Hello Community. I've got that litte snipped here. As you can see, Im accessing the pixel value kind of block-wise and use the columns pixel values as bits for a unsigned int. Block number and unsigned int serve as coordinates for another pixel in another image, set to 255.
cv::Mat1b devideAndConquer(const cv::Mat1b &raw, cv::Size2i &blockCount, cv::Size2i &blockSize){
int wordBlockSize = std::pow(2,blockSize.height);
cv::Mat1b word = cv::Mat1b::zeros(blockCount.width,wordBlockSize);
for(uint8_t b = 0; b < blockCount.width; ++b) {
for (uint8_t w = 0; w < blockSize.width; ++w) {
unsigned int n = 0;
for (uint8_t h = 0; h < (blockSize.height); ++h) {
std::cout << (int)(raw.at<uchar>(b*blockSize.width+w,h));
n = (n << 1) + (raw.at<uchar>(b*blockSize.width+w,h) > 0 ? 1 : 0);
}
std::cout <<":"<< n << "\t";
word.at<uchar>(b,n) = 0xFF;
}
}
std::cout << std::endl;
return word;
}
I've tested everything. After hours of debugging I've found the following: Sometimes the return value of raw.at<uchar>(b*blockSize.width+w,h) is inconsistent between calls of devideAndConquer.
I used this Code to test my assumptions:
cv::Size2i blockCount(13,1);
blockSize.height = 10;
blockSize.width = 16;
cv::Mat1b dummy(blockCount.height*blockSize.height,blockCount.width*blockSize.width);
do{
cv::randu(dummy, 0, 2);
} while(cv::countNonZero(dummy) == 0);
do{
cv::Mat1b a = devideAndConquer(dummy,blockCount,blockSize);
cv::Mat1b b = devideAndConquer(dummy,blockCount,blockSize);
cv::Mat1b c;
cv::compare(a,b,c,CV_COMP_BHATTACHARYYA);
cv::imshow("Window",c);
cv::waitKey();
}while(cv::countNonZero(c) != 0);
In theses inconsistend cases, the output of the first call for one block is 0000000000:0, on the second call its 255000000000:512. So the return value of on .at call that should be 0 is 255.
dummy isn't touched. When I CV_COMP_BHATTACHARYYA on the Dummy before the calls and after the Calls, the result is 0 nonZero Pixels.
On 3th and 4th call, even more values are flipped but they are consistently flipped.
Do I miss something? Have I made an error? Or is there some bogus magic happening thats flipping pixels? Latest OpenCV 2.4 is used on an MacBookPro (13", Mid2011) with 4GB RAM and i7.