So I am building a keras sequential model in which the last output layer is an Upsampling2D layer & I need to feed the input image to that output layer to do a simple operation and return the output, any ideas?
EDIT :
The model mentioned before is the generator of a GAN model in which I need to add the input image to the output of the generator before feeding it to the discriminator
1.You can define a backbone model using inputs of pre-trained model and the outputs of the last layer before the output layer of pre-trained model
2.Base on that backbone model, defined new model have that new skip connection and the output layer as same as pre-trained model
3.Set the weights of output layer in new model to equal to weights of output layer in pre-trained model, using: new_model.layers[-1].set_weights(pre_model.layers[-1].get_weights())
Here is one good article about Adding Layers to the middle of a pre-trained network whithout invalidating the weights
So for the future reference, I solved it by using lambda layers as follow :
# z is the input I needed to use later on with the generator output to perform a certain function
generated_image = self.generator(z)
generated_image_modified=tf.keras.layers.Concatenate()([generated_image,z])
# with x[...,variable_you_need_range] you can access the input we just concatenated in your train loop
lambd = tf.keras.layers.Lambda(lambda x: your_function(x[...,2:5],x[...,:2]))(generated_image_modified)
full_model = self.discriminator(lambd)
self.combined = Model(z,outputs = full_model)