Classification problem using features with unequal sizes
I am not sure if what I am gonna say is totally correct but you could try it. So instead of treating each of the pixels as part of one feature, you could append everything to make one array. That array would be of size N+3+1. So this would be the size of one row in data matrix and further you could provide weightage to the elements. Like if pixels are more important then mulitply them by some factor. One problem that I see in dealing with this might be standardization of data matrix.