Spectral_Normalization.py

from keras import backend as K
from keras.engine import *
from keras.legacy import interfaces
from keras import activations
from keras import initializers
from keras import regularizers
from keras import constraints
from keras.utils.generic_utils import func_dump
from keras.utils.generic_utils import func_load
from keras.utils.generic_utils import deserialize_keras_object
from keras.utils.generic_utils import has_arg
from keras.utils import conv_utils
from keras.legacy import interfaces
from keras.layers import Dense, Conv1D, Conv2D, Conv3D, Conv2DTranspose, Embedding
import tensorflow as tf
from keras.engine.network import Layer
from keras.layers import InputSpec
import keras.backend as K

class DenseSN(Dense):
    def build(self, input_shape):
        assert len(input_shape) >= 2
        input_dim = input_shape[-1]
        self.kernel = self.add_weight(shape=(input_dim, self.units),
                                      initializer=self.kernel_initializer,
                                      name='kernel',
                                      regularizer=self.kernel_regularizer,
                                      constraint=self.kernel_constraint)
        if self.use_bias:
            self.bias = self.add_weight(shape=(self.units,),
                                        initializer=self.bias_initializer,
                                        name='bias',
                                        regularizer=self.bias_regularizer,
                                        constraint=self.bias_constraint)
        else:
            self.bias = None
        self.u = self.add_weight(shape=tuple([1, self.kernel.shape.as_list()[-1]]),
                                 initializer=initializers.RandomNormal(0, 1),
                                 name='sn',
                                 trainable=False)
        self.input_spec = InputSpec(min_ndim=2, axes={-1: input_dim})
        self.built = True
        
    def call(self, inputs, training=None):
        def _l2normalize(v, eps=1e-12):
            return v / (K.sum(v ** 2) ** 0.5 + eps)
        def power_iteration(W, u):
            _u = u
            _v = _l2normalize(K.dot(_u, K.transpose(W)))
            _u = _l2normalize(K.dot(_v, W))
            return _u, _v
        W_shape = self.kernel.shape.as_list()
        #Flatten the Tensor
        W_reshaped = K.reshape(self.kernel, [-1, W_shape[-1]])
        _u, _v = power_iteration(W_reshaped, self.u)
        #Calculate Sigma
        sigma=K.dot(_v, W_reshaped)
        sigma=K.dot(sigma, K.transpose(_u))
        #normalize it
        W_bar = W_reshaped / sigma
        #reshape weight tensor
        if training in {0, False}:
            W_bar = K.reshape(W_bar, W_shape)
        else:
            with tf.control_dependencies([self.u.assign(_u)]):
                 W_bar = K.reshape(W_bar, W_shape)  
        output = K.dot(inputs, W_bar)
        if self.use_bias:
            output = K.bias_add(output, self.bias, data_format='channels_last')
        if self.activation is not None:
            output = self.activation(output)
        return output 
        
class _ConvSN(Layer):

    def __init__(self, rank,
                 filters,
                 kernel_size,
                 strides=1,
                 padding='valid',
                 data_format=None,
                 dilation_rate=1,
                 activation=None,
                 use_bias=True,
                 kernel_initializer='glorot_uniform',
                 bias_initializer='zeros',
                 kernel_regularizer=None,
                 bias_regularizer=None,
                 activity_regularizer=None,
                 kernel_constraint=None,
                 bias_constraint=None,
                 spectral_normalization=True,
                 **kwargs):
        super(_ConvSN, self).__init__(**kwargs)
        self.rank = rank
        self.filters = filters
        self.kernel_size = conv_utils.normalize_tuple(kernel_size, rank, 'kernel_size')
        self.strides = conv_utils.normalize_tuple(strides, rank, 'strides')
        self.padding = conv_utils.normalize_padding(padding)
        self.data_format = conv_utils.normalize_data_format(data_format)
        self.dilation_rate = conv_utils.normalize_tuple(dilation_rate, rank, 'dilation_rate')
        self.activation = activations.get(activation)
        self.use_bias = use_bias
        self.kernel_initializer = initializers.get(kernel_initializer)
        self.bias_initializer = initializers.get(bias_initializer)
        self.kernel_regularizer = regularizers.get(kernel_regularizer)
        self.bias_regularizer = regularizers.get(bias_regularizer)
        self.activity_regularizer = regularizers.get(activity_regularizer)
        self.kernel_constraint = constraints.get(kernel_constraint)
        self.bias_constraint = constraints.get(bias_constraint)
        self.input_spec = InputSpec(ndim=self.rank + 2)
        self.spectral_normalization = spectral_normalization
        self.u = None
        
