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 2018-10-18 04:49:29 -0500 received badge ● Good Question (source) 2018-01-09 17:58:17 -0500 received badge ● Popular Question (source) 2017-10-10 05:06:04 -0500 received badge ● Notable Question (source) 2017-03-20 03:34:59 -0500 received badge ● Popular Question (source) 2016-07-21 22:29:06 -0500 commented question Normal bayes classifier taking long to train Opencv C++ Thank you so much for these comments! It saved my time to debug what's wrong with my training! train_features.rows = 4544, train_features.cols = 2916 train_labels.rows = 4544, train_labels.cols = 1 test_features.rows = 1156, test_features.cols = 2916 test_labels.rows = 1156, test_labels.cols = 1 Training Bayes: trainset: [2916 x 4544] testset: [2916 x 1156]  2016-06-23 07:06:27 -0500 received badge ● Organizer (source) 2016-06-15 22:35:04 -0500 asked a question How to plot the Precision-Recall Curve (PRC) for a Cascade classifier correctly? I am following OpenCV 3 Blueprints' Chapter 5 Object Detection for Industrial Applications by Steven Puttenams https://www.packtpub.com/application-... The training was successfully completed and I computed the F1 score to be approximately 0.86 as validated on the training dataset of 523 images (just to test if the training was okay). Ex. [root@cobalt workspace]# opencv_traincascade -vec npimages.vec -data output_lbp2/ -numPos 444 -numNeg 888 -bg negatives.txt -numStages 20 -featureType LBP -precalcValBufSize 2048 -precalcIdxBufSize 2048 -w 24 -h 24  However, my main problem is plotting the Precision-Recall Curve (PRC) curve, as suggested in Chapter 5, we could use the ff. to output the score: detector.detectMultiScale(equalize, objects, levels, scores, 1.05, 1, 0, Size(), Size(), true);  But the score I'm getting have very small variations: FILENAME NUM_RECT X Y WIDTH HEIGHT SCORE /home/cobalt/Data/IMG_20160610_170847.jpg 1 190 287 68 68 -1.08848 /home/cobalt/Data/IMG_20160610_170925.jpg 1 186 294 68 68 -1.06534 /home/cobalt/Data/IMG_20160610_170957.jpg 1 189 286 68 68 -1.06534 /home/cobalt/Data/IMG_20160610_171038.jpg 1 191 289 67 67 -0.998512 ... ... .. .. .. ... /home/cobalt/Data/IMG_20160610_205103.jpg 1 190 291 68 68 1.82761 /home/cobalt/Data/IMG_20160610_205106.jpg 1 190 291 68 68 1.82761 /home/cobalt/Data/IMG_20160610_205122.jpg 1 194 297 68 68 1.82761  And this gives rather small values for precision-recall: Ex. coordinates.txt 0.00761905 0.00761905 -1.09 0.00763359 0.00761905 -1.08 0.00763359 0.00761905 -1.07 0.00766284 0.00761905 -1.06 0.00766284 0.00761905 -1.05 0.00766284 0.00761905 -1.04 ... .. ... 0.00952381 0.00761905 1.77 0.00952381 0.00761905 1.78 0.00952381 0.00761905 1.79 0.00952381 0.00761905 1.8 0.00952381 0.00761905 1.81 0.00952381 0.00761905 1.82  With the values above, I cannot get a decent PRC curve. I'm not quite sure what's the problem here.... Though, I can compute the Precision-Recall values using the detect_simple.cpp as I modified it here: https://gist.github.com/melvincabatuan/45a0de3624e99a5c34d308d4a0b99b45  Ex. Output: The number of true positives (TP) are: TP = 628. The number of false positives (FP) are: FP = 185. The number of false negatives (FN) are: FN = 7. Precision = 0.772448. Recall = 0.988976. F1 Score = 0.867403.  2016-05-26 05:03:15 -0500 received badge ● Nice Question (source) 2016-02-01 19:07:36 -0500 received badge ● Nice Question (source) 2015-07-21 03:24:33 -0500 commented question Why are we using 'opencv2' in the include files instead of opencv3? @wuling Thanks for the comment. I had the wrong idea that it has something to do with the OpenCV version. 