Python keras.layers.convolutional.Conv2D() Examples

def build_generator(self):

        model = Sequential()

        model.add(Dense(128 * 7 * 7, activation="relu", input_dim=self.latent_dim))
        model.add(Reshape((7, 7, 128)))
        model.add(BatchNormalization(momentum=0.8))
        model.add(UpSampling2D())
        model.add(Conv2D(128, kernel_size=3, padding="same"))
        model.add(Activation("relu"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(UpSampling2D())
        model.add(Conv2D(64, kernel_size=3, padding="same"))
        model.add(Activation("relu"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Conv2D(1, kernel_size=3, padding="same"))
        model.add(Activation("tanh"))

        model.summary()

        noise = Input(shape=(self.latent_dim,))
        img = model(noise)

        return Model(noise, img) 

def creat_discriminator(self):
        # layer 0
        image_A = Input(shape=self.image_shape)
        image_B = Input(shape=self.image_shape)
        combined_images = Concatenate(axis=-1)([image_A, image_B])
        # layer 1
        d1 = Conv2D(filters=64, kernel_size=4, strides=2, padding='same')(combined_images)
        d1 = LeakyReLU(alpha=0.2)(d1)
        # layer 2
        d2 = Conv2D(filters=128, kernel_size=4, strides=2, padding='same')(d1)
        d2 = LeakyReLU(alpha=0.2)(d2)
        d2 = BatchNormalization(momentum=0.8)(d2)
        # layer 3
        d3 = Conv2D(filters=128, kernel_size=4, strides=2, padding='same')(d2)
        d3 = LeakyReLU(alpha=0.2)(d3)
        d3 = BatchNormalization(momentum=0.8)(d3)
        # layer 4
        d4 = Conv2D(filters=128, kernel_size=4, strides=2, padding='same')(d3)
        d4 = LeakyReLU(alpha=0.2)(d4)
        d4 = BatchNormalization(momentum=0.8)(d4)
        validity = Conv2D(1, kernel_size=4, strides=1, padding='same')(d4)
        return Model([image_A, image_B], validity) 

def conv_block(input_tensor, filters, strides, d_rates):
    x = Conv2D(filters[0], kernel_size=1, dilation_rate=d_rates[0])(input_tensor)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[1], kernel_size=3, strides=strides, padding='same', dilation_rate=d_rates[1])(x)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[2], kernel_size=1, dilation_rate=d_rates[2])(x)
    x = BatchNormalization()(x)

    shortcut = Conv2D(filters[2], kernel_size=1, strides=strides)(input_tensor)
    shortcut = BatchNormalization()(shortcut)

    x = add([x, shortcut])
    x = Activation('relu')(x)

    return x 

def conv_block(input_tensor, filters, strides, d_rates):
    x = Conv2D(filters[0], kernel_size=1, dilation_rate=d_rates[0])(input_tensor)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[1], kernel_size=3, strides=strides, padding='same', dilation_rate=d_rates[1])(x)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[2], kernel_size=1, dilation_rate=d_rates[2])(x)
    x = BatchNormalization()(x)

    shortcut = Conv2D(filters[2], kernel_size=1, strides=strides)(input_tensor)
    shortcut = BatchNormalization()(shortcut)

    x = add([x, shortcut])
    x = Activation('relu')(x)

    return x 

def identity_block(input_tensor, filters, d_rates):
    x = Conv2D(filters[0], kernel_size=1, dilation_rate=d_rates[0])(input_tensor)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[1], kernel_size=3, padding='same', dilation_rate=d_rates[1])(x)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[2], kernel_size=1, dilation_rate=d_rates[2])(x)
    x = BatchNormalization()(x)

    x = add([x, input_tensor])
    x = Activation('relu')(x)

    return x 

def build_discriminator(self):

        model = Sequential()

        model.add(Conv2D(64, kernel_size=3, strides=2, input_shape=self.missing_shape, padding="same"))
        model.add(LeakyReLU(alpha=0.2))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Conv2D(128, kernel_size=3, strides=2, padding="same"))
        model.add(LeakyReLU(alpha=0.2))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Conv2D(256, kernel_size=3, padding="same"))
        model.add(LeakyReLU(alpha=0.2))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Flatten())
        model.add(Dense(1, activation='sigmoid'))
        model.summary()

