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Calculating Convolution sizes is something that I found particularly hard after understanding convolutions for the first time.

I couldn't remember the formula because I didn't understand its working exactly.

So here's my attempt to get some intuition behind the calculation.🔣👇


BTW if you haven't read the thread 🧵 on 1D, 2D, 3D CNN, you may want to check it out


First, observe the picture below🖼


The 2 x 2 filter slides over the
3 rows, 2 times and,
4 columns, 3 times

So, let's try subtracting the filter size first
3 - 2 = 1
4 - 2 = 2

Looks short, we'll need to compensate the 1 in both.
3 - 2 + 1 = 2
4 - 2 + 1 = 3

hence the formula so far becomes:


Now let's discuss padding0⃣

Zero padding makes it possible to get output equal to the input by adding extra columns.

It provides extra space for the sliding, making up for the lost space