upsampling: There are two main methods for upsampling in the generator. Transposed convolution is faster, but can lead to checkerboard artifacts, which can be reduced by using a kernel size that is divisible with the stride (recommended kernel size is 4 for a stride of 2). Upsampling + standard convolution can have slightly lower quality, but checkerboard artifacts are not an issue. I recommend using nearest-neighbor interpolation over bilinear for it.