        img = Input(shape=self.missing_shape)
        validity = model(img)

        return Model(img, validity) 

def conv_block(input_tensor, filters, strides, d_rates):
    x = Conv2D(filters[0], kernel_size=1, dilation_rate=d_rates[0])(input_tensor)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[1], kernel_size=3, strides=strides, padding='same', dilation_rate=d_rates[1])(x)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[2], kernel_size=1, dilation_rate=d_rates[2])(x)
    x = BatchNormalization()(x)

    shortcut = Conv2D(filters[2], kernel_size=1, strides=strides)(input_tensor)
    shortcut = BatchNormalization()(shortcut)

    x = add([x, shortcut])
    x = Activation('relu')(x)

    return x 

def __transition_up_block(ip, nb_filters, type='deconv', weight_decay=1E-4):
    ''' SubpixelConvolutional Upscaling (factor = 2)
    Args:
        ip: keras tensor
        nb_filters: number of layers
        type: can be 'upsampling', 'subpixel', 'deconv'. Determines type of upsampling performed
        weight_decay: weight decay factor
    Returns: keras tensor, after applying upsampling operation.
    '''

    if type == 'upsampling':
        x = UpSampling2D()(ip)
    elif type == 'subpixel':
        x = Conv2D(nb_filters, (3, 3), activation='relu', padding='same', kernel_regularizer=l2(weight_decay),
                   use_bias=False, kernel_initializer='he_normal')(ip)
        x = SubPixelUpscaling(scale_factor=2)(x)
        x = Conv2D(nb_filters, (3, 3), activation='relu', padding='same', kernel_regularizer=l2(weight_decay),
                   use_bias=False, kernel_initializer='he_normal')(x)
    else:
        x = Conv2DTranspose(nb_filters, (3, 3), activation='relu', padding='same', strides=(2, 2),
                            kernel_initializer='he_normal', kernel_regularizer=l2(weight_decay))(ip)

    return x 

def __transition_block(ip, nb_filter, compression=1.0, weight_decay=1e-4):
    ''' Apply BatchNorm, Relu 1x1, Conv2D, optional compression, dropout and Maxpooling2D
    Args:
        ip: keras tensor
        nb_filter: number of filters
        compression: calculated as 1 - reduction. Reduces the number of feature maps
                    in the transition block.
        dropout_rate: dropout rate
        weight_decay: weight decay factor
    Returns: keras tensor, after applying batch_norm, relu-conv, dropout, maxpool
    '''
    concat_axis = 1 if K.image_data_format() == 'channels_first' else -1

    x = BatchNormalization(axis=concat_axis, epsilon=1.1e-5)(ip)
    x = Activation('relu')(x)
    x = Conv2D(int(nb_filter * compression), (1, 1), kernel_initializer='he_normal', padding='same', use_bias=False,
               kernel_regularizer=l2(weight_decay))(x)
    x = AveragePooling2D((2, 2), strides=(2, 2))(x)

    return x 

def build_model(self):
        input = Input(shape=self.state_size)
        conv = Conv2D(16, (8, 8), strides=(4, 4), activation='relu')(input)
        conv = Conv2D(32, (4, 4), strides=(2, 2), activation='relu')(conv)
        conv = Flatten()(conv)
        fc = Dense(256, activation='relu')(conv)
        policy = Dense(self.action_size, activation='softmax')(fc)
        value = Dense(1, activation='linear')(fc)

        actor = Model(inputs=input, outputs=policy)
        critic = Model(inputs=input, outputs=value)

        actor.summary()
        critic.summary()

        return actor, critic 

def build_classifier(self):

        def clf_layer(layer_input, filters, f_size=4, normalization=True):
            """Classifier layer"""
            d = Conv2D(filters, kernel_size=f_size, strides=2, padding='same')(layer_input)
            d = LeakyReLU(alpha=0.2)(d)
            if normalization:
                d = InstanceNormalization()(d)
            return d

        img = Input(shape=self.img_shape)

        c1 = clf_layer(img, self.cf, normalization=False)
        c2 = clf_layer(c1, self.cf*2)
        c3 = clf_layer(c2, self.cf*4)
        c4 = clf_layer(c3, self.cf*8)
        c5 = clf_layer(c4, self.cf*8)

