Nagram/TMessagesProj/jni/secureid_ocr.cpp
2018-07-30 09:07:02 +07:00

640 lines
21 KiB
C++

#include <jni.h>
#include <android/bitmap.h>
#include <android/asset_manager.h>
#include <android/asset_manager_jni.h>
#include <android/log.h>
#include <vector>
#include <utility>
#include <string>
#include <math.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <libyuv.h>
#include "fast-edge.h"
#include "genann.h"
#ifndef max
#define max(a, b) (a>b ? a : b)
#define min(a, b) (a<b ? a : b)
#endif
#define TAG "ocr"
#define _LOG_WRAP(...) __VA_ARGS__
#define LOGV(...) {__android_log_print(ANDROID_LOG_VERBOSE, TAG, _LOG_WRAP(__VA_ARGS__));}
#define LOGD(...) {__android_log_print(ANDROID_LOG_DEBUG, TAG, _LOG_WRAP(__VA_ARGS__));}
#define LOGI(...) {__android_log_print(ANDROID_LOG_INFO, TAG, _LOG_WRAP(__VA_ARGS__));}
#define LOGW(...) {__android_log_print(ANDROID_LOG_WARN, TAG, _LOG_WRAP(__VA_ARGS__));}
#define LOGE(...) {__android_log_print(ANDROID_LOG_ERROR, TAG, _LOG_WRAP(__VA_ARGS__));}
namespace ocr{
struct line{
double theta;
double r;
};
std::vector<line> detectLines(struct image* img, int threshold){
// The size of the neighbourhood in which to search for other local maxima
const int neighbourhoodSize = 4;
// How many discrete values of theta shall we check?
const int maxTheta = 180;
// Using maxTheta, work out the step
const double thetaStep = M_PI / maxTheta;
int width=img->width;
int height=img->height;
// Calculate the maximum height the hough array needs to have
int houghHeight = (int) (sqrt(2.0) * max(height, width)) / 2;
// Double the height of the hough array to cope with negative r values
int doubleHeight = 2 * houghHeight;
// Create the hough array
int* houghArray = new int[maxTheta*doubleHeight];
memset(houghArray, 0, sizeof(int)*maxTheta*doubleHeight);
// Find edge points and vote in array
int centerX = width / 2;
int centerY = height / 2;
// Count how many points there are
int numPoints = 0;
// cache the values of sin and cos for faster processing
double* sinCache = new double[maxTheta];
double* cosCache = new double[maxTheta];
for (int t = 0; t < maxTheta; t++) {
double realTheta = t * thetaStep;
sinCache[t] = sin(realTheta);
cosCache[t] = cos(realTheta);
}
// Now find edge points and update the hough array
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
// Find non-black pixels
if ((img->pixel_data[y*width+x] & 0x000000ff) != 0) {
// Go through each value of theta
for (int t = 0; t < maxTheta; t++) {
//Work out the r values for each theta step
int r = (int) (((x - centerX) * cosCache[t]) + ((y - centerY) * sinCache[t]));
// this copes with negative values of r
r += houghHeight;
if (r < 0 || r >= doubleHeight) continue;
// Increment the hough array
houghArray[t*doubleHeight+r]++;
}
numPoints++;
}
}
}
// Initialise the vector of lines that we'll return
std::vector<line> lines;
// Only proceed if the hough array is not empty
if (numPoints == 0){
delete[] houghArray;
delete[] sinCache;
delete[] cosCache;
return lines;
}
// Search for local peaks above threshold to draw
for (int t = 0; t < maxTheta; t++) {
//loop:
for (int r = neighbourhoodSize; r < doubleHeight - neighbourhoodSize; r++) {
// Only consider points above threshold
if (houghArray[t*doubleHeight+r] > threshold) {
int peak = houghArray[t*doubleHeight+r];
