profile pic
⌘ '
raccourcis clavier

See also: this one assignment on CNN

how can we exploit sparsity and locality?

think of sparse connectivity rather than full connectivity

where we exploiting invariance, it might be useful in other parts of the image as well

convolution

accept volume of size W1×H1×D1W_1 \times H_1 \times D_1 with four hyperparameters

  • filters KK
  • spatial extent FF
  • stride SS
  • amount of zero padding PP

calculation

produces a volume of size W2×H2×D2W_2 \times H_2 \times D_2 where:

  • W2=W1F+2PS+1W_2 = \frac{W_1 - F + 2P}{S} + 1
  • H2=H1F+2PS+1H_2 = \frac{H_1 - F + 2P}{S} + 1
  • D2=KD_2 = K

1D convolution:

y=(xw)y(i)=tx(t)w(it)\begin{aligned} y &= (x*w) \\ y(i) &= \sum_{t}x(t)w(i-t) \end{aligned}

2D convolution:

y=(xw)y(i,j)=t1t2x(t1,t2)w(it1,jt2)\begin{aligned} y &= (x*w) \\ y(i,j) &= \sum_{t_1} \sum_{t_2} x(t_1, t_2) w(i-t_1,j-t_2) \end{aligned}

max pooling

idea to reduce number of parameters

batchnorm

xj=[x1j,,xdj]x^{j} = [x_1^j,\ldots,x_d^j]

Batch X=[(x1)T(xb)T]TX = [(x^1)^T \ldots (x^b)^T]^T