I always thought of this so-called “progressive blur” as simply being a Gaussian blur with a kernel gradient mask whose channel range was used as the coefficien

I always thought of this so-called “progressive blur” as simply being a Gaussian blur with a kernel gradient mask whose channel range was used as the coefficient for the kernel size for a given pixel. So where the kernel gradient mask is 1, you multiply this by the desired max radius blur, down to 0, which represents a radius blur of 0. Edit: Why downvote this? It’s literally how you implement it.