c++ - OpenCV 中的稳健图像分割

Question

我正在尝试编写一个 OpenCV 程序来为其他人计算鱼卵。它目前对他们上传的图像进行归一化、模糊、阈值、膨胀、距离变换、再次阈值，然后找到轮廓(就像在典型的分水岭教程中一样)。

我遇到的问题是光照条件可能会有很大差异，因此即使使用自适应阈值，算法的准确性也会有很大差异。如果图像上存在渐变亮度，则效果似乎特别差。有时物体在背景下非常明亮，有时它们的亮度几乎相同。有没有什么特别有效的方法可以在不同的光照条件下找到物体？

示例图片:

Answer 1

因为任何大于 100 像素的东西都与您的图像无关，所以我会构造一个傅里叶带通滤波器来移除这些结构。

这是我使用的一种实现，基于 ImageJ 中的实现。在这个实现中，输入图像被镜像填充以减少边缘伪影。

static void GenerateBandFilter(thrust::host_vector<float>& filter, const BandPassSettings& band, const FrameSize& frame)
    {
        //From https://imagej.nih.gov/ij/plugins/fft-filter.html
        if (band.do_band_pass == false)
        {
            return;
        }
        if (frame.width != frame.height)
        {
            throw std::runtime_error("Frame height and width should be the same");
        }
        auto maxN = static_cast<int>(std::max(frame.width, frame.height));//todo make sure they are the same

        auto filterLargeC = 2.0f*band.max_dx / maxN;
        auto filterSmallC = 2.0f*band.min_dx / maxN;
        auto scaleLargeC = filterLargeC*filterLargeC;
        auto scaleSmallC = filterSmallC*filterSmallC;

        auto filterLargeR = 2.0f*band.max_dy / maxN;
        auto filterSmallR = 2.0f*band.min_dy / maxN;
        auto scaleLargeR = filterLargeR*filterLargeR;
        auto scaleSmallR = filterSmallR*filterSmallR;

        // loop over rows
        for (auto j = 1; j < maxN / 2; j++)
        {
            auto row = j * maxN;
            auto backrow = (maxN - j)*maxN;
            auto rowFactLarge = exp(-(j*j) * scaleLargeR);
            auto rowFactSmall = exp(-(j*j) * scaleSmallR);
            // loop over columns
            for (auto col = 1; col < maxN / 2; col++)
            {
                auto backcol = maxN - col;
                auto colFactLarge = exp(-(col*col) * scaleLargeC);
                auto colFactSmall = exp(-(col*col) * scaleSmallC);
                auto factor = (((1 - rowFactLarge*colFactLarge) * rowFactSmall*colFactSmall));
                filter[col + row] *= factor;
                filter[col + backrow] *= factor;
                filter[backcol + row] *= factor;
                filter[backcol + backrow] *= factor;
            }
        }
        auto fixy = [&](float t){return isinf(t) ? 0 : t; };
        auto rowmid = maxN * (maxN / 2);
        auto rowFactLarge = fixy(exp(-(maxN / 2)*(maxN / 2) * scaleLargeR));
        auto rowFactSmall = fixy(exp(-(maxN / 2)*(maxN / 2) *scaleSmallR));
        filter[maxN / 2] *= ((1 - rowFactLarge) * rowFactSmall);
        filter[rowmid] *= ((1 - rowFactLarge) * rowFactSmall);
        filter[maxN / 2 + rowmid] *= ((1 - rowFactLarge*rowFactLarge) * rowFactSmall*rowFactSmall); //
        rowFactLarge = fixy(exp(-(maxN / 2)*(maxN / 2) *scaleLargeR));
        rowFactSmall = fixy(exp(-(maxN / 2)*(maxN / 2) *scaleSmallR));
        for (auto col = 1; col < maxN / 2; col++){
            auto backcol = maxN - col;
            auto colFactLarge = exp(-(col*col) * scaleLargeC);
            auto colFactSmall = exp(-(col*col) * scaleSmallC);
            filter[col] *= ((1 - colFactLarge) * colFactSmall);
            filter[backcol] *= ((1 - colFactLarge) * colFactSmall);
            filter[col + rowmid] *= ((1 - colFactLarge*rowFactLarge) * colFactSmall*rowFactSmall);
            filter[backcol + rowmid] *= ((1 - colFactLarge*rowFactLarge) * colFactSmall*rowFactSmall);
        }
        // loop along column 0 and expanded_width/2
        auto colFactLarge = fixy(exp(-(maxN / 2)*(maxN / 2) * scaleLargeC));
        auto colFactSmall = fixy(exp(-(maxN / 2)*(maxN / 2) * scaleSmallC));
        for (auto j = 1; j < maxN / 2; j++) {
            auto row = j * maxN;
            auto backrow = (maxN - j)*maxN;
            rowFactLarge = exp(-(j*j) * scaleLargeC);
            rowFactSmall = exp(-(j*j) * scaleSmallC);
            filter[row] *= ((1 - rowFactLarge) * rowFactSmall);
            filter[backrow] *= ((1 - rowFactLarge) * rowFactSmall);
            filter[row + maxN / 2] *= ((1 - rowFactLarge*colFactLarge) * rowFactSmall*colFactSmall);
            filter[backrow + maxN / 2] *= ((1 - rowFactLarge*colFactLarge) * rowFactSmall*colFactSmall);
        }
        filter[0] = (band.remove_dc) ? 0 : filter[0];
    }

您可以在这里查看我使用它的代码:https://github.com/kandel3/DPM_PhaseRetrieval