// Check that this peak is indeed the local maxima
for (int dx = -neighbourhoodSize; dx <= neighbourhoodSize; dx++) {
for (int dy = -neighbourhoodSize; dy <= neighbourhoodSize; dy++) {
int dt = t + dx;
int dr = r + dy;
if (dt < 0) dt = dt + maxTheta;
else if (dt >= maxTheta) dt = dt - maxTheta;
if (houghArray[dt*doubleHeight+dr] > peak) {
// found a bigger point nearby, skip
goto loop;
}
}
}
// calculate the true value of theta
double theta = t * thetaStep;
// add the line to the vector
line l={theta, (double)r-houghHeight};
lines.push_back(l);
}
loop:
continue;
}
}
delete[] houghArray;
delete[] sinCache;
delete[] cosCache;
return lines;
}
void binarizeBitmapPart(uint32_t* inPixels, unsigned char* outPixels, size_t width, size_t height, size_t inStride, size_t outStride){
uint32_t histogram[256]={0};
uint32_t intensitySum=0;
for(unsigned int y=0;y<height;y++){
for(unsigned int x=0;x<width;x++){
uint32_t px=inPixels[y*inStride/sizeof(uint32_t)+x];
int l=(((px & 0xFF)+((px & 0xFF00) >> 8)+((px & 0xFF0000) >> 16))/3);
outPixels[y*outStride+x]=(unsigned char)l;
histogram[l]++;
intensitySum+=l;
}
}
int threshold=0;
double best_sigma = 0.0;
int first_class_pixel_count = 0;
int first_class_intensity_sum = 0;
for (int thresh = 0; thresh < 255; ++thresh) {
first_class_pixel_count += histogram[thresh];
first_class_intensity_sum += thresh * histogram[thresh];
double first_class_prob = first_class_pixel_count / (double) (width*height);
double second_class_prob = 1.0 - first_class_prob;
double first_class_mean = first_class_intensity_sum / (double) first_class_pixel_count;
double second_class_mean = (intensitySum - first_class_intensity_sum)
/ (double) ((width*height) - first_class_pixel_count);
double mean_delta = first_class_mean - second_class_mean;
double sigma = first_class_prob * second_class_prob * mean_delta * mean_delta;
if (sigma > best_sigma) {
best_sigma = sigma;
threshold = thresh;
}
}
for(unsigned int y=0;y<height;y++){
for(unsigned int x=0;x<width;x++){
uint32_t px=inPixels[y*inStride/sizeof(uint32_t)+x];
outPixels[y*outStride+x]=(px & 0xFF)<threshold && ((px & 0xFF00) >> 8)<threshold && ((px & 0xFF0000) >> 16)<threshold ? (unsigned char)255 : (unsigned char)0;
}
}
}
}
extern "C" JNIEXPORT jintArray Java_org_telegram_messenger_MrzRecognizer_findCornerPoints(JNIEnv* env, jclass clasz, jobject bitmap){
AndroidBitmapInfo info={0};
if(AndroidBitmap_getInfo(env, bitmap, &info)!=ANDROID_BITMAP_RESULT_SUCCESS){
return NULL;
}
if(info.format!=ANDROID_BITMAP_FORMAT_RGBA_8888){
return NULL;
}
//LOGD("Bitmap info: %d x %d, stride %d", info.width, info.height, info.stride);
unsigned int width=info.width;
unsigned int height=info.height;
uint32_t* bitmapPixels;
if(AndroidBitmap_lockPixels(env, bitmap, reinterpret_cast<void**>(&bitmapPixels))!=ANDROID_BITMAP_RESULT_SUCCESS){
LOGE("AndroidBitmap_lockPixels failed!");
return NULL;
}
struct ocr::image imgIn, imgOut;
imgIn.width=imgOut.width=width;
imgIn.height=imgOut.height=height;
imgIn.pixel_data=(unsigned char*)malloc(width*height);
imgOut.pixel_data=(unsigned char*)calloc(width*height, 1);
for(unsigned int y=0;y<height;y++){
for(unsigned int x=0;x<width;x++){
uint32_t px=bitmapPixels[info.stride*y/sizeof(uint32_t)+x];
imgIn.pixel_data[width*y+x]=(unsigned char) (((px & 0xFF)+((px & 0xFF00) >> 8)+((px & 0xFF0000) >> 16))/3);
}
