虽然OpenCV已成功加载到项目中，但在遇到Canny方法之前，已经成功使用了Mat和imgproc.cvtcolor等其他元素（至少我认为是这样）。 * .so文件也存在于jniLibs目录中，但我不明白为什么会出现此错误
以下是日志：
I/OpenCVManager/Helper: C++ Compiler: /usr/local/bin/ccache /opt/android/android-ndk-r10e/toolchains/arm-linux-
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Python 3:
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Interpreter: NOissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wno-narrowing -fdiagnostics-show-option -fomit-frame-pointer -mfpu=neon -fvisibility=hidden -mthumb -fomit-frame-pointer -fno-strict-aliasing -O3 -DNDEBUG -DNDEBUG
08-29 12:1
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Python (for build): /opt/pythonenv/build/bin/python2.7
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Java:
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: ant: /usr/local/bin/ant (ver 1.9.4)
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Java wrappers: YES
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Java tests: YES
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Matlab: NO
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Tests and samples:
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Tests: YES
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Performance tests: NO
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: C/C++ Examples: NO
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: Install path: /Volumes/Linux/builds/master_pack-android/build/o4a/install
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: cvconfig.h is in: /Volumes/Linux/builds/master_pack-android/build/o4a
08-29 12:10:16.818 6248-6248/com.gurankas.bhism.documentscanner I/OpenCVManager/Helper: -----------------------------------------------------------------
08-29 12:10:16.819 6248-6248/com.gurankas.bhism.documentscanner D/OpenCVManager/Helper: Init finished with status 0
08-29 12:10:16.819 6248-6248/com.gurankas.bhism.documentscanner D/OpenCVManager/Helper: Unbind from service
08-29 12:10:16.824 6248-6248/com.gurankas.bhism.documentscanner D/OpenCVManager/Helper: Calling using callback
08-29 12:10:16.824 6248-6248/com.gurankas.bhism.documentscanner I/LensActivity: OpenCV loaded successfully
08-29 12:10:16.882 6248-6408/com.gurankas.bhism.documentscanner I/Adreno-EGL: <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.016_msm8610_LA.BF.1.1.1_RB1__release_AU ()
OpenGL ES Shader Compiler Version: E031.25.03.00
Build Date: 02/11/15 Wed
Local Branch:
Remote Branch: quic/LA.BF.1.1.1_rb1.10
Local Patches: NONE
Reconstruct Branch: AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.016 + 62ca4eb + acd831d + 9f8b442 + e027a02 + cba30ba + 53c303a + a649d79 + 23e16f8 + 5e97da7 + cbd2a44 + 33d072a + 7aacf06 + 72b33e7 + 28f6f60 + b4c13d8 + NOTHING
08-29 12:10:16.884 6248-6408/com.gurankas.bhism.documentscanner I/OpenGLRenderer: Initialized EGL, version 1.4
08-29 12:10:16.904 6248-6408/com.gurankas.bhism.documentscanner D/OpenGLRenderer: Enabling debug mode 0
08-29 12:10:17.049 6248-6248/com.gurankas.bhism.documentscanner W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
08-29 12:10:24.285 6248-6248/com.gurankas.bhism.documentscanner D/LensActivity: File URI = file:///storage/emulated/0/Document%20Scanner/image_10.jpg
08-29 12:10:33.369 6248-6248/com.gurankas.bhism.documentscanner D/LensActivity: 1 1 -1 -1
08-29 12:10:33.369 6248-6248/com.gurankas.bhism.documentscanner D/LensActivity: file:///storage/emulated/0/Document%20Scanner/image_10.jpg
08-29 12:10:33.434 6248-6262/com.gurankas.bhism.documentscanner W/art: Suspending all threads took: 12.494ms
08-29 12:10:35.931 6248-6262/com.gurankas.bhism.documentscanner W/art: Suspending all threads took: 7.088ms
