在OpenCV的同一窗口中显示多个(2,3,4,...)图像

Question

我想在同一个窗口中显示2,3或更多图像.

我的问题是如何将第二张,第三张图像放在主图像的右侧(上方,左侧或上方).

我想使用OpenCV创建这样的东西.

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在此先感谢豪尔赫

Answer 1

我最近实现了这个.所以想分享它.它使用C++ API.代码是不言自明的(希望如此).

    /**
     * @brief makeCanvas Makes composite image from the given images
     * @param vecMat Vector of Images.
     * @param windowHeight The height of the new composite image to be formed.
     * @param nRows Number of rows of images. (Number of columns will be calculated
     *              depending on the value of total number of images).
     * @return new composite image.
     */
    cv::Mat makeCanvas(std::vector<cv::Mat>& vecMat, int windowHeight, int nRows) {
            int N = vecMat.size();
            nRows  = nRows > N ? N : nRows; 
            int edgeThickness = 10;
            int imagesPerRow = ceil(double(N) / nRows);
            int resizeHeight = floor(2.0 * ((floor(double(windowHeight - edgeThickness) / nRows)) / 2.0)) - edgeThickness;
            int maxRowLength = 0;

            std::vector<int> resizeWidth;
            for (int i = 0; i < N;) {
                    int thisRowLen = 0;
                    for (int k = 0; k < imagesPerRow; k++) {
                            double aspectRatio = double(vecMat[i].cols) / vecMat[i].rows;
                            int temp = int( ceil(resizeHeight * aspectRatio));
                            resizeWidth.push_back(temp);
                            thisRowLen += temp;
                            if (++i == N) break;
                    }
                    if ((thisRowLen + edgeThickness * (imagesPerRow + 1)) > maxRowLength) {
                            maxRowLength = thisRowLen + edgeThickness * (imagesPerRow + 1);
                    }
            }
            int windowWidth = maxRowLength;
            cv::Mat canvasImage(windowHeight, windowWidth, CV_8UC3, Scalar(0, 0, 0));

            for (int k = 0, i = 0; i < nRows; i++) {
                    int y = i * resizeHeight + (i + 1) * edgeThickness;
                    int x_end = edgeThickness;
                    for (int j = 0; j < imagesPerRow && k < N; k++, j++) {
                            int x = x_end;
                            cv::Rect roi(x, y, resizeWidth[k], resizeHeight);
                            cv::Size s = canvasImage(roi).size();
                            // change the number of channels to three
                            cv::Mat target_ROI(s, CV_8UC3);
                            if (vecMat[k].channels() != canvasImage.channels()) {
                                if (vecMat[k].channels() == 1) {
                                    cv::cvtColor(vecMat[k], target_ROI, CV_GRAY2BGR);
                                }
                            } else {             
                                vecMat[k].copyTo(target_ROI);
                            }
                            cv::resize(target_ROI, target_ROI, s);
                            if (target_ROI.type() != canvasImage.type()) {
                                target_ROI.convertTo(target_ROI, canvasImage.type());
                            }
                            target_ROI.copyTo(canvasImage(roi));
                            x_end += resizeWidth[k] + edgeThickness;
                    }
            }
            return canvasImage;
    }

这是样本输出.

Answer 2

您可以在OpenCV Wiki上找到答案:

https://github.com/opencv/opencv/wiki/DisplayManyImages

:-)

Answer 3

答案取决于您使用的接口(C或C++).一般工作流程是

• 创建一个足以容纳您的合成图像的图像(cv::Mat对于C++,IplImage*对于C)
• 将图像复制到大图像中
  • C++:使用Mat::Mat(const Mat& m, const Range& rowRange, const Range& colRange)构造函数cv::Mat指向原始窗口的子图像,然后使用该copyTo方法将小图像复制到大图像中
  • C:在大图像中设置ROI并将小图像复制到其中
• 显示您的大图像

Answer 4

或者只是使用:

Mat a, Mat b, Mat dst // a,b loaded

cv::hconcat(a, b, dst) // horizontal
cv::vconcat(a, b, dst) // vertical

Mat dst - > | a | b |

或用矢量做:

std::vector<cv::Mat> matrices = {
            a, b
    };
hconcat(matrices, dst);