}
AndroidBitmap_unlockPixels(env, bitmap);
ocr::canny_edge_detect(&imgIn, &imgOut);
std::vector<ocr::line> lines=ocr::detectLines(&imgOut, 100);
for(int i=0;i<width*height;i++){
imgOut.pixel_data[i]/=2;
}
std::vector<std::vector<ocr::line>> parallelGroups;
for(int i=0;i<36;i++){
parallelGroups.emplace_back();
}
ocr::line* left=NULL;
ocr::line* right=NULL;
ocr::line* top=NULL;
ocr::line* bottom=NULL;
for(std::vector<ocr::line>::iterator l=lines.begin();l!=lines.end();){
// remove lines at irrelevant angles
if(!(l->theta>M_PI*0.4 && l->theta<M_PI*0.6) && !(l->theta<M_PI*0.1 || l->theta>M_PI*0.9)){
l=lines.erase(l);
continue;
}
// remove vertical lines close to the middle of the image
if((l->theta<M_PI*0.1 || l->theta>M_PI*0.9) && abs((int)l->r)<height/4){
l=lines.erase(l);
continue;
}
// find the leftmost and rightmost lines
if(l->theta<M_PI*0.1 || l->theta>M_PI*0.9){
double rk=l->theta<0.5 ? 1.0 : -1.0;
if(!left || left->r>l->r*rk){
left=&*l;
}
if(!right || right->r<l->r*rk){
right=&*l;
}
}
// group parallel-ish lines with 5-degree increments
parallelGroups[floor(l->theta/M_PI*36)].push_back(*l);
++l;
}
// the text on the page tends to produce a lot of parallel lines - so we assume the top & bottom edges of the page
// are topmost & bottommost lines in the largest group of horizontal lines
std::vector<ocr::line>& largestParallelGroup=parallelGroups[0];
for(std::vector<std::vector<ocr::line>>::iterator group=parallelGroups.begin();group!=parallelGroups.end();++group){
if(largestParallelGroup.size()<group->size())
largestParallelGroup=*group;
}
for(std::vector<ocr::line>::iterator l=largestParallelGroup.begin();l!=largestParallelGroup.end();++l){
// If the image is horizontal, we assume it's just the data page or an ID card so we're going for the topmost line.
// If it's vertical, it likely contains both the data page and the page adjacent to it so we're going for the line that is closest to the center of the image.
// Nobody in their right mind is going to be taking vertical pictures of ID cards, right?
if(width>height){
if(!top || top->r>l->r){
top=&*l;
}
}else{
if(!top || fabs(l->r)<fabs(top->r)){
top=&*l;
}
}
if(!bottom || bottom->r<l->r){
bottom=&*l;
}
}
jintArray result=NULL;
if(top && bottom && left && right){
//LOGI("bottom theta %f", bottom->theta);
if(bottom->theta>1.65 || bottom->theta<1.55){
//LOGD("left: %f, right: %f\n", left->r, right->r);
int points[8]={0};
bool foundTopLeft=false, foundTopRight=false, foundBottomLeft=false, foundBottomRight=false;
double centerX=width/2.0;
double centerY=height/2.0;
double ltsin=sin(left->theta);
double ltcos=cos(left->theta);
double rtsin=sin(right->theta);
double rtcos=cos(right->theta);
double ttsin=sin(top->theta);
double ttcos=cos(top->theta);
double btsin=sin(bottom->theta);
double btcos=cos(bottom->theta);
for (int y = -((int)height)/4; y < (int)height; y++) {
int lx = (int) (((left->r - ((y - centerY) * ltsin)) / ltcos) + centerX);
int ty = (int) (((top->r - ((lx - centerX) * ttcos)) / ttsin) + centerY);
if(ty==y){
points[0]=lx;
points[1]=y;
foundTopLeft=true;
if(foundTopRight)
break;
}
int rx = (int) (((right->r - ((y - centerY) * rtsin)) / rtcos) + centerX);
ty = (int) (((top->r - ((rx - centerX) * ttcos)) / ttsin) + centerY);
if(ty==y){
points[2]=rx;
points[3]=y;
foundTopRight=true;