        class_pred = Dense(self.num_classes, activation='softmax')(Flatten()(c5))

        return Model(img, class_pred) 

def build_discriminator(self):

        img = Input(shape=self.img_shape)

        model = Sequential()
        model.add(Conv2D(64, kernel_size=4, strides=2, padding='same', input_shape=self.img_shape))
        model.add(LeakyReLU(alpha=0.8))
        model.add(Conv2D(128, kernel_size=4, strides=2, padding='same'))
        model.add(LeakyReLU(alpha=0.2))
        model.add(InstanceNormalization())
        model.add(Conv2D(256, kernel_size=4, strides=2, padding='same'))
        model.add(LeakyReLU(alpha=0.2))
        model.add(InstanceNormalization())

        model.summary()

        img = Input(shape=self.img_shape)
        features = model(img)

        validity = Conv2D(1, kernel_size=4, strides=1, padding='same')(features)

        label = Flatten()(features)
        label = Dense(self.num_classes+1, activation="softmax")(label)

        return Model(img, [validity, label]) 

def build_generator(self):

        model = Sequential()

        model.add(Dense(128 * 7 * 7, activation="relu", input_dim=self.latent_dim))
        model.add(Reshape((7, 7, 128)))
        model.add(BatchNormalization(momentum=0.8))
        model.add(UpSampling2D())
        model.add(Conv2D(128, kernel_size=3, padding="same"))
        model.add(Activation("relu"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(UpSampling2D())
        model.add(Conv2D(64, kernel_size=3, padding="same"))
        model.add(Activation("relu"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Conv2D(self.channels, kernel_size=3, padding='same'))
        model.add(Activation("tanh"))

        gen_input = Input(shape=(self.latent_dim,))
        img = model(gen_input)

        model.summary()

        return Model(gen_input, img) 

def discriminator(img_dim,alpha=0.2):
    model = Sequential()
    model.add(
            Conv2D(64, kernel_size=5,strides=2,
            padding='same',
            input_shape=img_dim)
            )
    model.add(LeakyReLU(alpha))
    model.add(Conv2D(128,kernel_size=5,strides=2,padding='same'))
    model.add(BatchNormalization())
    model.add(LeakyReLU(alpha))
    model.add(Conv2D(256,kernel_size=5,strides=2,padding='same'))
    model.add(BatchNormalization())
    model.add(LeakyReLU(alpha))
    model.add(Flatten())
    model.add(Dense(1))
    model.add(Activation('sigmoid'))
    return model

# Define a combination of Generator and Discriminator 

def identity_block(input_tensor, filters, d_rates):
    x = Conv2D(filters[0], kernel_size=1, dilation_rate=d_rates[0])(input_tensor)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[1], kernel_size=3, padding='same', dilation_rate=d_rates[1])(x)
    x = BatchNormalization()(x)
    x = Activation('relu')(x)

    x = Conv2D(filters[2], kernel_size=1, dilation_rate=d_rates[2])(x)
    x = BatchNormalization()(x)

    x = add([x, input_tensor])
    x = Activation('relu')(x)

    return x 

def build_generator(self):

        model = Sequential()

        model.add(Dense(128 * 7 * 7, activation="relu", input_dim=self.latent_dim))
        model.add(Reshape((7, 7, 128)))
        model.add(UpSampling2D())
        model.add(Conv2D(128, kernel_size=4, padding="same"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Activation("relu"))
        model.add(UpSampling2D())
        model.add(Conv2D(64, kernel_size=4, padding="same"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Activation("relu"))
        model.add(Conv2D(self.channels, kernel_size=4, padding="same"))
        model.add(Activation("tanh"))

        model.summary()

        noise = Input(shape=(self.latent_dim,))
        img = model(noise)

        return Model(noise, img) 

def build_discriminator(self):

        def d_layer(layer_input, filters, f_size=4, normalization=True):
            """Discriminator layer"""
            d = Conv2D(filters, kernel_size=f_size, strides=2, padding='same')(layer_input)
            d = LeakyReLU(alpha=0.2)(d)
            if normalization:
                d = InstanceNormalization()(d)
            return d

        img = Input(shape=self.img_shape)

