OpenCV每日函数图像过滤模块 (15) morphologyEx函数

一、概述

执行高级形态变换。函数 cv::morphologyEx 可以使用腐蚀和膨胀作为基本操作来执行高级形态变换。任何操作都可以就地完成。在多通道图像的情况下，每个通道都是独立处理的。

支持的操作如下表

Enumerator
MORPH_ERODE Python: cv.MORPH_ERODE	ERODE 腐蚀
MORPH_DILATE Python: cv.MORPH_DILATE	DILATE 膨胀
MORPH_OPEN Python: cv.MORPH_OPEN	an opening operation 开运算 dst=open(src,element)=dilate(erode(src,element))
MORPH_CLOSE Python: cv.MORPH_CLOSE	a closing operation 闭运算 dst=close(src,element)=erode(dilate(src,element))
MORPH_GRADIENT Python: cv.MORPH_GRADIENT	a morphological gradient 形态学梯度 dst=morph_grad(src,element)=dilate(src,element)−erode(src,element)
MORPH_TOPHAT Python: cv.MORPH_TOPHAT	"top hat" 顶帽 dst=tophat(src,element)=src−open(src,element)
MORPH_BLACKHAT Python: cv.MORPH_BLACKHAT	"black hat" 黑帽 dst=blackhat(src,element)=close(src,element)−src
MORPH_HITMISS Python: cv.MORPH_HITMISS	"hit or miss" .- Only supported for CV_8UC1 binary images. A tutorial can be found in the documentation 击中击不中

二、morphologyEx函数

1、函数原型

cv::morphologyEx (InputArray src, OutputArray dst, int op, InputArray kernel, Point anchor=Point(-1,-1), int iterations=1, int borderType=BORDER_CONSTANT, const Scalar &borderValue=morphologyDefaultBorderValue())

2、参数详解

src	源图像。通道的数量可以是任意的。深度应该是 CV_8U、CV_16U、CV_16S、CV_32F 或 CV_64F 之一。
dst	与源图像具有相同大小和类型的目标图像。
op	形态学操作的类型，请参阅 MorphTypes
kernel	结构元素。它可以使用 getStructuringElement 创建。
anchor	与内核的锚定位置。负值表示锚点位于内核中心。
iterations	应用腐蚀和膨胀的次数。
borderType	像素外推法，请参阅 BorderTypes。不支持 BORDER_WRAP。
borderValue	边界不变的情况下的边界值。默认值具有特殊含义。

三、OpenCV源码

1、源码路径

opencv\modules\imgproc\src\morph.dispatch.cpp

2、源码代码

void morphologyEx( InputArray _src, OutputArray _dst, int op,
                       InputArray _kernel, Point anchor, int iterations,
                       int borderType, const Scalar& borderValue )
{
    CV_INSTRUMENT_REGION();

    CV_Assert(!_src.empty());

    Mat kernel = _kernel.getMat();
    if (kernel.empty())
    {
        kernel = getStructuringElement(MORPH_RECT, Size(3,3), Point(1,1));
    }
#ifdef HAVE_OPENCL
    Size ksize = kernel.size();
    anchor = normalizeAnchor(anchor, ksize);

    CV_OCL_RUN(_dst.isUMat() && _src.dims() <= 2 && _src.channels() <= 4 &&
        anchor.x == ksize.width >> 1 && anchor.y == ksize.height >> 1 &&
        borderType == cv::BORDER_CONSTANT && borderValue == morphologyDefaultBorderValue(),
        ocl_morphologyEx(_src, _dst, op, kernel, anchor, iterations, borderType, borderValue))
#endif

    Mat src = _src.getMat(), temp;
    _dst.create(src.size(), src.type());
    Mat dst = _dst.getMat();

#if !IPP_DISABLE_MORPH_ADV
    //CV_IPP_RUN_FAST(ipp_morphologyEx(op, src, dst, kernel, anchor, iterations, borderType, borderValue));
#endif

    switch( op )
    {
    case MORPH_ERODE:
        erode( src, dst, kernel, anchor, iterations, borderType, borderValue );
        break;
    case MORPH_DILATE:
        dilate( src, dst, kernel, anchor, iterations, borderType, borderValue );
        break;
    case MORPH_OPEN:
        erode( src, dst, kernel, anchor, iterations, borderType, borderValue );
        dilate( dst, dst, kernel, anchor, iterations, borderType, borderValue );
        break;
    case MORPH_CLOSE:
        dilate( src, dst, kernel, anchor, iterations, borderType, borderValue );
        erode( dst, dst, kernel, anchor, iterations, borderType, borderValue );
        break;
    case MORPH_GRADIENT:
        erode( src, temp, kernel, anchor, iterations, borderType, borderValue );
        dilate( src, dst, kernel, anchor, iterations, borderType, borderValue );
        dst -= temp;
        break;
    case MORPH_TOPHAT:
        if( src.data != dst.data )
            temp = dst;
        erode( src, temp, kernel, anchor, iterations, borderType, borderValue );
        dilate( temp, temp, kernel, anchor, iterations, borderType, borderValue );
        dst = src - temp;
        break;
    case MORPH_BLACKHAT:
        if( src.data != dst.data )
            temp = dst;
        dilate( src, temp, kernel, anchor, iterations, borderType, borderValue );
        erode( temp, temp, kernel, anchor, iterations, borderType, borderValue );
        dst = temp - src;
        break;
    case MORPH_HITMISS:
        CV_Assert(src.type() == CV_8UC1);
        if(countNonZero(kernel) <=0)
        {
            src.copyTo(dst);
            break;
        }
        {
            Mat k1, k2, e1, e2;
            k1 = (kernel == 1);
            k2 = (kernel == -1);

            if (countNonZero(k1) <= 0)
                e1 = Mat(src.size(), src.type(), Scalar(255));
            else
                erode(src, e1, k1, anchor, iterations, borderType, borderValue);

            if (countNonZero(k2) <= 0)
                e2 = Mat(src.size(), src.type(), Scalar(255));
            else
            {
                Mat src_complement;
                bitwise_not(src, src_complement);
                erode(src_complement, e2, k2, anchor, iterations, borderType, borderValue);
            }
            dst = e1 & e2;
        }
        break;
    default:
        CV_Error( CV_StsBadArg, "unknown morphological operation" );
    }
}