2015-07-21 03:18:57 -0500 answered a question error: 'COLORMAP_JET' was not declared in this scope Nevermind, I modified COLORMAP_JET including its namespace cv and it worked fine: applyColorMap(src(cv::Range(0, bitmapInfo.height), cv::Range(0, bitmapInfo.width)), output, cv::COLORMAP_JET);  Apparently, this is written in the documentation: cv::ColormapTypes { cv::COLORMAP_AUTUMN = 0, cv::COLORMAP_BONE = 1, cv::COLORMAP_JET = 2, cv::COLORMAP_WINTER = 3, cv::COLORMAP_RAINBOW = 4, cv::COLORMAP_OCEAN = 5, cv::COLORMAP_SUMMER = 6, cv::COLORMAP_SPRING = 7, cv::COLORMAP_COOL = 8, cv::COLORMAP_HSV = 9, cv::COLORMAP_PINK = 10, cv::COLORMAP_HOT = 11, cv::COLORMAP_PARULA = 12  } 2015-07-21 03:14:28 -0500 asked a question error: 'COLORMAP_JET' was not declared in this scope I encountered the following error while trying to display a JET Colormap for my image: applyColorMap(src(cv::Range(0, bitmapInfo.height), cv::Range(0, bitmapInfo.width)), output, COLORMAP_JET);  Error: jni/ImageProcessing.cpp:93:98: error: 'COLORMAP_JET' was not declared in this scope applyColorMap(src(cv::Range(0, bitmapInfo.height), cv::Range(0, bitmapInfo.width)), output, COLORMAP_JET);  2015-07-19 21:44:04 -0500 asked a question Why are we using 'opencv2' in the include files instead of opencv3? This is probably a trivial question but if we are using OpenCV3.0, then why are we using 'opencv2' in the include files instead of opencv3? #include "opencv2/core.hpp" #include "opencv2/core/utility.hpp" #include "opencv2/imgproc.hpp" #include "opencv2/video/background_segm.hpp" #include "opencv2/videoio.hpp" #include "opencv2/highgui.hpp"  2015-07-14 04:57:47 -0500 asked a question Is there a reason why OpenCV does not support (CV_32U) 32 bit depth unsigned integer Mat? For optimization purposes, I'm avoiding the usage of floating numbers, while maintaining a good enough precision. Thus, I want to use 32 bit depth unsigned integer along with Mat data structure. However, from the basic_structures.html documentation, I didn't find CV_32U. Is there a reason why OpenCV does not support it for Mat data structure? A complete list of matrix types contains the following values: CV_8U - 8-bit unsigned integers ( 0..255 ) CV_8S - 8-bit signed integers ( -128..127 ) CV_16U - 16-bit unsigned integers ( 0..65535 ) CV_16S - 16-bit signed integers ( -32768..32767 ) CV_32S - 32-bit signed integers ( -2147483648..2147483647 ) CV_32F - 32-bit floating-point numbers ( -FLT_MAX..FLT_MAX, INF, NAN ) CV_64F - 64-bit floating-point numbers ( -DBL_MAX..DBL_MAX, INF, NAN )  2015-07-13 04:08:40 -0500 commented question Best color difference or distance approximation? 2015-07-12 07:13:47 -0500 commented question Best color difference or distance approximation? @Guanta Thanks for the comment. Can you elaborate why you think cosine distance might be a "good enough approximation" of color difference or distance? It does have the speed potential as reported in EVALUATION OF SIMILARITY MEASUREMENT FOR IMAGE RETRIEVAL... 2015-07-09 20:45:57 -0500 asked a question Best color difference or distance approximation? Currently, a standard way of comparing colors is using "Delta E" metric in CIELab [Color-difference] which is based on Euclidean distance in CIELab color space. However, for certain applications using the distance metric intensively "Delta E" metric could be a bit slow (e.g. RGB2Lab conversion is necessary, floating point operations can be costly, etc.). Is there a "good enough approximation" of color difference or distance? Ex. Weighted Manhattan distance (L1 distance) (in RGB) (as suggested here) Hue Manhattan distance (L1 distance) (in HSV) (as suggested here) Any other suggestions? 2015-07-09 20:25:15 -0500 commented question Running OpenCV SuperpixelSEEDS class without installing contrib module @LBerger Thanks for the comment. I will try it later, but for now, since I'm applying it to Android NDK, I find creating my own SuperpixelSEEDS class and compiling it with JNI easier. 