        d1 = d_layer(img, self.df, normalization=False)
        d2 = d_layer(d1, self.df*2)
        d3 = d_layer(d2, self.df*4)
        d4 = d_layer(d3, self.df*8)

        validity = Conv2D(1, kernel_size=4, strides=1, padding='same')(d4)

        return Model(img, validity) 

def __transition_block(ip, nb_filter, compression=1.0, weight_decay=1e-4):
    ''' Apply BatchNorm, Relu 1x1, Conv2D, optional compression, dropout and Maxpooling2D
    Args:
        ip: keras tensor
        nb_filter: number of filters
        compression: calculated as 1 - reduction. Reduces the number of feature maps
                    in the transition block.
        dropout_rate: dropout rate
        weight_decay: weight decay factor
    Returns: keras tensor, after applying batch_norm, relu-conv, dropout, maxpool
    '''
    concat_axis = 1 if K.image_data_format() == 'channels_first' else -1

    x = BatchNormalization(axis=concat_axis, epsilon=1.1e-5)(ip)
    x = Activation('relu')(x)
    x = Conv2D(int(nb_filter * compression), (1, 1), kernel_initializer='he_normal', padding='same', use_bias=False,
               kernel_regularizer=l2(weight_decay))(x)
    x = AveragePooling2D((2, 2), strides=(2, 2))(x)

    # global context block
    x = global_context_block(x)

    return x 

def build_discriminator(self):

        def d_layer(layer_input, filters, f_size=4, bn=True):
            """Discriminator layer"""
            d = Conv2D(filters, kernel_size=f_size, strides=2, padding='same')(layer_input)
            d = LeakyReLU(alpha=0.2)(d)
            if bn:
                d = BatchNormalization(momentum=0.8)(d)
            return d

        img_A = Input(shape=self.img_shape)
        img_B = Input(shape=self.img_shape)

        # Concatenate image and conditioning image by channels to produce input
        combined_imgs = Concatenate(axis=-1)([img_A, img_B])

        d1 = d_layer(combined_imgs, self.df, bn=False)
        d2 = d_layer(d1, self.df*2)
        d3 = d_layer(d2, self.df*4)
        d4 = d_layer(d3, self.df*8)

        validity = Conv2D(1, kernel_size=4, strides=1, padding='same')(d4)

        return Model([img_A, img_B], validity) 

def build_generator(self):

        model = Sequential()

        model.add(Dense(128 * 7 * 7, activation="relu", input_dim=self.latent_dim))
        model.add(Reshape((7, 7, 128)))
        model.add(UpSampling2D())
        model.add(Conv2D(128, kernel_size=3, padding="same"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Activation("relu"))
        model.add(UpSampling2D())
        model.add(Conv2D(64, kernel_size=3, padding="same"))
        model.add(BatchNormalization(momentum=0.8))
        model.add(Activation("relu"))
        model.add(Conv2D(self.channels, kernel_size=3, padding="same"))
        model.add(Activation("tanh"))

        model.summary()

        noise = Input(shape=(self.latent_dim,))
        img = model(noise)

        return Model(noise, img) 

def get_unet_model(input_channel_num=3, out_ch=3, start_ch=64, depth=4, inc_rate=2., activation='relu',
         dropout=0.5, batchnorm=False, maxpool=True, upconv=True, residual=False):
    def _conv_block(m, dim, acti, bn, res, do=0):
        n = Conv2D(dim, 3, activation=acti, padding='same')(m)
        n = BatchNormalization()(n) if bn else n
        n = Dropout(do)(n) if do else n
        n = Conv2D(dim, 3, activation=acti, padding='same')(n)
        n = BatchNormalization()(n) if bn else n

        return Concatenate()([m, n]) if res else n

    def _level_block(m, dim, depth, inc, acti, do, bn, mp, up, res):
        if depth > 0:
            n = _conv_block(m, dim, acti, bn, res)
            m = MaxPooling2D()(n) if mp else Conv2D(dim, 3, strides=2, padding='same')(n)
            m = _level_block(m, int(inc * dim), depth - 1, inc, acti, do, bn, mp, up, res)
            if up:
                m = UpSampling2D()(m)
                m = Conv2D(dim, 2, activation=acti, padding='same')(m)
            else:
                m = Conv2DTranspose(dim, 3, strides=2, activation=acti, padding='same')(m)
            n = Concatenate()([n, m])
            m = _conv_block(n, dim, acti, bn, res)
        else:
            m = _conv_block(m, dim, acti, bn, res, do)

