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> We show that passing input points through a simple Fourier feature mapping enables a multilayer perceptron (MLP) to learn high-frequency functions in low-dime
by memexy 6y ago
> We show that passing input points through a simple Fourier feature mapping enables a multilayer perceptron (MLP) to learn high-frequency functions in low-dimensional problem domains. These results shed light on recent advances in computer vision and graphics that achieve state-of-the-art results by using MLPs to represent complex 3D objects and scenes. Using tools from the neural tangent kernel (NTK) literature, we show that a standard MLP fails to learn high frequencies both in theory and in practice. To overcome this spectral bias, we use a Fourier feature mapping to transform the effective NTK into a stationary kernel with a tunable bandwidth. We suggest an approach for selecting problem-specific Fourier features that greatly improves the performance of MLPs for low-dimensional regression tasks relevant to the computer vision and graphics communities.
I don't know what some of those words mean but had been wondering why neural networks did not have Fourier transform blocks. Convolutions become point-wise multiplication when the functions are decomposed into their frequency components so it seemed like an obvious thing to do. It's good to see I wasn't insane.
> In this paper, we train MLP networks to learn low dimensional functions, such as the function defined by an image that maps each (x, y) pixel coordinate to an output (r, g, b) color. A standard MLP is not able to learn such functions (blue border image). Simply applying a Fourier feature mapping to the input (x, y) points before passing them to the network allows for rapid convergence (orange border image).
Technically a Fourier feature mapping is not a Fourier transform but the idea of decomposing functions into their frequency components before feeding them into a neural network seems to hold up.
Fun paper. Thanks for posting.