2015-07-08 18:24:43 -0500 commented question Any ideas on detecting and tracking hand touching the body with OpenCV? @StevenPuttemans Thanks for the comment. Mittal et al. context-based proposals to a sliding window shape based detector might be useful in this case. I will try it later. Although, I will drop the skin-based proposals due to the hand-body color similarity. 2015-07-08 17:52:23 -0500 asked a question Running OpenCV SuperpixelSEEDS class without installing contrib module I want to utilize SuperpixelSEEDS class implementing the SEEDS (Superpixels Extracted via Energy-Driven Sampling) superpixels algorithm described in: Michael Van den Bergh, Xavier Boix, Gemma Roig, Luc Van Gool: SEEDS: Superpixels Extracted via Energy-Driven Sampling. International Journal of Computer Vision (IJCV), 2014. Full documentation: However, installing contrib module is not an option in this case since I will be integrating it to Android platform. Is it possible to compile seeds.hpp along with the implementation seeds.cpp with opencv not compiled along with opencv_contrib module? Here's one failed attempt:  \$ g++ -ggdb pkg-config --cflags --libs opencv seeds_sample.cpp seeds.cpp /tmp/ccwT1ohy.o: In function cv::operator*=(cv::Mat&, double const&)': /usr/local/include/opencv2/core/operations.hpp:254: undefined reference to cv::Mat::convertTo(cv::_OutputArray const&, int, double, double) const' /tmp/ccwT1ohy.o: In function cv::operator&=(cv::Mat&, cv::Scalar_ const&)': /usr/local/include/opencv2/core.hpp:1143: undefined reference to cv::noArray()' /tmp/ccwT1ohy.o: In function cv::operator&=(cv::Mat&, cv::Scalar_ const&)': /usr/local/include/opencv2/core/operations.hpp:264: undefined reference to cv::bitwise_and(cv::_InputArray const&, cv::_InputArray const&, cv::_OutputArray const&, cv::_InputArray const&)' /tmp/ccwT1ohy.o: In function main': /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:41: undefined reference to cv::VideoCapture::VideoCapture()' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:48: undefined reference to cv::VideoCapture::open(int)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:53: undefined reference to cv::imread(cv::String const&, int)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:58: undefined reference to cv::VideoCapture::isOpened() const' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:70: undefined reference to cv::namedWindow(cv::String const&, int)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:77: undefined reference to cv::createTrackbar(cv::String const&, cv::String const&, int*, int, void (*)(int, void*), void*)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:78: undefined reference to cv::createTrackbar(cv::String const&, cv::String const&, int*, int, void (*)(int, void*), void*)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:79: undefined reference to cv::createTrackbar(cv::String const&, cv::String const&, int*, int, void (*)(int, void*), void*)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:80: undefined reference to cv::createTrackbar(cv::String const&, cv::String const&, int*, int, void (*)(int, void*), void*)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:91: undefined reference to vtable for cv::VideoCapture' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:93: undefined reference to cv::Mat::copyTo(cv::_OutputArray const&) const' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:107: undefined reference to cv::cvtColor(cv::_InputArray const&, cv::_OutputArray const&, int, int)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:109: undefined reference to cv::getTickCount()' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:114: undefined reference to cv::getTickCount()' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:114: undefined reference to cv::getTickFrequency()' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:124: undefined reference to cv::Mat::setTo(cv::_InputArray const&, cv::_InputArray const&)' /home/cobalt/Workspace/SEEDS/seeds_sample.cpp:130: undefined reference to cv::imshow(cv::String const&, cv::_InputArray const&)' /home/cobalt/Workspace/SEEDS/seeds_sample ... 