    def _l2normalize(self, v, eps=1e-12):
        return v / (K.sum(v ** 2) ** 0.5 + eps)
    
    def power_iteration(self, u, W):
        '''
        Accroding the paper, we only need to do power iteration one time.
        '''
        v = self._l2normalize(K.dot(u, K.transpose(W)))
        u = self._l2normalize(K.dot(v, W))
        return u, v
    def build(self, input_shape):
        if self.data_format == 'channels_first':
            channel_axis = 1
        else:
            channel_axis = -1
        if input_shape[channel_axis] is None:
            raise ValueError('The channel dimension of the inputs '
                             'should be defined. Found `None`.')
        input_dim = input_shape[channel_axis]
        kernel_shape = self.kernel_size + (input_dim, self.filters)

        self.kernel = self.add_weight(shape=kernel_shape,
                                      initializer=self.kernel_initializer,
                                      name='kernel',
                                      regularizer=self.kernel_regularizer,
                                      constraint=self.kernel_constraint)

        #Spectral Normalization
        if self.spectral_normalization:
            self.u = self.add_weight(shape=tuple([1, self.kernel.shape.as_list()[-1]]),
                                     initializer=initializers.RandomNormal(0, 1),
                                     name='sn',
                                     trainable=False)
        
        if self.use_bias:
            self.bias = self.add_weight(shape=(self.filters,),
                                        initializer=self.bias_initializer,
                                        name='bias',
                                        regularizer=self.bias_regularizer,
                                        constraint=self.bias_constraint)
        else:
            self.bias = None
        # Set input spec.
        self.input_spec = InputSpec(ndim=self.rank + 2,
                                    axes={channel_axis: input_dim})
        self.built = True

    def call(self, inputs):
        def _l2normalize(v, eps=1e-12):
            return v / (K.sum(v ** 2) ** 0.5 + eps)
        def power_iteration(W, u):
            _u = u
            _v = _l2normalize(K.dot(_u, K.transpose(W)))
            _u = _l2normalize(K.dot(_v, W))
            return _u, _v
        
        if self.spectral_normalization:
            W_shape = self.kernel.shape.as_list()
            #Flatten the Tensor
            W_reshaped = K.reshape(self.kernel, [-1, W_shape[-1]])
            _u, _v = power_iteration(W_reshaped, self.u)
            #Calculate Sigma
            sigma=K.dot(_v, W_reshaped)
            sigma=K.dot(sigma, K.transpose(_u))
            #normalize it
            W_bar = W_reshaped / sigma
            #reshape weight tensor
            if training in {0, False}:
                W_bar = K.reshape(W_bar, W_shape)
            else:
                with tf.control_dependencies([self.u.assign(_u)]):
                    W_bar = K.reshape(W_bar, W_shape)

            #update weitht
            self.kernel = W_bar
        
        if self.rank == 1:
            outputs = K.conv1d(
                inputs,
                self.kernel,
                strides=self.strides[0],
                padding=self.padding,
                data_format=self.data_format,
                dilation_rate=self.dilation_rate[0])
        if self.rank == 2:
            outputs = K.conv2d(
                inputs,
                self.kernel,
                strides=self.strides,
                padding=self.padding,
                data_format=self.data_format,
                dilation_rate=self.dilation_rate)
        if self.rank == 3:
            outputs = K.conv3d(
                inputs,
                self.kernel,
                strides=self.strides,
                padding=self.padding,
                data_format=self.data_format,
                dilation_rate=self.dilation_rate)

        if self.use_bias:
            outputs = K.bias_add(
                outputs,
                self.bias,
                data_format=self.data_format)

        if self.activation is not None:
            return self.activation(outputs)
        return outputs

