How to define focal loss in train_val.prototxt, two classes with softmax?

[wvinzh]

I'm using Focal Loss to train a two-class model.
my prototxt is like this:
layer {
bottom: "pool5"
top: "fc2"
name: "fc2"
type: "InnerProduct"
inner_product_param {
num_output: 2
}
}
layer {
bottom: "fc2"
top: "prob"
name: "prob"
type: "Softmax"
}

layer {
name: "loss_cls"
type: "FocalLoss"
bottom: "prob"
bottom: "label"
propagate_down: 1
propagate_down: 0
top: "loss_cls"
include { phase: TRAIN }
loss_weight: 1
loss_param { ignore_label: -1 normalize: true }
focal_loss_param { alpha: 0.5 gamma: 2 }
}

but it went wrong :
bottom[0]->count() == bottom[1]->count() (16 vs. 8) SIGMOID_CROSS_ENTROPY_LOSS layer inputs must have the same count.

I think maybe this Focal loss is using simoid, so how can i use it with softmax??

thanks!

[lyj0823]

Have you solved this problem,please help me ,thanks!

[JackyWang-001]

Delete the Softmax layer, beacuse it is used in deploy.prototxt, and change bottom: "prob"to bottom: "fc2" in FocalLoss layer.

[ngunauj]

why ignore label: -1 ??

[1343464520]

@wvinzh @lyj0823 @Jacky3213 also have this problem. And i try to change the num_output of fc layer from 2 to 1. It does work, but the acc is very low...just 60%... So, how do you solve it? Please help, Thanks!