2015-07-07 04:39:16 -0500 commented question OpenCV SVM (RBF) low test accuracy at 10 % on MNIST As stated in the paper's abstract, the author " rely on the OpenCV implementations of k-Nearest Neighbor, Random Forests, and Support Vector Machines classifiers." "I (the author) used the train_auto function of OpenCV, which splits the training set into a certain number of subsets, and perform cross-validation to optimize the parameters, by repeated training and testing using each time one of the subsets as testing set and the others as training set." Parameters used after optimization: C = 10 and epsilon = 0.01. 2015-07-07 02:43:08 -0500 commented question OpenCV SVM (RBF) low test accuracy at 10 % on MNIST I was initially expecting 98 % (1.77% error) from the OpenCV-Mnist-Report I read... Well anyway, I already edited it: Training-auto (with feature vector normalization) raised the accuracy to almost 80 %! 2015-07-07 02:39:38 -0500 edited question OpenCV SVM (RBF) low test accuracy at 10 % on MNIST I tried to train OpenCV SVM on MNIST dataset and I got weird results, i.e. test accuracy at 10 %. Any idea what went wrong? Thanks in advance. Here are the parameters I used: Ptr model = SVM::create(); model->setType(SVM::C_SVC); model->setKernel(SVM::RBF); model->setC(10); model->setGamma(0.01);  Training: model->train(tdata);  Testing: (from letter_recog.cpp sample)  static void test_and_save_classifier(const Ptr& model, const Mat& data, const Mat& responses, int ntrain_samples, int rdelta, const string& filename_to_save) { int i, nsamples_all = data.rows; double train_hr = 0, test_hr = 0; // compute prediction error on // train data[0 , ..., ntrain_samples-1]; and // test data[0 , ..., nsamples_all-1] before = static_cast(getTickCount()); for( i = 0; i < nsamples_all; i++ ) { Mat sample = data.row(i); // The method is used to predict the response for a new sample. // In case of a classification, the method returns the class label. float r = model->predict( sample ); /// sample is the row feature vector // Tally correct classifications // +1 if prediction is correct // +0 if prediction is wrong r = std::abs(r + rdelta - responses.at(i)) <= FLT_EPSILON ? 1.f : 0.f; if( i < ntrain_samples ) train_hr += r; else test_hr += r; } after = static_cast(getTickCount()); duration_in_ms = 1000.0*(after - before)/getTickFrequency(); cout << "Prediction for all data completed after "<< duration_in_ms <<" ms...\n"; cout << "Average prediction time per sample is "<< duration_in_ms/nsamples_all <<" ms.\n"; test_hr /= nsamples_all - ntrain_samples; train_hr = ntrain_samples > 0 ? train_hr/ntrain_samples : 1.; /// Note: 0 training samples here will give 100 % training error printf( "Recognition rate: train = %.2f%%, test = %.2f%%\n", train_hr*100., test_hr*100. ); if( !filename_to_save.empty() ) { model->save( filename_to_save ); } }  Test run: trainVecLabels.size() = 60000 trainVecLabels[0] = 5 testData.size() = 10000 testVecLabels.size() = 10000 testVecLabels[0] = 7 data.size() = [784 x 70000] responses.size() = [1 x 70000] Training the classifier ... Training completed after 11.1005 mins... Testing and saving ... Prediction for all data completed after 443715 ms... Average prediction time per sample is 6.33879 ms. Recognition rate: train = 24.92%, test = 10.09%  Training-auto without feature vector normalization: Ptr model = SVM::create(); model->setType(SVM::C_SVC); model->setKernel(SVM::RBF); model->trainAuto( tdata, 10 );  Result (10% accuracy):  [root@cobalt MNIST]# gcv SVM_MNIST.cpp -o SVM_MNIST [root@cobalt MNIST]# ./SVM_MNIST trainData.size() = 60000 init done