A filter slides over an image
Move a 5×5 filter across a 32×32×3 image and see exactly which pixels feed each cell of the activation map.
This scene needs WebGL. The controls and numbers beside it still work.
drag to orbit
Reading the scene: more ink on a sheet means a larger value, and the map is shaded relative to its own largest value. On the filter face, blue is a positive weight and orange a negative one. Simplified: each preset repeats one F×F pattern on all three channels at one third weight, the bias is 0, and padding adds zeros.
What to look for
- One filter, one map. The same weights are reused at every stop, so the parameter count depends on F and the number of filters and never on the image size. This page shows one filter. A layer with six filters stacks six such maps.
- ReLU keeps one polarity. With the vertical edge filter, the left side of each shape lights up. The right side gives a negative sum, and ReLU clips it to zero.
- Shift in, shift out. The map keeps the layout of the image: the square sits top left in both. Convolution is translation equivariant. The rough invariance to small shifts comes later, from pooling.