08-29 12:10:47.779 6248-7428/com.gurankas.bhism.documentscanner E/art: No implementation found for void org.opencv.imgproc.Imgproc.Canny_3(long, long, double, double) (tried Java_org_opencv_imgproc_Imgproc_Canny_13 and Java_org_opencv_imgproc_Imgproc_Canny_13__JJDD)
08-29 12:10:47.792 6248-7428/com.gurankas.bhism.documentscanner E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
Process: com.gurankas.bhism.documentscanner, PID: 6248
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:304)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.UnsatisfiedLinkError: No implementation found for void org.opencv.imgproc.Imgproc.Canny_3(long, long, double, double) (tried Java_org_opencv_imgproc_Imgproc_Canny_13 and Java_org_opencv_imgproc_Imgproc_Canny_13__JJDD)
at org.opencv.imgproc.Imgproc.Canny_3(Native Method)
at org.opencv.imgproc.Imgproc.Canny(Imgproc.java:1038)
at com.gurankas.bhism.documentscanner.MyAsyncTask.doInBackground(MyAsyncTask.java:98)
at com.gurankas.bhism.documentscanner.MyAsyncTask.doInBackground(MyAsyncTask.java:27)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
08-29 12:15:47.845 6248-7428/com.gurankas.bhism.documentscanner I/Process: Sending signal. PID: 6248 SIG: 9
我正在执行OpenCV相关操作的asyncTask类：
package com.gurankas.bhism.documentscanner;
import android.content.Context;
import android.graphics.Bitmap;
import android.util.Log;
import android.widget.Toast;
import org.opencv.android.Utils;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.core.TermCriteria;
import org.opencv.imgproc.Imgproc;
import org.opencv.utils.Converters;
import java.util.ArrayList;
import java.util.List;
/**
* Created by bhism on 8/23/2017.
*/
public class MyAsyncTask extends android.os.AsyncTask {
private static final String TAG = "AsyncTask";
Bitmap bitmap1;
Context context;
//constructor initializing the context field
public MyAsyncTask(Context context){
this.context=context;
}
//Main method for the computation of the image
@Override
protected Bitmap doInBackground(Object[] objects)
{
//set-up of the image in the desired format for k-means clustering
Mat samples = new Mat(((LensActivity)context).src.rows() * ((LensActivity)context).src.cols(), 3, CvType.CV_32F);
for( int y = 0; y < ((LensActivity)context).src.rows(); y++ )
{
for( int x = 0; x < ((LensActivity)context).src.cols(); x++ )
{
for( int z = 0; z < 3; z++)
{
samples.put(x + y*((LensActivity)context).src.cols(), z, ((LensActivity)context).src.get(y,x)[z]);
}
}
}
//applying k-means clustering
int clusterCount = 2;
Mat labels = new Mat();
int attempts = 5;
Mat centers = new Mat();
Core.kmeans(samples, clusterCount, labels, new TermCriteria(TermCriteria.MAX_ITER |
TermCriteria.EPS, 10000, 0.0001), attempts,
Core.KMEANS_PP_CENTERS, centers);
//The image with the colour nearest to white will be considered as foreground
double dstCenter0 = calcWhiteDist(centers.get(0, 0)[0], centers.get(0, 1)[0], centers.get(0, 2)[0]);
double dstCenter1 = calcWhiteDist(centers.get(1, 0)[0], centers.get(1, 1)[0], centers.get(1, 2)[0]);
int paperCluster = (dstCenter0 < dstCenter1)?0:1;
//definition of 2 Mat objects needed for next step
Mat srcRes = new Mat( ((LensActivity)context).src.size(), ((LensActivity)context).src.type() );
Mat srcGray = new Mat();
//Performing Segmentation ie displaying all foreground pixels as white and all background pixels as black
for( int y = 0; y < ((LensActivity)context).src.rows(); y++ )
{
for( int x = 0; x < ((LensActivity)context).src.cols(); x++)
{
int cluster_idx = (int)labels.get(x + y*((LensActivity)context).src.cols(),0)[0];
if(cluster_idx != paperCluster)
{
srcRes.put(y,x, 0, 0, 0, 255);
}
else
{
srcRes.put(y,x, 255, 255, 255, 255);
}