        return m

    i = Input(shape=(None, None, input_channel_num))
    o = _level_block(i, start_ch, depth, inc_rate, activation, dropout, batchnorm, maxpool, upconv, residual)
    o = Conv2D(out_ch, 1)(o)
    model = Model(inputs=i, outputs=o)

    return model 

def build_model(self):
        input = Input(shape=self.state_size)
        conv = Conv2D(16, (8, 8), strides=(4, 4), activation='relu')(input)
        conv = Conv2D(32, (4, 4), strides=(2, 2), activation='relu')(conv)
        conv = Flatten()(conv)
        fc = Dense(256, activation='relu')(conv)
        policy = Dense(self.action_size, activation='softmax')(fc)
        value = Dense(1, activation='linear')(fc)

        actor = Model(inputs=input, outputs=policy)
        critic = Model(inputs=input, outputs=value)

        actor.summary()
        critic.summary()

        return actor, critic 

def build_model(self):
        input = Input(shape=self.state_size)
        conv = Conv2D(16, (8, 8), strides=(4, 4), activation='relu')(input)
        conv = Conv2D(32, (4, 4), strides=(2, 2), activation='relu')(conv)
        conv = Flatten()(conv)
        fc = Dense(256, activation='relu')(conv)

        policy = Dense(self.action_size, activation='softmax')(fc)
        value = Dense(1, activation='linear')(fc)

        actor = Model(inputs=input, outputs=policy)
        critic = Model(inputs=input, outputs=value)

        # 가치와 정책을 예측하는 함수를 만들어냄
        actor._make_predict_function()
        critic._make_predict_function()

        actor.summary()
        critic.summary()

        return actor, critic

    # 정책신경망을 업데이트하는 함수 

def build_local_model(self):
        input = Input(shape=self.state_size)
        conv = Conv2D(16, (8, 8), strides=(4, 4), activation='relu')(input)
        conv = Conv2D(32, (4, 4), strides=(2, 2), activation='relu')(conv)
        conv = Flatten()(conv)
        fc = Dense(256, activation='relu')(conv)
        policy = Dense(self.action_size, activation='softmax')(fc)
        value = Dense(1, activation='linear')(fc)

        local_actor = Model(inputs=input, outputs=policy)
        local_critic = Model(inputs=input, outputs=value)

        local_actor._make_predict_function()
        local_critic._make_predict_function()

        local_actor.set_weights(self.actor.get_weights())
        local_critic.set_weights(self.critic.get_weights())

        local_actor.summary()
        local_critic.summary()

        return local_actor, local_critic

    # 로컬신경망을 글로벌신경망으로 업데이트 

def model_create(input_shape, num_classes):
        logging.debug('input_shape {}'.format(input_shape))

        model = Sequential()

        model.add(Conv2D(32, (3, 3), border_mode='same', input_shape=input_shape))
        model.add(Activation('relu'))

        model.add(Conv2D(32, (3, 3)))
        model.add(Activation('relu'))
        model.add(MaxPooling2D(pool_size=(2, 2)))
        model.add(Dropout(0.5))

        model.add(Flatten())
        model.add(Dense(128))
        model.add(Activation('relu'))
        model.add(Dropout(0.5))

        model.add(Dense(num_classes))
        model.add(Activation('softmax'))

        # use binary_crossentropy if has just 2 prediction yes or no
        model.compile(loss='categorical_crossentropy', optimizer='adadelta', metrics=['accuracy'])

        return model 

def Decoder(name):
    input_ = Input( shape=(8,8,512) )
    skip_in = Input( shape=(8,8,512) )

    x = input_
    x = upscale(512)(x)
    x = res_block(x, 512)
    x = upscale(256)(x)
    x = res_block(x, 256)
    x = upscale(128)(x)
    x = res_block(x, 128)
    x = upscale(64)(x)
    x = Conv2D( 3, kernel_size=5, padding='same', activation='sigmoid' )(x)

