batchnorm

相关公式

NCNN代码

int BatchNorm::forward_inplace(Mat& bottom_top_blob) const
{
    // a = bias - slope * mean / sqrt(var)
    // b = slope / sqrt(var)
    // value = b * value + a

    int w = bottom_top_blob.w;
    int h = bottom_top_blob.h;
    int size = w * h;

    const float* a_data_ptr = a_data;
    const float* b_data_ptr = b_data;
    #pragma omp parallel for
    for (int q=0; q<channels; q++)
    {
        float* ptr = bottom_top_blob.channel(q);

        float a = a_data_ptr[q];
        float b = b_data_ptr[q];

        for (int i=0; i<size; i++)
        {
            ptr[i] = b * ptr[i] + a;
        }
    }

    return 0;
}

参考资料

[1] Batch Normalization: Accelerating Deep Network Training by Reducing Internal Covariate Shift
[2] https://github.com/Tencent/ncnn