Keras - Fusion of a Dense Layer with a Convolution2D Layer
Asked Answered
A

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I want to make a custom layer which is supposed to fuse the output of a Dense Layer with a Convolution2D Layer.

The Idea came from this paper and here's the network:

The Network

the fusion layer tries to fuse the Convolution2D tensor (256x28x28) with the Dense tensor (256). here's the equation for it:

The Fusion Formula

y_global => Dense layer output with shape 256 y_mid => Convolution2D layer output with shape 256x28x28

Here's the description of the paper about the Fusion process:

capture3

I ended up making a new custom layer like below:

class FusionLayer(Layer):

    def __init__(self, output_dim, **kwargs):
        self.output_dim = output_dim
        super(FusionLayer, self).__init__(**kwargs)

    def build(self, input_shape):
        input_dim = input_shape[1][1]
        initial_weight_value = np.random.random((input_dim, self.output_dim))
        self.W = K.variable(initial_weight_value)
        self.b = K.zeros((input_dim,))
        self.trainable_weights = [self.W, self.b]

    def call(self, inputs, mask=None):
        y_global = inputs[0]
        y_mid = inputs[1]
        # the code below should be modified
        output = K.dot(K.concatenate([y_global, y_mid]), self.W)
        output += self.b
        return self.activation(output)

    def get_output_shape_for(self, input_shape):
        assert input_shape and len(input_shape) == 2
        return (input_shape[0], self.output_dim)

I think I got the __init__ and build methods right but I don't know how to concatenate y_global (256 dimesnions) with y-mid (256x28x28 dimensions) in the call layer so that the output would be the same as the equation mentioned above.

How can I implement this equation in the call method?

Thanks so much...

UPDATE: any other way to successfully integrate the data of these 2 layers is also acceptable for me... it doesn't exactly have to be the way mentioned in the paper but it needs to at least return an acceptable output...

Amoy answered 25/11, 2016 at 18:22 Comment(0)
A
3

I had to ask this question on the Keras Github page and someone helped me on how to implement it properly... here's the issue on github...

Amoy answered 4/12, 2016 at 16:36 Comment(0)
S
5

I was working on a project of Image Colorization and ended up facing a fusion layer problem then I found a model containing fusion Layer. Here it is Hope that solves your questions to some extent.

    embed_input = Input(shape=(1000,))
    encoder_input = Input(shape=(256, 256, 1,))

    #Encoder
    encoder_output = Conv2D(64, (3,3), activation='relu', padding='same', strides=2,
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_input)
    encoder_output = Conv2D(128, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_output)
    encoder_output = Conv2D(128, (3,3), activation='relu', padding='same', strides=2,
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_output)
    encoder_output = Conv2D(256, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_output)
    encoder_output = Conv2D(256, (3,3), activation='relu', padding='same', strides=2,
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_output)
    encoder_output = Conv2D(512, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_output)
    encoder_output = Conv2D(512, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_output)
    encoder_output = Conv2D(256, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(encoder_output)

    #Fusion
    fusion_output = RepeatVector(32 * 32)(embed_input)
    fusion_output = Reshape(([32, 32, 1000]))(fusion_output)
    fusion_output = concatenate([encoder_output, fusion_output], axis=3)
    fusion_output = Conv2D(256, (1, 1), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(fusion_output)

    #Decoder
    decoder_output = Conv2D(128, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(fusion_output)
    decoder_output = UpSampling2D((2, 2))(decoder_output)
    decoder_output = Conv2D(64, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(decoder_output)
    decoder_output = UpSampling2D((2, 2))(decoder_output)
    decoder_output = Conv2D(32, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(decoder_output)
    decoder_output = Conv2D(16, (3,3), activation='relu', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(decoder_output)
    decoder_output = Conv2D(2, (3, 3), activation='tanh', padding='same',
                            bias_initializer=TruncatedNormal(mean=0.0, stddev=0.05))(decoder_output)
    decoder_output = UpSampling2D((2, 2))(decoder_output)

    model = Model(inputs=[encoder_input, embed_input], outputs=decoder_output)

here is the source link: https://github.com/hvvashistha/Auto-Colorize

Spermatogonium answered 7/4, 2020 at 21:15 Comment(0)
A
3

I had to ask this question on the Keras Github page and someone helped me on how to implement it properly... here's the issue on github...

Amoy answered 4/12, 2016 at 16:36 Comment(0)
A
0

In my opinion implementing a new kind of layer is a way to complicated for this task. I strongly advise you to use the following layers:

in order to obtain the expected behaviour.

Atalanti answered 26/11, 2016 at 0:33 Comment(0)

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