Demo Feature Extraction

In this example we extract 3 features from the input image Original Image.jpg. These features are NDVI, Variance of intensity and saturation. The features are calculated for every pixel of the input image and thus are represented as images of the same resolution as the input one. It is often convenient to have a set of features in form of one multi-channel image. For storing such a multi-channel image is usually split into a number of 3-channels RGB images. Hence, for sake of simplicity, we extract only 3 features in this example.

Input		Output
Original Image.jpg		Resulting Feature Vector

#include "FEX.h"
using namespace DirectGraphicalModels;

int main()
{
    if (argc != 3) {
        print_help(argv[0]);
        return 0;
    }

    Mat img = imread(argv[1], 1);
    fex::CCommonFeatureExtractor fExtractor(img);

    Mat coord = fex::CCoordinate::get(img);

    // Extracting 3 features
    Mat ndvi        = fExtractor.getNDVI(10).get();                                         // NDVI feature
    Mat variance    = fExtractor.getIntensity(CV_RGB(0.0, 0.5, 0.5)).getVariance().get();   // Variance of intensity feature
    Mat saturation  = fExtractor.getSaturation().invert().get();                            // Inverted saturation feature

    // Storing 3 features in a 3 channel RGB image
    Mat         featureImg;
    vec_mat_t   channels;
    channels.push_back(ndvi);           // blue channel
    channels.push_back(variance);       // green channel
    channels.push_back(saturation);     // red channel
    merge(channels, featureImg);

    imwrite(argv[2], featureImg);
    return 0;
}