}
}
//Apply canny edge detection and then find contours
Imgproc.cvtColor(((LensActivity)context).src, srcGray, Imgproc.COLOR_BGR2GRAY);
Imgproc.Canny(srcGray, srcGray, 50, 150);
List<MatOfPoint> contours = new ArrayList<MatOfPoint>();
Mat hierarchy = new Mat();
Imgproc.findContours(srcGray, contours, hierarchy, Imgproc.RETR_TREE, Imgproc.CHAIN_APPROX_SIMPLE);
//Finding the biggest contour corresponding to the page in the image
int index = 0;
double maxim = Imgproc.contourArea(contours.get(0));
for (int contourIdx = 1; contourIdx < contours.size();contourIdx++)
{
double temp;
temp=Imgproc.contourArea(contours.get(contourIdx));
if(maxim<temp)
{
maxim=temp;
index=contourIdx;
}
}
Mat drawing = Mat.zeros(srcRes.size(), CvType.CV_8UC1);
Imgproc.drawContours(drawing, contours, index, new Scalar(255), 1);
//lines corresponding to the biggest contours used to find the intersection points of these lines to find the corners
Mat lines = new Mat();
Imgproc.HoughLinesP(drawing, lines, 1, Math.PI/180, 70, 30, 10);
ArrayList<Point> corners = new ArrayList<Point>();
for (int i = 0; i < lines.cols(); i++)
{
for (int j = i+1; j < lines.cols(); j++) {
double[] line1 = lines.get(0, i);
double[] line2 = lines.get(0, j);
Point pt = findIntersection(line1, line2);
Log.d("com.packtpub.chapter9", pt.x+" "+pt.y);
if (pt.x >= 0 && pt.y >= 0 && pt.x <= drawing.cols() && pt.y <= drawing.rows())
{
if(!exists(corners, pt)){
corners.add(pt);
Log.d(TAG, "Corner is "+ pt);
}
}
Log.d(TAG, "Point is " + pt);
}
}
sortCorners(corners);
//determination of resultant image size
double top = Math.sqrt(Math.pow(corners.get(0).x - corners.get(1).x, 2) + Math.pow(corners.get(0).y - corners.get(1).y, 2));
double right = Math.sqrt(Math.pow(corners.get(1).x - corners.get(2).x, 2) + Math.pow(corners.get(1).y - corners.get(2).y, 2));
double bottom = Math.sqrt(Math.pow(corners.get(2).x - corners.get(3).x, 2) + Math.pow(corners.get(2).y - corners.get(3).y, 2));
double left = Math.sqrt(Math.pow(corners.get(3).x - corners.get(1).x, 2) + Math.pow(corners.get(3).y - corners.get(1).y, 2));
Mat quad = Mat.zeros(new Size(Math.max(top, bottom), Math.max(left, right)), CvType.CV_8UC3);
//refernce corners
ArrayList<Point> result_pts = new ArrayList<Point>();
result_pts.add(new Point(0, 0));
result_pts.add(new Point(quad.cols(), 0));
result_pts.add(new Point(quad.cols(), quad.rows()));
result_pts.add(new Point(0, quad.rows()));
//perspective transformation
Mat cornerPts = Converters.vector_Point2f_to_Mat(corners);
Mat resultPts = Converters.vector_Point2f_to_Mat(result_pts);
Mat transformation = Imgproc.getPerspectiveTransform(cornerPts,
resultPts);
Imgproc.warpPerspective(((LensActivity)context).srcOrig, quad, transformation,
quad.size());
Imgproc.cvtColor(quad, quad, Imgproc.COLOR_BGR2RGBA);
Bitmap bitmap = Bitmap.createBitmap(quad.cols(), quad.rows(),Bitmap.Config.ARGB_8888);
Utils.matToBitmap(quad, bitmap);
//bitmap1 = Bitmap.createBitmap(bitmap.getHeight(), bitmap.getWidth(), bitmap.getConfig());
bitmap1 = bitmap.copy(Bitmap.Config.ARGB_8888,true);
return bitmap;
}
//identification of 4 corners of the quadrilateral with respect to the center
void sortCorners(ArrayList<Point> corners)
{
ArrayList<Point> top, bottom;
top = new ArrayList<Point>();
bottom = new ArrayList<Point>();
Point center = new Point();
for(int i=0; i<corners.size(); i++){
center.x += corners.get(i).x/corners.size();
center.y += corners.get(i).y/corners.size();
}
for (int i = 0; i < corners.size(); i++)
{
if (corners.get(i).y < center.y)
top.add(corners.get(i));
else
bottom.add(corners.get(i));
}
corners.clear();
if (top.size() == 2 && bottom.size() == 2){
Point top_left = top.get(0).x > top.get(1).x ?
