Thanks. Actually in this model I don’t know the nature of the additional channel, but in another model where I got nearly the same error, the owner answered me:“input raw images should be 4-channel Bayer images ([R, Gr, B, Gb]), not the 3-channel”, this is criptyc for me.
So, the BAYER CHANNEL is an alpha channel? I mean, if I add an alpha channel and the training is performed with the bayer channel, is it the same?
P.S. I tried to add the alpha channel, but the result (this is an enhancement image code) is an image with a huge PURPLE  dominant.