jobject thiz, jint width, jint height, jbyteArray yuv, jintArray bgra)
{
    jbyte* _yuv  = env->GetByteArrayElements(yuv, 0);
    jint*  _bgra = env->GetIntArrayElements(bgra, 0);

    Mat myuv(height + height/2, width, CV_8UC1, (unsigned char *)_yuv);
    Mat mbgra(height, width, CV_8UC4, (unsigned char *)_bgra);
    Mat mgray(height, width, CV_8UC1, (unsigned char *)_yuv);


    //Please make attention about BGRA byte order
    //ARGB stored in java as int array becomes BGRA at native level
    cvtColor(myuv, mbgra, CV_YUV420sp2BGR, 4);





    env->ReleaseIntArrayElements(bgra, _bgra, 0);
    env->ReleaseByteArrayElements(yuv, _yuv, 0);
}

}

上面的代码从相机获取输入yuv并转换为rgb。我知道我需要使用 cvtColor 函数从 rgb 转换为 hsv，但是 hsv 的 Mat 应该具有哪些参数？以及如何让它显示而不是rgb

Answer 1

如果您想将 RGB Mat 图像转换为 HSV 颜色空间，您可以这样做:

Imgproc.cvtColor(src, dst, Imgproc.COLOR_RGB2HSV, 3); //3 is HSV Channel

在 Android 屏幕上显示它之前，您需要将 HSV 从 3 channel 转换为 4 channel ，因为 Android 无法在 3 channel 中显示 Mat。请参阅this了解更多信息。代码如下:

Imgproc.cvtColor(dst, src, Imgproc.COLOR_HSV2RGBA, 4); // 4 is RGBA Channel