Forums - Problem with Image Rectification

Hello to all,

I need some help to use some functions of image transformation. My objective is to rectify the paper in this photo (http://dl.dropbox.com/u/28086295/test3.jpg), but i can't do it. The code is the following:

RectifyImage.h

#ifndef IMAGEPROCESSING_H
#define IMAGEPROCESSING_H

#include <jni.h>

extern "C" {

JNIEXPORT void JNICALL Java_com_example_rectifyimage_ImageProcessing_applyRectificationNative
(
    JNIEnv* env,
    jobject obj,
    jintArray src,
    jbooleanArray dst,
    jint width,
    jint height
);

void convertRGBtoYUV(jboolean * yuv420p, jint * argb, jint width, jint height);
}
#endif

RectifyImage.cpp

#include "RectifyImage.h"

#include <stdlib.h>
#include <fastcv.h>
#include <android/log.h>
#include <math.h>

#define LOG_TAG    "RectifyImage.cpp"

#define DPRINTF(...)  __android_log_print(ANDROID_LOG_DEBUG,LOG_TAG,__VA_ARGS__)
#define IPRINTF(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define EPRINTF(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)

JNIEXPORT void JNICALL Java_com_example_rectifyimage_ImageProcessing_applyRectificationNative
(
    JNIEnv* env,
    jobject obj,
    jintArray src,
    jbooleanArray dst,
    jint width,
    jint height
)
{
    jboolean yuvData[width * height * 3 / 2];
    jint* srcData = NULL;
    jboolean* dstData = NULL;
    jboolean isCopy = 0;
   
    jint stride = width;
    jint frameSize = width*height;
    jfloat projMatrix[];
    jfloat srcPoint[]={77.0f, 241.0f, 327.0f, 43.0f, 490.0f, 183.0f, 227.0f, 425.0f};
    jfloat dstPoint[]={0.0f, 0.0f, 297.0f, 0.0f, 297.0f, 210.0f, 0.0f, 210.0f};
   
    srcData = env->GetIntArrayElements(src, &isCopy);
    dstData = env->GetBooleanArrayElements(dst, &isCopy);

    convertRGBtoYUV(yuvData, srcData, width, height);
   
    fcvGetPerspectiveTransformf32(srcPoint, dstPoint, projMatrix);
    fcvWarpPerspectiveu8_v2(yuvData, width, height, width, dstData, width, height, width, projMatrix);
   
    // copy U,V data that are not used by the filters
    memcpy(dstData+frameSize, yuvData+frameSize, frameSize/2);
   
    env->ReleaseIntArrayElements(src, srcData, JNI_ABORT);
    env->ReleaseBooleanArrayElements(dst, dstData, JNI_ABORT);
}

void convertRGBtoYUV(jboolean * yuv420p, jint * argb, jint width, jint height)
{
    int frameSize = width * height;

    int yIndex = 0;
    int uvIndex = frameSize;

    int R, G, B, Y, U, V;
    int index = 0;
    for (int j = 0; j < height; j++) {
        for (int i = 0; i < width; i++) {
            // a = (argb[index] & 0xff000000) >> 24;
            R = (argb[index] & 0xff0000) >> 16;
            G = (argb[index] & 0xff00) >> 8;
            B = (argb[index] & 0xff) >> 0;

            Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
            U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
            V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;

            yuv420p[yIndex++] = (jboolean) ((Y < 0) ? 0 : ((Y > 255) ? 255 : Y));
            if (j % 2 == 0 && index % 2 == 0) {
                yuv420p[uvIndex++] = (jboolean) ((V < 0) ? 0 : ((V > 255) ? 255 : V));
                yuv420p[uvIndex++] = (jboolean) ((U < 0) ? 0 : ((U > 255) ? 255 : U));
            }

            index++;
        }
    }
}

I'm sure that transformation from RGB to YUV is working, because i've used it in another piece of code. The part that does not work is the rectification. I obtain an image totally different from image that i would like to. Moreover the projection matrix calculated with matlab is totally different from the projection matrix obtained with fcvGetPerspectiveTransformf32. It's normal?
I've also tried to use the matlab projection matrix with the function fcvWarpPerspectiveu8_v2 but i obtain a black image.

Someone can help me?
Thanks a lot in advance!