使用Open CV更改Powerpoint中的幻灯片

时间：2015-09-22 12:58:30

标签： opencv

如何使用OpenCV或合适的图像处理工具更改照片中的幻灯片以更好地自动？我想它需要检测投影机，自动对比颜色，透视使其变得更好。

我使用photoshop手动转换

enter image description here

到

enter image description here

使用1）自动对比2）Photoshop中的透视变形

1 个答案:

答案 0 :(得分：1)

你可以：

1）将几乎为蓝色颜色的HSV图像阈值化以获得海报模板：

enter image description here

2）找到外部线及其交叉点：

enter image description here

3）应用透视变换：

enter image description here

4）应用一些颜色增强。在这里，我使用了Matlab imadjust的等价物。有关在OpenCV中移植的信息，请参阅here。

enter image description here

这里是完整的代码。评论应该澄清每一步。如果不清楚，请告诉我。

#include <opencv2\opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;


void imadjust(const Mat1b& src, Mat1b& dst, int tol = 1, Vec2i in = Vec2i(0, 255), Vec2i out = Vec2i(0, 255))
{
    // src : input CV_8UC1 image
    // dst : output CV_8UC1 imge
    // tol : tolerance, from 0 to 100.
    // in  : src image bounds
    // out : dst image buonds

    dst = src.clone();

    tol = max(0, min(100, tol));

    if (tol > 0)
    {
        // Compute in and out limits

        // Histogram
        vector<int> hist(256, 0);
        for (int r = 0; r < src.rows; ++r) {
            for (int c = 0; c < src.cols; ++c) {
                hist[src(r, c)]++;
            }
        }

        // Cumulative histogram
        vector<int> cum = hist;
        for (int i = 1; i < hist.size(); ++i) {
            cum[i] = cum[i - 1] + hist[i];
        }

        // Compute bounds
        int total = src.rows * src.cols;
        int low_bound = total * tol / 100;
        int upp_bound = total * (100 - tol) / 100;
        in[0] = distance(cum.begin(), lower_bound(cum.begin(), cum.end(), low_bound));
        in[1] = distance(cum.begin(), lower_bound(cum.begin(), cum.end(), upp_bound));

    }

    // Stretching
    float scale = float(out[1] - out[0]) / float(in[1] - in[0]);
    for (int r = 0; r < dst.rows; ++r)
    {
        for (int c = 0; c < dst.cols; ++c)
        {
            int vs = max(src(r, c) - in[0], 0);
            int vd = min(int(vs * scale + 0.5f) + out[0], out[1]);
            dst(r, c) = saturate_cast<uchar>(vd);
        }
    }
}


int main()
{
    // Load image
    Mat3b img = imread("path_to_image");
    Mat3b dbg = img.clone();    // Debug image

    // Convert to HSV
    Mat3b hsv;
    cvtColor(img, hsv, COLOR_BGR2HSV);

    // Threshold on HSV values
    Mat1b mask;
    inRange(hsv, Scalar(100, 140, 120), Scalar(110, 170, 200), mask);

    // Get the external boundaries
    Mat1b top(mask.rows, mask.cols, uchar(0));
    Mat1b bottom(mask.rows, mask.cols, uchar(0));
    Mat1b left(mask.rows, mask.cols, uchar(0));
    Mat1b right(mask.rows, mask.cols, uchar(0));

    for (int r = 0; r < mask.rows; ++r)
    {
        // Find first in row
        for (int c = 0; c < mask.cols; ++c)
        {
            if (mask(r, c))
            {
                left(r, c) = 255;
                break;
            }
        }

        // Find last in row
        for (int c = mask.cols - 1; c >= 0; --c)
        {
            if (mask(r, c))
            {
                right(r, c) = 255;
                break;
            }
        }
    }

    for (int c = 0; c < mask.cols; ++c)
    {
        // Find first in col
        for (int r = 0; r < mask.rows; ++r)
        {
            if (mask(r, c))
            {
                top(r, c) = 255;
                break;
            }
        }

        // Find last in col
        for (int r = mask.rows - 1; r >= 0; --r)
        {
            if (mask(r, c))
            {
                bottom(r, c) = 255;
                break;
            }
        }
    }

