如何在 SuperpixelSLIC 中找到段的唯一标签

Question

我正在使用 cv::ximgproc::SuperpixelSLIC opencv c++ 生成图像片段。我希望每个段标签都是唯一的。这是我的代码。

Mat segmentImage() {
    int num_iterations = 4;
    int prior = 2;
    bool double_step = false;
    int num_levels = 10;
    int num_histogram_bins = 5;

    int width, height;

    width = h1.size().width;
    height = h1.size().height;

    seeds = createSuperpixelSLIC(h1);

    Mat mask;

    seeds->iterate(num_iterations);

    Mat labels;
    seeds->getLabels(labels);
    for (int i = 0; i < labels.rows; i++) {
        for (int j = 0; j < labels.cols; j++) {
            if (labels.at<int>(i, j) == 0)
                cout << i << " " << j << " " << labels.at<int>(i, j) << endl;

        }
    }
    ofstream myfile;
    myfile.open("label.txt");
    myfile << labels;
    myfile.close();

    seeds->getLabelContourMask(mask, false);
    h1.setTo(Scalar(0, 0, 255), mask);

    imshow("result", h1);
    imwrite("result.png", h1);
    return labels;
}

在label.txt文件中，我观察到标签0被赋予了两个段（即段包括像素（0,0）和像素（692,442）。这两个段很远。

这是正常现象还是我的代码不正确。请帮我找到每个细分市场的唯一标签。

Answer 1

您本质上需要的是连通分量算法。在不知道您使用的确切 SLIC 实现的情况下，SLIC 通常会产生断开连接的超像素，即具有相同标签的断开连接的片段。我使用的一个简单解决方案是此处的连通分量算法形式：https://github.com/davidstutz/matlab-multi-label-connected-components (originally from here: http://xenia.media.mit.edu/~rahimi/connected/)。请注意，此存储库包含一个 MatLab 包装器。在您的情况下，您只需要 connected_components.h 和以下代码：

#include "connected_components.h"
// ...

void relabelSuperpixels(cv::Mat &labels) {

    int max_label = 0;
    for (int i = 0; i < labels.rows; i++) {
        for (int j = 0; j < labels.cols; j++) {
            if (labels.at<int>(i, j) > max_label) {
                max_label = labels.at<int>(i, j);
            }
        }
    }

    int current_label = 0;
    std::vector<int> label_correspondence(max_label + 1, -1);

    for (int i = 0; i < labels.rows; i++) {
        for (int j = 0; j < labels.cols; j++) {
            int label = labels.at<int>(i, j);

            if (label_correspondence[label] < 0) {
                label_correspondence[label] = current_label++;
            }

            labels.at<int>(i, j) = label_correspondence[label];
        }
    }
}

int relabelConnectedSuperpixels(cv::Mat &labels) {

    relabelSuperpixels(labels);

    int max = 0;
    for (int i = 0; i < labels.rows; ++i) {
        for (int j = 0; j < labels.cols; ++j) {
            if (labels.at<int>(i, j) > max) {
                max = labels.at<int>(i, j);
            }
        }
    }

    ConnectedComponents cc(2*max);

    cv::Mat components(labels.rows, labels.cols, CV_32SC1, cv::Scalar(0));
    int component_count = cc.connected<int, int, std::equal_to<int>, bool>((int*) labels.data, (int*) components.data, labels.cols, 
            labels.rows, std::equal_to<int>(), false);

    for (int i = 0; i < labels.rows; i++) {
        for (int j = 0; j < labels.cols; j++) {
            labels.at<int>(i, j) = components.at<int>(i, j);
        }
    }

    // component_count would be the NEXT label index, max is the current highest!
    return component_count - max - 1;
}

在获得的标签上，运行 relabelConnectedSuperpixels.

如何在 SuperpixelSLIC 中找到段的唯一标签

How to find unique labels for segments in SuperpixelSLIC

c++

opencv

opencv3.0

superpixels