使用mixChannels函数(opencv)时，出现“致命信号11 (SIGSEGV)，代码1”

Question

我尝试用Android JNI和OpenCV开发应用程序，得到了一个可怕的错误:libc:致命信号11 (SIGSEGV)，代码1，tid 28694中的错误地址0xfffffffc。

我按照这篇文章来实现这个算法，当我在Visual studio 2015上运行它时，它工作得很好。但是当我尝试在Android JNI上实现它时，它出现了以下错误。

这是我的代码：

#include <jni.h>
#include <opencv2/opencv.hpp>


using namespace std;
using namespace cv;

extern "C" {
JNIEXPORT void JNICALL
Java_com_noah_demojniexp_MainActivity_autofix(JNIEnv *env, jobject instance, jlong matAddr,
                                          jlong dstAddr, jfloat clipHistPercent) {
Mat &src = *((Mat *) matAddr);
Mat &dst = *((Mat *) dstAddr);

CV_Assert(clipHistPercent >= 0);
CV_Assert((src.type() == CV_8UC1) || (src.type() == CV_8UC3) || (src.type() == CV_8UC4));

int histSize = 256;
float alpha, beta;
double minGray = 0, maxGray = 0;

//to calculate grayscale histogram
Mat gray;
if (src.type() == CV_8UC1) gray = src;
else if (src.type() == CV_8UC3) cvtColor(src, gray, CV_BGR2GRAY);
else if (src.type() == CV_8UC4) cvtColor(src, gray, CV_BGRA2GRAY);
if (clipHistPercent == 0)
{
    // keep full available range
    minMaxLoc(gray, &minGray, &maxGray);
}
else
{
    Mat hist; //the grayscale histogram

    float range[] = { 0, 256 };
    const float* histRange = { range };
    bool uniform = true;
    bool accumulate = false;
    calcHist(&gray, 1, 0, Mat (), hist, 1, &histSize, &histRange, uniform, accumulate);

    // calculate cumulative distribution from the histogram
    std::vector<float> accumulator(histSize);
    accumulator[0] = hist.at<float>(0);
    for (int i = 1; i < histSize; i++)
    {
        accumulator[i] = accumulator[i - 1] + hist.at<float>(i);
    }

    // locate points that cuts at required value
    float max = accumulator.back();
    clipHistPercent *= (max / 100.0); //make percent as absolute
    clipHistPercent /= 2.0; // left and right wings
    // locate left cut
    minGray = 0;
    while (accumulator[minGray] < clipHistPercent)
        minGray++;

    // locate right cut
    maxGray = histSize - 1;
    while (accumulator[maxGray] >= (max - clipHistPercent))
        maxGray--;
}

// current range
float inputRange = maxGray - minGray;

alpha = (histSize - 1) / inputRange;   // alpha expands current range to histsize range
beta = -minGray * alpha;             // beta shifts current range so that minGray will go to 0

// Apply brightness and contrast normalization
// convertTo operates with saurate_cast
src.convertTo(dst, -1, alpha, beta);

// restore alpha channel from source
if (dst.type() == CV_8UC4)
{
    int from_to[] = { 3, 3};
    mixChannels(&src, 4, &dst,1, from_to, 1);
}
return;

}
}

我创建了一个类extends org.opencv.core.Mat

public class SMat extends Mat {
public void autofix(Mat m,float clip){
    MainActivity.native_autofix(nativeObj,m.nativeObj,clip);
}
}

并在主活动中使用它

Bitmap bm1 = BitmapFactory.decodeResource(getResources(),R.mipmap.s3);
SMat mat1 = new SMat();
SMat mat2 = new SMat();
Utils.bitmapToMat(bm1,mat1);
mat1.autofix(mat2,5);
Bitmap bm2 = Bitmap.createBitmap(bm1);
Utils.matToBitmap(mat1,bm2);
iv2.setImageBitmap(bm2);

调试时，我发现混音频道功能是原因，如果评论一下，一切都会好的。我不知道为什么会错。请帮忙！谢谢大家！

Answer 1

我找到了解决方案，只需将第二个参数更改为1，因为源Mat仅包含一个Mat :D。

Answer 2

源矩阵和目标矩阵必须具有相同的大小和深度。

您可以从源矩阵克隆目标矩阵的大小，如下所示

Mat dst=src.clone（）；

在目标字段中，它具有相同的原始图像的大小和深度，然后将其传递给混合通道函数