if(foundTopLeft)
break;
}
}
for (int y = height+height/3; y>=0; y--) {
int lx = (int) (((left->r - ((y - centerY) * ltsin)) / ltcos) + centerX);
int by = (int) (((bottom->r - ((lx - centerX) * btcos)) / btsin) + centerY);
if(by==y){
points[4]=lx;
points[5]=y;
foundBottomLeft=true;
if(foundBottomRight)
break;
}
int rx = (int) (((right->r - ((y - centerY) * rtsin)) / rtcos) + centerX);
by = (int) (((bottom->r - ((rx - centerX) * btcos)) / btsin) + centerY);
if(by==y){
points[6]=rx;
points[7]=y;
foundBottomRight=true;
if(foundBottomLeft)
break;
}
}
if(foundTopLeft && foundTopRight && foundBottomLeft && foundBottomRight){
result=env->NewIntArray(8);
env->SetIntArrayRegion(result, 0, 8, points);
//LOGD("Points: (%d %d) (%d %d) (%d %d) (%d %d)", points[0], points[1], points[2], points[3], points[4], points[5], points[6], points[7]);
}
}else{
//LOGD("No perspective correction needed");
}
}
free(imgIn.pixel_data);
free(imgOut.pixel_data);
return result;
}
extern "C" JNIEXPORT jobjectArray Java_org_telegram_messenger_MrzRecognizer_binarizeAndFindCharacters(JNIEnv* env, jclass clasz, jobject inBmp, jobject outBmp){
AndroidBitmapInfo inInfo={0}, outInfo={0};
if(AndroidBitmap_getInfo(env, inBmp, &inInfo)!=ANDROID_BITMAP_RESULT_SUCCESS || AndroidBitmap_getInfo(env, outBmp, &outInfo)!=ANDROID_BITMAP_RESULT_SUCCESS){
LOGE("AndroidBitmap_getInfo failed");
return NULL;
}
if(inInfo.width!=outInfo.width || inInfo.height!=outInfo.height || inInfo.format!=ANDROID_BITMAP_FORMAT_RGBA_8888 || outInfo.format!=ANDROID_BITMAP_FORMAT_A_8){
LOGE("bitmap validation failed");
return NULL;
}
unsigned int height=inInfo.height;
unsigned int width=inInfo.width;
uint32_t* inPixels;
unsigned char* outPixels;
if(AndroidBitmap_lockPixels(env, inBmp, reinterpret_cast<void**>(&inPixels))!=ANDROID_BITMAP_RESULT_SUCCESS){
LOGE("AndroidBitmap_lockPixels failed");
return NULL;
}
if(AndroidBitmap_lockPixels(env, outBmp, reinterpret_cast<void**>(&outPixels))!=ANDROID_BITMAP_RESULT_SUCCESS){
AndroidBitmap_unlockPixels(env, inBmp);
LOGE("AndroidBitmap_lockPixels failed");
return NULL;
}
for(unsigned int y=0;y<height;y+=120){
for(unsigned int x=0; x<width; x+=120){
int partWidth=x+120<width ? 120 : (width-x);
int partHeight=y+120<height ? 120 : (height-y);
ocr::binarizeBitmapPart(&inPixels[(y*inInfo.stride/sizeof(uint32_t))+x], outPixels+(y*outInfo.stride)+x, partWidth, partHeight, inInfo.stride, outInfo.stride);
}
}
// remove any single pixels without adjacent ones - these are usually noise
for(unsigned int y=height/2;y<height-1;y++){
unsigned int yOffset=y*outInfo.stride;
unsigned int yOffsetPrev=(y-1)*outInfo.stride;
unsigned int yOffsetNext=(y+1)*outInfo.stride;
for(unsigned int x=1;x<width-1;x++){
int pixelCount=0;
if(outPixels[yOffsetPrev+x-1]!=0)
pixelCount++;
if(outPixels[yOffsetPrev+x]!=0)
pixelCount++;
if(outPixels[yOffsetPrev+x+1]!=0)
pixelCount++;
if(outPixels[yOffset+x-1]!=0)
pixelCount++;
if(outPixels[yOffset+x]!=0)
pixelCount++;
if(outPixels[yOffset+x+1]!=0)
pixelCount++;
if(outPixels[yOffsetNext+x-1]!=0)
pixelCount++;
if(outPixels[yOffsetNext+x]!=0)
pixelCount++;
if(outPixels[yOffsetNext+x+1]!=0)
pixelCount++;
if(pixelCount<3)
outPixels[yOffset+x]=0;
}
}
// search from the bottom up for continuous areas of mostly empty pixels
unsigned int consecutiveEmptyRows=0;
