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fanfuhan OpenCV 教學038 ~ opencv-038-拉普拉斯金字塔 – jashliao部落格

fanfuhan OpenCV 教學038 ~ opencv-038-拉普拉斯金字塔


資料來源: https://fanfuhan.github.io/

https://fanfuhan.github.io/2019/04/11/opencv-038/

GITHUB:https://github.com/jash-git/fanfuhan_ML_OpenCV


知識點:

對輸入圖像實現金字塔的reduce操作就會生成不同分辨率的圖像、對這些圖像進行金字塔expand操作,然後使用reduce減去expand之後的結果就會得到圖像拉普拉斯金字塔圖像。
舉例如下:
輸入圖像G(0)
金字塔reduce操作生成G(1), G(2), G(3)
拉普拉斯金字塔:
L0 = G(0)-expand(G(1))
L1 = G (1)-expand(G(2))
L2 = G(2)–expand(G(3))
G(0)減去expand(G(1))得到的結果就是兩次高斯模糊輸出的不同,所以L0稱為DOG(高斯不同)、它約等於LOG所以又稱為拉普拉斯金字塔。所以要求的圖像的拉普拉斯金字塔,首先要進行金字塔的reduce操作,然後在通過expand操作,最後相減得到拉普拉斯金字塔圖像。

C++

#include 
#include 

using namespace std;
using namespace cv;

void pyramid_up(Mat &image, vector &pyramid_images, int level);

void laplaian_demo(vector &pyramid_images, Mat &image);

/*
 * 拉普拉斯金字塔
 */
int main() {
    Mat src = imread("../images/test1.jpg");
    if (src.empty()) {
        cout << "could not load image.." << endl;
    }
    imshow("input", src);

    vector p_images;
    pyramid_up(src, p_images, 2);
    laplaian_demo(p_images, src);

    waitKey(0);
    return 0;
}

void laplaian_demo(vector &pyramid_images, Mat &image) {
    for (int i = pyramid_images.size() - 1; i > -1; --i) {
        Mat dst;
        if (i - 1 < 0) {
            pyrUp(pyramid_images[i], dst, image.size());
            subtract(image, dst, dst);
            dst = dst + Scalar(127, 127, 127);# 调亮度, 实际中不能这么用
            imshow(format("laplaian_layer_%d", i), dst);
        } else {
            pyrUp(pyramid_images[i], dst, pyramid_images[i-1].size());
            subtract(pyramid_images[i - 1], dst, dst);
            dst = dst + Scalar(127, 127, 127);
            imshow(format("laplaian_layer_%d", i), dst);
        }
    }
}

void pyramid_up(Mat &image, vector &pyramid_images, int level) {
    Mat temp = image.clone();
    Mat dst;
    for (int i = 0; i < level; ++i) {
        pyrDown(temp, dst);
        //imshow(format("pyramid_up_%d", i), dst);
        temp = dst.clone();
        pyramid_images.push_back(temp);
    }
}

Python

import cv2 as cv
import numpy as np


def laplaian_demo(pyramid_images):
    level = len(pyramid_images)
    for i in range(level-1, -1, -1):
        if (i-1) < 0:
            h, w = src.shape[:2]
            expand = cv.pyrUp(pyramid_images[i], dstsize=(w, h))
            lpls = cv.subtract(src, expand) + 127
            cv.imshow("lpls_" + str(i), lpls)
        else:
            h, w = pyramid_images[i-1].shape[:2]
            expand = cv.pyrUp(pyramid_images[i], dstsize=(w, h))
            lpls = cv.subtract(pyramid_images[i-1], expand) + 127
            cv.imshow("lpls_"+str(i), lpls)


def pyramid_up(image, level=3):
    temp = image.copy()
    # cv.imshow("input", image)
    pyramid_images = []
    for i in range(level):
        dst = cv.pyrDown(temp)
        pyramid_images.append(dst)
        # cv.imshow("pyramid_up_" + str(i), dst)
        temp = dst.copy()
    return pyramid_images


src = cv.imread("D:/images/master.jpg")
cv.namedWindow("input", cv.WINDOW_AUTOSIZE)
cv.imshow("input", src)
# pyramid_up(src)
laplaian_demo(pyramid_up(src))

cv.waitKey(0)
cv.destroyAllWindows()



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