获取图片中对象轮廓并替换白色

//
//  ViewController.m
//  opencvTest
//
//  Created by mac on 2020/7/16.
//  Copyright © 2020 mac. All rights reserved.
//
#import <opencv2/opencv.hpp>
#import <opencv2/imgcodecs/ios.h>
#import <opencv2/imgproc.hpp>
#import <opencv2/core/types.hpp>
#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.imageView = [[UIImageView alloc] initWithFrame:self.view.bounds];
    self.imageView.contentMode = UIViewContentModeScaleAspectFit;
    [self.view addSubview:self.imageView];
    self.imageView.image = [self.class opencvImageEdge:[UIImage imageNamed:@"888"]];
}

// 填充Holes
void fillHole(const cv::Mat srcBw, cv::Mat &dstBw)
{
    cv::Size m_Size = srcBw.size();
    cv::Mat Temp = cv::Mat::zeros(m_Size.height + 2, m_Size.width + 2, srcBw.type());//延展图像
    srcBw.copyTo(Temp(cv::Range(1, m_Size.height + 1), cv::Range(1, m_Size.width + 1)));

    floodFill(Temp, cv::Point(0, 0), cv::Scalar(255));

    cv::Mat cutImg;//裁剪延展的图像
    Temp(cv::Range(1, m_Size.height + 1), cv::Range(1, m_Size.width + 1)).copyTo(cutImg);

    dstBw = srcBw | (~cutImg);
}

/// 图片边缘检测
/// @param srcImage 原始图片
+ (UIImage *)opencvImageEdge:(UIImage *)srcImage {
    //加载图片
    cv::Mat mat_image_src;
    UIImageToMat(srcImage, mat_image_src);
    
    //创建和mat_image_src同样大小的OpenCV图片(Mat)
    cv::Mat mat_image_dst;
    mat_image_dst.create(mat_image_src.size(), mat_image_src.type());
    
    //将图片进行灰度处理(图片变为灰色)
    cv::Mat mat_image_gray;
    cvtColor(mat_image_src, mat_image_gray, cv::COLOR_BGR2GRAY);
    
    //使用3*3内核来降噪处理
    cv::Mat mat_image_edge;
    blur(mat_image_gray, mat_image_edge, cv::Size2i(3, 3));
    
    //进行Canny算子处理
    // 30 20对应的参数可做调整，对轮廓的获取有很大的帮助
//    Canny(mat_image_edge, mat_image_edge, 30, 20, 3);
    Canny(mat_image_edge, mat_image_edge, 30, 20, 3);
    
    //【4】膨胀操作, 填充边缘缝隙
    cv::Mat element = getStructuringElement(cv::MORPH_RECT, cv::Size(3, 3));
    for (int i = 0;i < 3;i++) {
        dilate(mat_image_edge, mat_image_edge, element);
    }
    
    // 【5】Holes填充
    for (int i = 0;i < 10;i++) // 填充10次
    {
        fillHole(mat_image_edge, mat_image_edge);
    }
    
    //将OpenCV图片->转成iOS图片
    return MatToUIImage(mat_image_edge);
}


@end

参照文章地址：

https://blog.csdn.net/guguant/article/details/54428817

https://github.com/EdenmsX/OpenCVTest/blob/master/OpenCVTestDemo/OpenCVTestDemo/OpenCVImageUtils.mm

其他

https://www.cnblogs.com/mangoroom/p/11128738.html opencv滤镜用法

https://zhuanlan.zhihu.com/p/85813603

https://www.jianshu.com/p/3aa810b35a5d