:) I'm programming an algorithm for detect symmetric radial center of an image, to detect eyes position into face framePicture. I know that already exist a project of public domain that do this work, but i would base my work about another kind of studies.
This is the scenario:
Doing by hand this manipulation frame by frame, i have seen that writting code on java layer, like this:
private Mat mGray = new Mat(height,width,CvType.CV_8U);
private Mat mOut = new Mat(height,width,CvType.CV_8U);
private Mat mIntermediateMat = Mat.zeros(height,width,CvType.CV_32F);
[...common methods of opencv app...]
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
switch (ImageManipulationsActivity.viewMode) {
case ImageManipulationsActivity.VIEW_MODE_RGBA:
mOut = inputFrame.rgba();
break;
case ImageManipulationsActivity.VIEW_MODE_MODIFY:
mGray = inputFrame.gray();
int h = mGray.rows();
int w = mGray.cols();
int sobxVal,sobyVal;
/**
* Appling manually sobel filtering to calculate dx and dy image,
* moreover calculate magnitudo matrix and cosValue and sinValue
* matrices for computing, using lut techniques.
*/
for(int i = 1; i < h-1; i++)
for(int j = 1; j < w-1; j++) {
sobxVal = (int) (
((int)mGray.get(i-1,j)[0] << 1) +
mGray.get(i-1,j-1)[0] +
mGray.get(i-1,j+1)[0] - (
((int)mGray.get(i+1,j)[0] << 1) +
mGray.get(i+1,j-1)[0] +
mGray.get(i+1,j+1)[0] ) );
sobyVal = (int) (
((int)mGray.get(i,j-1)[0] << 1) +
mGray.get(i-1,j-1)[0] +
mGray.get(i+1,j-1)[0] - (
((int)mGray.get(i,j+1)[0] << 1) +
mGray.get(i-1,j+1)[0] +
mGray.get(i+1,j+1)[0] ) );
// compute magnitudo and atan2
}
// ...other calculations...
Core.convertScaleAbs(mIntermediateMat, mOut);
}
return mOut;
}
is not all efficient! So I decided to write c++ for a native function to manipulate matrix in this way:
Code by c++ side
#include <jni.h>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/features2d/features2d.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <math.h>
#include <vector>
#include <android/log.h>
#define LOG_TAG "Example Filter"
#define LOGD(...) ((void)__android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__))
#define RADIUS 10
#define _K 9.9
#define _A 2 //radial strictness parameter, found experimentally
using namespace std;
using namespace cv;
extern "C" {
JNIEXPORT void JNICALL Java_org_opencv_samples_tutorial2_Tutorial2Activity_FindFeatures(
JNIEnv* env,
jobject,
jlong addrGray,
jlong addrRgba,
jlong addrlutCosSin,
jlong addrlutM );
JNIEXPORT void JNICALL Java_org_opencv_samples_tutorial2_Tutorial2Activity_FindFeatures(
JNIEnv* env,
jobject,
jlong addrGray,
jlong addrOut,
jlong addrlutCosSin,
jlong addrlutM )
{
Mat& mGr = *(Mat*)addrGray;
Mat& mOut = *(Mat*)addrOut;
Mat& lutCosSin = *(Mat*)addrlutCosSin;
Mat& lutM = *(Mat*)addrlutM;
int w = mGr.cols;
int h = mGr.rows;
double sobelxVal,sobelyVal,angle;
Mat magnitudo(h,w,CV_32F,Scalar(0));
Mat xMat(h,w,CV_8S,Scalar(0));
Mat yMat(h,w,CV_8S,Scalar(0));
Mat oMat(h,w,CV_32F,Scalar(0));
Mat mMat(h,w,CV_32F,Scalar(0));
/*
* Convolves Matrix with Sobel ky kernel and Sobel kx kernel
*ky = [ 1 2 1 ;
* 0 0 0 ;
* -1 -2 -1 ]
*
*kx = [ 1 0 -1 ;
* 2 0 -2 ;
* 1 0 -1 ]
*
* doing dedicated computation
*/
for( int i = 1; i < h-1; i++ )
{
for (int j = 1; j < w-1; j++ )
{
sobelxVal = (mGr.at<int>(i-1,j) << 1) +
mGr.at<int>(i-1,j-1) +
mGr.at<int>(i-1,j+1) - (
(mGr.at<int>(i+1,j) << 1) +
mGr.at<int>(i+1,j-1) +
mGr.at<int>(i+1,j+1) );
sobelyVal = (mGr.at<int>(i,j-1) << 1) +
mGr.at<int>(i-1,j-1) +
mGr.at<int>(i+1,j-1) - (
(mGr.at<int>(i,j+1) << 1) +
mGr.at<int>(i-1,j+1) +
mGr.at<int>(i+1,j+1) );
magnitudo.at<double>(i,j) = lutM.at<double>((int)sobelxVal+255/4,(int)sobelxVal+255/4);
angle = floor(atan2(sobelyVal,sobelxVal)*180/M_PI);
xMat.at<double>(i,j) = lutCosSin.at<double>(0,angle);
yMat.at<double>(i,j) = lutCosSin.at<double>(1,angle);
}
}
// other code calculation to determine mOut matrix values
}
}
By java code side
private Mat mRgba;
private Mat mGray;
/*
* Matrix of 360 cols and 2 rows
* row[0] cos values
* row[1] sin values
*/
private static Mat lutCosSin;
/*
* Matrix 510 x 510
* where lutM(i,j) = atan2(i,j)
*/
private static Mat lutMagnitudo
// common methods and declarations...
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
final int viewMode = mViewMode;
switch (viewMode) {
case VIEW_MODE_RGBA:
// input frame has RBGA format
mRgba = inputFrame.rgba();
break;
case VIEW_MODE_FEATURES:
// input frame has RGBA format
mGray = inputFrame.gray();
mRgba = Mat.zeros(mGray.rows(), mGray.cols(), mGray.type());
FindFeatures(
mGray.getNativeObjAddr(),
mRgba.getNativeObjAddr(),
lutCosSin.getNativeObjAddr(),
lutMagnitudo.getNativeObjAddr()
);
//Core.convertScaleAbs(mRgba, mRgba);
// Log.d(TAG, "Called native function :"+mRgba.submat(new Range(0,5), new Range(0,5)).toString()+
// "\nAngles matrix:"+mGray);
break;
}
return mRgba;
}
public native void FindFeatures(long matAddrGr, long matAddrRgba, long matAddrlutCS, long matAddrlutM);
the first important issue of this snipped code is that on accessing to mGr cells with "at" method in this way:
mGr.at<int>(i,j)
previus check that mGr type is int, the returned values isn't the effective gray level pixel of gray frame (i saw it by log).
I suppose that there are linkin bug of matrix from java code to c++ code, but i'm not sure for this.
I hope may anyone help me to solve this issue XD !!