    // Find lines
    vector<Vec2f> linesTop, linesBottom, linesLeft, linesRight;
    HoughLines(top, linesTop, 1, CV_PI / 180.0, 100);
    HoughLines(bottom, linesBottom, 1, CV_PI / 180.0, 100);
    HoughLines(left, linesLeft, 1, CV_PI / 180.0, 100);
    HoughLines(right, linesRight, 1, CV_PI / 180.0, 100);


    // Find intersections

    Mat1b maskLines(mask.rows, mask.cols, uchar(0));

    if (linesTop.empty() || linesBottom.empty() || linesLeft.empty() || linesRight.empty())
    {
        cout << "No enough lines detected" << endl;
        return -1;
    }

    // Keep only the first line detected for each side
    vector<Vec2f> lines{ linesTop[0], linesBottom[0], linesLeft[0], linesRight[0] };

    for (size_t i = 0; i < lines.size(); i++)
    {
        float rho = lines[i][0], theta = lines[i][1];

        // Get 2 points on each line
        Point pt1, pt2;
        double a = cos(theta), b = sin(theta);
        double x0 = a*rho, y0 = b*rho;

        pt1.x = cvRound(x0 + 1000 * (-b));
        pt1.y = cvRound(y0 + 1000 * (a));
        pt2.x = cvRound(x0 - 1000 * (-b));
        pt2.y = cvRound(y0 - 1000 * (a));

        // Draw lines
        Mat1b maskCurrentLine(mask.rows, mask.cols, uchar(0));
        line(maskCurrentLine, pt1, pt2, Scalar(1), 1);
        maskLines += maskCurrentLine;

        line(dbg, pt1, pt2, Scalar(0, 0, 255), 3, CV_AA);
    }

    // Keep only intersections
    maskLines = maskLines > 1;

    // Get ordered set of vertices
    vector<Point2f> vertices;

    // Top left
    Mat1b tl(maskLines(Rect(0, 0, mask.cols / 2, mask.rows / 2)));
    for (int r = 0; r < tl.rows; ++r)
    {
        for (int c = 0; c < tl.cols; ++c)
        {
            if (tl(r, c))
            {
                vertices.push_back(Point2f(c, r));
            }
        }
    }

    // Top right
    Mat1b tr(maskLines(Rect(mask.cols / 2, 0, mask.cols / 2, mask.rows / 2)));
    for (int r = 0; r < tr.rows; ++r)
    {
        for (int c = 0; c < tr.cols; ++c)
        {
            if (tr(r, c))
            {
                vertices.push_back(Point2f(mask.cols / 2 + c, r));
            }
        }
    }

    // Bottom right
    Mat1b br(maskLines(Rect(mask.cols / 2, mask.rows / 2, mask.cols / 2, mask.rows / 2)));
    for (int r = 0; r < br.rows; ++r)
    {
        for (int c = 0; c < br.cols; ++c)
        {
            if (br(r, c))
            {
                vertices.push_back(Point2f(mask.cols / 2 + c, mask.rows / 2 + r));
            }
        }
    }

    // Bottom left
    Mat1b bl(maskLines(Rect(0, mask.rows / 2, mask.cols / 2, mask.rows / 2)));
    for (int r = 0; r < bl.rows; ++r)
    {
        for (int c = 0; c < bl.cols; ++c)
        {
            if (bl(r, c))
            {
                vertices.push_back(Point2f(c, mask.rows / 2 + r));
            }
        }
    }

    // Draw vertices
    for (int i = 0; i < vertices.size(); ++i)
    {
        circle(dbg, vertices[i], 7, Scalar(0,255,0), CV_FILLED);
    }


    // Init output image
    Mat3b result(img.rows, img.cols, Vec3b(0, 0, 0));

    // Output vertices
    vector<Point2f> verticesOut = { Point2f(0, 0), Point2f(img.cols, 0), Point2f(img.cols, img.rows), Point2f(0, img.rows) };

    // Get transformation
    Mat M = getPerspectiveTransform(vertices, verticesOut);
    warpPerspective(img, result, M, result.size());

    // Imadjust
    vector<Mat1b> planes;
    split(result, planes);

    for (int i = 0; i < planes.size(); ++i)
    {
        imadjust(planes[i], planes[i]);
    }

    Mat3b adjusted;
    merge(planes, adjusted);

    imshow("Result", result);
    imshow("Adjusted", adjusted);
    waitKey();

    return 0;
}
相关问题
最新问题