im2col.hpp

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#ifndef __OPENCV_DNN_LAYERS_IM2COL_HPP__
#define __OPENCV_DNN_LAYERS_IM2COL_HPP__

namespace cv
{
namespace dnn
{

template <typename Dtype>
void im2col_cpu(const Dtype* data_im,
                int channels, int height, int width,
                int kernel_h, int kernel_w,
                int pad_h, int pad_w,
                int stride_h, int stride_w,
                Dtype* data_col)
{
    int height_col = (height + 2 * pad_h - kernel_h) / stride_h + 1;
    int width_col = (width + 2 * pad_w - kernel_w) / stride_w + 1;
    int channels_col = channels * kernel_h * kernel_w;
    for (int c = 0; c < channels_col; ++c) {
        int w_offset = c % kernel_w;
        int h_offset = (c / kernel_w) % kernel_h;
        int c_im = c / kernel_h / kernel_w;
        for (int h = 0; h < height_col; ++h) {
            for (int w = 0; w < width_col; ++w) {
                int h_pad = h * stride_h - pad_h + h_offset;
                int w_pad = w * stride_w - pad_w + w_offset;
                if (h_pad >= 0 && h_pad < height && w_pad >= 0 && w_pad < width)
                    data_col[(c * height_col + h) * width_col + w] =
                    data_im[(c_im * height + h_pad) * width + w_pad];
                else
                    data_col[(c * height_col + h) * width_col + w] = 0;
            }
        }
    }
}

template <typename Dtype>
void col2im_cpu(const Dtype* data_col,
                int channels, int height, int width,
                int patch_h, int patch_w,
                int pad_h, int pad_w,
                int stride_h, int stride_w,
                Dtype* data_im)
{
    memset(data_im, 0, height * width * channels * sizeof(Dtype));

    int height_col = (height + 2 * pad_h - patch_h) / stride_h + 1;
    int width_col = (width + 2 * pad_w - patch_w) / stride_w + 1;
    int channels_col = channels * patch_h * patch_w;

    for (int c = 0; c < channels_col; ++c)
    {
        int w_offset = c % patch_w;
        int h_offset = (c / patch_w) % patch_h;
        int c_im = c / patch_h / patch_w;

        for (int h = 0; h < height_col; ++h)
        {
            for (int w = 0; w < width_col; ++w)
            {
                int h_pad = h * stride_h - pad_h + h_offset;
                int w_pad = w * stride_w - pad_w + w_offset;

                if (h_pad >= 0 && h_pad < height && w_pad >= 0 && w_pad < width)
                    data_im[(c_im * height + h_pad) * width + w_pad] +=
                    data_col[(c * height_col + h) * width_col + w];
            }
        }
    }
}

#ifdef HAVE_OPENCL
void im2col_ocl(UMat &img,
                int channels, int height, int width,
                int kernel_h, int kernel_w,
                int pad_h, int pad_w,
                int stride_h, int stride_w,
                UMat &col);
#endif

}
}

#endif