confused bout the size of x and offsets

[Damax18]

Thanks for your sharing code, and i'm cofused about the size of each x and offsets.
If the shape of x is (b,c,h,w), kernel_size is 3, padding is 1, the offsets should be (b,18,h,w) and the x_offset (b,c,3h,3w) is the deformable form of original input x? Finally, the output still is (b,c,h,w) after a convolution layer(kernel_size is 3,no padding and stride is 3)?
Please point out the mistake if my understanding is wrong.
Thanks you again and look forward to your reply.