Everything Is a Function

The machine never sees your drawing. It sees 784 numbers, and a prediction is just arithmetic on them. Draw a digit and watch the picture disappear.

1 You draw

2 The machine gets pixels…

Hover the grid. Every cell is just a brightness number between 0 and 1.

3 A function fires

f(x) = softmax(W·x + b)

Draw a digit to start.

What f is actually looking for

Each output score has its own 784 weights, shown here as images. Orange pixels add to that digit’s score when inked, blue pixels subtract. The model is scoring your drawing against ten fuzzy stencils. Nobody drew these. That’s part 2.