std::vector<std::pair<unsigned int, unsigned int>> emptyAreaYs;
for(unsigned int y=height-1;y>=height/2;y--){
unsigned int consecutiveEmptyPixels=0;
unsigned int maxEmptyPixels=0;
for(unsigned int x=0;x<width;x++){
if(outPixels[y*outInfo.stride+x]==0){
consecutiveEmptyPixels++;
}else{
maxEmptyPixels=max(maxEmptyPixels, consecutiveEmptyPixels);
consecutiveEmptyPixels=0;
}
}
maxEmptyPixels=max(maxEmptyPixels, consecutiveEmptyPixels);
if(maxEmptyPixels>width/10*8){
consecutiveEmptyRows++;
}else if(consecutiveEmptyRows>0){
emptyAreaYs.emplace_back(y, y+consecutiveEmptyRows);
consecutiveEmptyRows=0;
}
}
std::vector<jobjectArray> result;
jclass rectClass=env->FindClass("android/graphics/Rect");
jmethodID rectConstructor=env->GetMethodID(rectClass, "<init>", "(IIII)V");
// using the areas found above, do the same thing but horizontally and between them in an attempt to ultimately find the bounds of the MRZ characters
for(std::vector<std::pair<unsigned int, unsigned int>>::iterator p=emptyAreaYs.begin();p!=emptyAreaYs.end();++p){
std::vector<std::pair<unsigned int, unsigned int>>::iterator next=std::next(p);
if(next!=emptyAreaYs.end()){
unsigned int lineHeight=p->first-next->second;
// An MRZ line can't really be this thin so this probably isn't one
if(lineHeight<10)
continue;
unsigned int consecutiveEmptyCols=0;
std::vector<std::pair<unsigned int, unsigned int>> emptyAreaXs;
for(unsigned int x=0;x<width;x++){
unsigned int consecutiveEmptyPixels=0;
unsigned int maxEmptyPixels=0;
unsigned int bottomFilledPixels=0; // count these separately because we want those L's recognized correctly
for(unsigned int y=next->second;y<p->first;y++){
if(outPixels[y*outInfo.stride+x]==0){
consecutiveEmptyPixels++;
}else{
maxEmptyPixels=max(maxEmptyPixels, consecutiveEmptyPixels);
consecutiveEmptyPixels=0;
if(y>p->first-3)
bottomFilledPixels++;
}
}
maxEmptyPixels=consecutiveEmptyPixels;
if(lineHeight-maxEmptyPixels<=lineHeight/15 && bottomFilledPixels==0){
consecutiveEmptyCols++;
}else if(consecutiveEmptyCols>0){
emptyAreaXs.emplace_back(x-consecutiveEmptyCols, x);
consecutiveEmptyCols=0;
}
}
if(consecutiveEmptyCols>0){
emptyAreaXs.emplace_back(width-consecutiveEmptyCols, width);
}
if(emptyAreaXs.size()>30){
bool foundLeftPadding=false;
std::vector<jobject> rects;
for(std::vector<std::pair<unsigned int, unsigned int>>::iterator h=emptyAreaXs.begin();h!=emptyAreaXs.end();++h){
std::vector<std::pair<unsigned int, unsigned int>>::iterator nextH=std::next(h);
if(!foundLeftPadding && h->second-h->first>width/35){
foundLeftPadding=true;
}else if(foundLeftPadding && h->second-h->first>width/30){
if(rects.size()>=30){
break;
}else{
// restart the search because now we've (hopefully) found the real padding
rects.erase(rects.begin(), rects.end());
}
}
if(nextH!=emptyAreaXs.end() && foundLeftPadding){
unsigned int top=next->second;
unsigned int bottom=p->first;
// move the top and bottom edges towards each other as part of normalization
for(unsigned int y=top;y<bottom;y++){
bool found=false;
for(unsigned int x=h->second; x<nextH->first; x++){
if(outPixels[y*outInfo.stride+x]!=0){
top=y;
found=true;
break;
}
}
if(found)
break;
}
for(unsigned int y=bottom;y>top;y--){
bool found=false;
for(unsigned int x=h->second; x<nextH->first; x++){
if(outPixels[y*outInfo.stride+x]!=0){
bottom=y;
found=true;
break;
}
}
if(found)