    y = input_
    y = upscale(512)(y)
    y = upscale(256)(y)
    y = upscale(128)(y)
    y = upscale(64)(y)
    y = Conv2D( 1, kernel_size=5, padding='same', activation='sigmoid' )(y)

    return Model( [input_], outputs=[x,y] ) 

def build_localmodel(self):
        input = Input(shape=self.state_size)
        conv = Conv2D(16, (8, 8), strides=(4, 4), activation='relu')(input)
        conv = Conv2D(32, (4, 4), strides=(2, 2), activation='relu')(conv)
        conv = Flatten()(conv)
        fc = Dense(256, activation='relu')(conv)
        policy = Dense(self.action_size, activation='softmax')(fc)
        value = Dense(1, activation='linear')(fc)

        actor = Model(inputs=input, outputs=policy)
        critic = Model(inputs=input, outputs=value)

        actor._make_predict_function()
        critic._make_predict_function()

        actor.set_weights(self.actor.get_weights())
        critic.set_weights(self.critic.get_weights())

        actor.summary()
        critic.summary()

        return actor, critic 

def build_model(self):
        input = Input(shape=self.state_size)
        conv = Conv2D(16, (8, 8), strides=(4, 4), activation='relu')(input)
        conv = Conv2D(32, (4, 4), strides=(2, 2), activation='relu')(conv)
        conv = Flatten()(conv)
        fc = Dense(256, activation='relu')(conv)
        policy = Dense(self.action_size, activation='softmax')(fc)
        value = Dense(1, activation='linear')(fc)

        actor = Model(inputs=input, outputs=policy)
        critic = Model(inputs=input, outputs=value)

        actor._make_predict_function()
        critic._make_predict_function()

        actor.summary()
        critic.summary()

        return actor, critic

    # make loss function for Policy Gradient
    # [log(action probability) * advantages] will be input for the back prop
    # we add entropy of action probability to loss 

def __transition_block(ip, nb_filter, compression=1.0, weight_decay=1e-4):
    ''' Apply BatchNorm, Relu 1x1, Conv2D, optional compression, dropout and Maxpooling2D
    Args:
        ip: keras tensor
        nb_filter: number of filters
        compression: calculated as 1 - reduction. Reduces the number of feature maps
                    in the transition block.
        dropout_rate: dropout rate
        weight_decay: weight decay factor
    Returns: keras tensor, after applying batch_norm, relu-conv, dropout, maxpool
    '''
    concat_axis = 1 if K.image_data_format() == 'channels_first' else -1

    x = BatchNormalization(axis=concat_axis, epsilon=1.1e-5)(ip)
    x = Activation('relu')(x)
    x = Conv2D(int(nb_filter * compression), (1, 1), kernel_initializer='he_normal', padding='same', use_bias=False,
               kernel_regularizer=l2(weight_decay))(x)
    x = AveragePooling2D((2, 2), strides=(2, 2))(x)

    return x 

def __conv_block(ip, nb_filter, bottleneck=False, dropout_rate=None, weight_decay=1e-4):
    ''' Apply BatchNorm, Relu, 3x3 Conv2D, optional bottleneck block and dropout
    Args:
        ip: Input keras tensor
        nb_filter: number of filters
        bottleneck: add bottleneck block
        dropout_rate: dropout rate
        weight_decay: weight decay factor
    Returns: keras tensor with batch_norm, relu and convolution2d added (optional bottleneck)
    '''
    concat_axis = 1 if K.image_data_format() == 'channels_first' else -1

    x = BatchNormalization(axis=concat_axis, epsilon=1.1e-5)(ip)
    x = Activation('relu')(x)

    if bottleneck:
        inter_channel = nb_filter * 4  # Obtained from https://github.com/liuzhuang13/DenseNet/blob/master/densenet.lua

        x = Conv2D(inter_channel, (1, 1), kernel_initializer='he_normal', padding='same', use_bias=False,
                   kernel_regularizer=l2(weight_decay))(x)
        x = BatchNormalization(axis=concat_axis, epsilon=1.1e-5)(x)
        x = Activation('relu')(x)

    x = Conv2D(nb_filter, (3, 3), kernel_initializer='he_normal', padding='same', use_bias=False)(x)
    if dropout_rate:
        x = Dropout(dropout_rate)(x)

    return x