questions about the last activation function

[HaoDot]

HI! E2VID is a great work, thx for sharing! It confuses me a lot about the last activation function for recurrent architecture, which is sigmoid. As far as I am concerned, sigmoid was often used at Binary Classification or binary image prediction where it outputs images consisting of one or zero in intensity dimension. As for video reconstruction, the final output's intensity ranges from 0 to 255. Inspite of scaling the output to 0-255, the most of intensity is around half of 255. It is a great honor to get your reply, thx a lot.