opengl support available trainVecLabels.size() = 60000 trainVecLabels[0] = 5 testData.size() = 10000 testVecLabels.size() = 10000 testVecLabels[0] = 7 data.size() = [784 x 70000] responses.size() = [1 x 70000] Training the classifier ... Training completed after 3044.38 mins... Testing and saving ... Prediction for all data completed after 426744 ms... Average prediction time per sample is 6.09635 ms. Recognition rate: train = 24.92%, test = 10.09%  Training-auto (with feature vector normalization) raised the accuracy to almost 80 %! [root@cobalt MNIST]# gcv SVM_MNIST_Normalized.cpp -o SVM_MNIST_Normalized [root@cobalt MNIST]# ./SVM_MNIST_Normalized trainData.size() = 60000 trainVecLabels.size() = 60000 trainVecLabels[0] = 5 testData.size() = 10000 testVecLabels.size() = 10000 testVecLabels[0] = 7 data.size() = [784 x 70000] responses.size() = [1 x 70000] Training the classifier ... Training completed after 2356.62 mins... Testing and saving ... Prediction for all data completed after 950690 ms ... 2015-07-07 02:09:45 -0500 asked a question Any ideas on detecting and tracking hand touching the body with OpenCV? Problems: Detect the hand over the human body (Note: color is very similar). Localize the position of the touch Track the movement as the hand moves along the body. Here's a sample input image frame: I have tried a few possible solutions: Contour detection (It doesn't work! Or maybe I miss a few additional tricks?) Color Segmentation (It doesn't work! Similarity of color between the hand and skin is a big problem) Keypoints (e.g. SIFT, SURF, ORB, AKAZE)? (It might work! However, the hand movement itself is non-rigid thus, the comparison might end up inconsistent. Object Detection (e.g. Haar or LBP) (It might work! But then again, the non-rigidity of hand movement might cause a serious problem.) Background Subtraction/ Motion segmentation (It might work; but if the belly is bulky, then, there will be motion all over the region. Furthermore, the examiner's arm or body will be in motion as well....) More Machine Learning (RT, SVM, KNN, MLP etc.) (It might work? ) Does anyone (else) have experienced similar problems that involve the above issues? Thanks in advance. 2015-07-07 00:11:56 -0500 marked best answer Is there a 'c/cpp header file' alternative to OpenCV XML/YAML file storages for Real-time Object Detection in Embedded Systems, or Android NDK, etc. I have implemented object detection in Android NDK using jni and stevehavelka's assetbridge where the cascade is loaded as follows: Ex. if (cat_face_cascade.empty()){ sprintf( cat_face_cascade_path, "%s/%s", getenv("ASSETDIR"), "lbpcascade_frontalcatface.xml"); /* Load the face cascades */ if( !cat_face_cascade.load(cat_face_cascade_path) ){ LOGE("Error loading cat face cascade"); abort(); };  Full code here: Cat-detector-Android-jni However, I want to #include the xml cascade as a c/cpp header file to get rid of the parsing (not sure if this will help speed-up the frame rate, but i would like to try it anyway). Is there an OpenCV implementation somewhere similar to this idea? Ex. #ifndef CATDETECT_H #define CATDETECT_H /* ... * ... */ const int HEIGHT = 24; const int WIDTH = 24; // etc. #endif /* CATDETECT_H */  2015-07-07 00:11:55 -0500 commented answer Is there a 'c/cpp header file' alternative to OpenCV XML/YAML file storages for Real-time Object Detection in Embedded Systems, or Android NDK, etc. @sturkmen Thanks for your Answer. Indeed, it made the app much faster than before. By the way, I was playing with this last weekend and got real-time fps with multiple pyrDown(); similar to your idea of resizing the input image:  tmp = srcGray; scaled = tmp; for (uint8_t i = 0; i < downscale; i++){ pyrDown( tmp, scaled, Size( tmp.cols/2, tmp.rows/2 ) ); tmp = scaled; }  2015-07-07 00:01:57 -0500 received badge ● Enthusiast