break;
}
if(bottom-top<lineHeight/4)
continue;
if(rects.size()<44){
jobject rect=env->NewObject(rectClass, rectConstructor, h->second, top, nextH->first, bottom);
rects.push_back(rect);
}
}
}
jobjectArray lineArray=env->NewObjectArray(static_cast<jsize>(rects.size()), rectClass, NULL);
int i=0;
for(std::vector<jobject>::iterator r=rects.begin();r!=rects.end();++r){
env->SetObjectArrayElement(lineArray, i, *r);
i++;
}
result.push_back(lineArray);
if((rects.size()>=44 && result.size()==2) || (rects.size()>=30 && result.size()==3)){
break;
}
}
}
}
AndroidBitmap_unlockPixels(env, inBmp);
AndroidBitmap_unlockPixels(env, outBmp);
if(result.empty())
return NULL;
jobjectArray resultArray=env->NewObjectArray(static_cast<jsize>(result.size()), env->GetObjectClass(result[0]), NULL);
int i=0;
for(std::vector<jobjectArray>::iterator a=result.begin();a!=result.end();++a){
env->SetObjectArrayElement(resultArray, static_cast<jsize>(result.size()-i-1), *a);
i++;
}
return resultArray;
}
extern "C" JNIEXPORT jstring Java_org_telegram_messenger_MrzRecognizer_performRecognition(JNIEnv* env, jclass clasz, jobject bitmap, jint numRows, jint numCols, jobject jAssetManager){
AAssetManager* assets=AAssetManager_fromJava(env, jAssetManager);
AAsset* nnData=AAssetManager_open(assets, "secureid_ocr_nn.dat", AASSET_MODE_STREAMING);
if(!nnData){
LOGE("AAssetManager_open failed");
return NULL;
}
struct genann* ann=genann_init(150, 1, 90, 37);
AAsset_read(nnData, ann->weight, sizeof(double)*ann->total_weights);
AAsset_close(nnData);
std::string res;
const char* alphabet="ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890<";
AndroidBitmapInfo info;
unsigned char* pixels;
AndroidBitmap_getInfo(env, bitmap, &info);
if(AndroidBitmap_lockPixels(env, bitmap, reinterpret_cast<void**>(&pixels))!=ANDROID_BITMAP_RESULT_SUCCESS){
LOGE("AndroidBitmap_lockPixels failed");
genann_free(ann);
return NULL;
}
double nnInput[150];
for(int row=0;row<numRows;row++){
for(int col=0;col<numCols;col++){
unsigned int offX=static_cast<unsigned int>(col*10);
unsigned int offY=static_cast<unsigned int>(row*15);
for(unsigned int y=0;y<15;y++){
for(unsigned int x=0;x<10;x++){
nnInput[y*10+x]=(double)pixels[(offY+y)*info.stride+offX+x]/255.0;
}
}
const double* nnOut=genann_run(ann, nnInput);
unsigned int bestIndex=0;
for(unsigned int i=0;i<37;i++){
if(nnOut[i]>nnOut[bestIndex])
bestIndex=i;
}
res+=alphabet[bestIndex];
}
if(row!=numRows-1)
res+="\n";
}
genann_free(ann);
return env->NewStringUTF(res.c_str());
}
extern "C" JNIEXPORT void Java_org_telegram_messenger_MrzRecognizer_setYuvBitmapPixels(JNIEnv* env, jclass clasz, jobject bitmap, jbyteArray jpixels){
jbyte* _pixels=env->GetByteArrayElements(jpixels, NULL);
uint8_t* pixels=reinterpret_cast<uint8_t*>(_pixels);
AndroidBitmapInfo info;
uint32_t* bpixels;
if(AndroidBitmap_getInfo(env, bitmap, &info)==ANDROID_BITMAP_RESULT_SUCCESS){
if(info.format==ANDROID_BITMAP_FORMAT_RGBA_8888){
if(AndroidBitmap_lockPixels(env, bitmap, reinterpret_cast<void**>(&bpixels))==ANDROID_BITMAP_RESULT_SUCCESS){
libyuv::NV12ToARGB(pixels, info.width, pixels+info.width*info.height, info.width, reinterpret_cast<uint8_t*>(bpixels), info.stride, info.width, info.height);
AndroidBitmap_unlockPixels(env, bitmap);
}
}
}
env->ReleaseByteArrayElements(jpixels, _pixels, JNI_ABORT);
}