About the input channels

[tonytonglt]

Hi. As you mentioned in the paper, you changed the input channels from 3 to 9. However, when I look into your code, in models.py line 53, I found that num_channels = 3 + 6 + 2. Does it mean input channel of 11? What does 3, 6 and 2 indicate? Looking forward to your reply. Thanks.

[99991]

I think the channels are distributed like this:

• 3 channels: This is the input image (group normalized).
• 6 channels: Some kind of approximate alpha matte computed from the distance to the foreground and background of the trimap. See https://github.com/MarcoForte/FBA_Matting/issues/17 for more details.
• 2 channels: The foreground and background channels of the trimap.