top.get(1) : top.get(0);
Point top_right = top.get(0).x > top.get(1).x ?
top.get(0) : top.get(1);
Point bottom_left = bottom.get(0).x > bottom.get(1).x
? bottom.get(1) : bottom.get(0);
Point bottom_right = bottom.get(0).x > bottom.get(1).x
? bottom.get(0) : bottom.get(1);
top_left.x *= ((LensActivity)context).scaleFactor;
top_left.y *= ((LensActivity)context).scaleFactor;
top_right.x *= ((LensActivity)context).scaleFactor;
top_right.y *= ((LensActivity)context).scaleFactor;
bottom_left.x *= ((LensActivity)context).scaleFactor;
bottom_left.y *= ((LensActivity)context).scaleFactor;
bottom_right.x *= ((LensActivity)context).scaleFactor;
bottom_right.y *= ((LensActivity)context).scaleFactor;
corners.add(top_left);
corners.add(top_right);
corners.add(bottom_right);
corners.add(bottom_left);
}
}
//removal of redundant points in the intersection lines of the biggest contours
static boolean exists(ArrayList<Point> corners, Point pt){
for(int i=0; i<corners.size(); i++){
if(Math.sqrt(Math.pow(corners.get(i).x-pt.x,
2)+Math.pow(corners.get(i).y-pt.y, 2)) < 10){
return true;
}
}
return false;
}
static Point findIntersection(double[] line1, double[] line2) {
double start_x1 = line1[0], start_y1 = line1[1],
end_x1 = line1[2], end_y1 = line1[3], start_x2 =
line2[0], start_y2 = line2[1], end_x2 = line2[2],
end_y2 = line2[3];
double denominator = ((start_x1 - end_x1) * (start_y2 -
end_y2)) - ((start_y1 - end_y1) * (start_x2 - end_x2));
if (denominator!=0)
{
Point pt = new Point();
pt.x = ((start_x1 * end_y1 - start_y1 * end_x1) *
(start_x2 - end_x2) - (start_x1 - end_x1) *
(start_x2 * end_y2 - start_y2 * end_x2)) /
denominator;
pt.y = ((start_x1 * end_y1 - start_y1 * end_x1) *
(start_y2 - end_y2) - (start_y1 - end_y1) *
(start_x2 * end_y2 - start_y2 * end_x2)) /
denominator;
return pt;
}
else
return new Point(-1, -1);
}
static double calcWhiteDist(double r, double g, double b){
return Math.sqrt(Math.pow(255 - r, 2) +
Math.pow(255 - g, 2) + Math.pow(255 - b, 2));
}
@Override
protected void onPostExecute(Object o) {
super.onPostExecute(o);
if(bitmap1!=null) {
((LensActivity)context).ivImage.setImageBitmap(bitmap1);
} else if (((LensActivity)context).errorMsg != null){
// Toast.makeText(this, lensActivity.errorMsg, Toast.LENGTH_SHORT).show();
Log.d(TAG, ((LensActivity)context).errorMsg);
}
}
}
PS由于字数限制，我不得不缩短日志
面对同样的问题，在这里找到了解决方案：https://github.com/opencv/opencv/issues/9497
该问题源于Google Play商店中OpenCV Manager（v3.0.0）的版本早于用于开发的版本（v3.1.1）。
在Android手机上卸载OpenCV Manager并手动安装OpenCV Android sdk zip文件中的APK。