为什么 openCV 的 fastNlMeansDenoisingColored() 给出错误？

我是菜鸟openCV概念，所以如果我的问题很愚蠢，请原谅我。实际上我正在尝试应用Photo.fastNlMeansDenoisingColored()方法，但我不明白为什么它会给出这样的错误。

Code:

Mat tmp = new Mat (bitmap.getWidth(), bitmap.getHeight(), CvType.CV_8UC1);

            Utils.bitmapToMat(bitmap, tmp);

            Photo.fastNlMeansDenoisingColored(tmp,tmp, 10, 10, 7, 21);


            Utils.matToBitmap(tmp,bitmap);

Error:

CvException [org.opencv.core.CvException: cv::Exception: /hdd2/buildbot/slaves/slave_ardbeg1/50-SDK/opencv/modules/photo/src/denoising.cpp:91: error: (-5) Type of input image should be CV_8UC3! in function void cv::fastNlMeansDenoisingColored(cv::InputArray, cv::OutputArray, float, float, int, int)
]
    at org.opencv.photo.Photo.fastNlMeansDenoisingColored_0(Native Method)
    at org.opencv.photo.Photo.fastNlMeansDenoisingColored(Photo.java:118)
    at opengl.community.myopencvexample.MainActivity$3.onClick(MainActivity.java:83)
    at android.view.View.performClick(View.java:4478)
    at android.view.View$PerformClick.run(View.java:18698)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:149)
    at android.app.ActivityThread.main(ActivityThread.java:5257)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
    at dalvik.system.NativeStart.main(Native Method)

下载本机库并将它们放入你的main/jniLibs目录。