    def compute_output_shape(self, input_shape):
        if self.data_format == 'channels_last':
            space = input_shape[1:-1]
            new_space = []
            for i in range(len(space)):
                new_dim = conv_utils.conv_output_length(
                    space[i],
                    self.kernel_size[i],
                    padding=self.padding,
                    stride=self.strides[i],
                    dilation=self.dilation_rate[i])
                new_space.append(new_dim)
            return (input_shape[0],) + tuple(new_space) + (self.filters,)
        if self.data_format == 'channels_first':
            space = input_shape[2:]
            new_space = []
            for i in range(len(space)):
                new_dim = conv_utils.conv_output_length(
                    space[i],
                    self.kernel_size[i],
                    padding=self.padding,
                    stride=self.strides[i],
                    dilation=self.dilation_rate[i])
                new_space.append(new_dim)
            return (input_shape[0], self.filters) + tuple(new_space)

    def get_config(self):
        config = {
            'rank': self.rank,
            'filters': self.filters,
            'kernel_size': self.kernel_size,
            'strides': self.strides,
            'padding': self.padding,
            'data_format': self.data_format,
            'dilation_rate': self.dilation_rate,
            'activation': activations.serialize(self.activation),
            'use_bias': self.use_bias,
            'kernel_initializer': initializers.serialize(self.kernel_initializer),
            'bias_initializer': initializers.serialize(self.bias_initializer),
            'kernel_regularizer': regularizers.serialize(self.kernel_regularizer),
            'bias_regularizer': regularizers.serialize(self.bias_regularizer),
            'activity_regularizer': regularizers.serialize(self.activity_regularizer),
            'kernel_constraint': constraints.serialize(self.kernel_constraint),
            'bias_constraint': constraints.serialize(self.bias_constraint)
        }
        base_config = super(_Conv, self).get_config()
        return dict(list(base_config.items()) + list(config.items()))
    
class ConvSN2D(Conv2D):

    def build(self, input_shape):
        if self.data_format == 'channels_first':
            channel_axis = 1
        else:
            channel_axis = -1
        if input_shape[channel_axis] is None:
            raise ValueError('The channel dimension of the inputs '
                             'should be defined. Found `None`.')
        input_dim = input_shape[channel_axis]
        kernel_shape = self.kernel_size + (input_dim, self.filters)

        self.kernel = self.add_weight(shape=kernel_shape,
                                      initializer=self.kernel_initializer,
                                      name='kernel',
                                      regularizer=self.kernel_regularizer,
                                      constraint=self.kernel_constraint)

        if self.use_bias:
            self.bias = self.add_weight(shape=(self.filters,),
                                        initializer=self.bias_initializer,
                                        name='bias',
                                        regularizer=self.bias_regularizer,
                                        constraint=self.bias_constraint)
        else:
            self.bias = None
            
        self.u = self.add_weight(shape=tuple([1, self.kernel.shape.as_list()[-1]]),
                         initializer=initializers.RandomNormal(0, 1),
                         name='sn',
                         trainable=False)
        
        # Set input spec.
        self.input_spec = InputSpec(ndim=self.rank + 2,
                                    axes={channel_axis: input_dim})
        self.built = True
    def call(self, inputs, training=None):
        def _l2normalize(v, eps=1e-12):
            return v / (K.sum(v ** 2) ** 0.5 + eps)
        def power_iteration(W, u):
            #Accroding the paper, we only need to do power iteration one time.
            _u = u
            _v = _l2normalize(K.dot(_u, K.transpose(W)))
            _u = _l2normalize(K.dot(_v, W))
            return _u, _v
        #Spectral Normalization
        W_shape = self.kernel.shape.as_list()
        #Flatten the Tensor
        W_reshaped = K.reshape(self.kernel, [-1, W_shape[-1]])
        _u, _v = power_iteration(W_reshaped, self.u)
        #Calculate Sigma
        sigma=K.dot(_v, W_reshaped)
        sigma=K.dot(sigma, K.transpose(_u))
        #normalize it
        W_bar = W_reshaped / sigma
        #reshape weight tensor
        if training in {0, False}:
            W_bar = K.reshape(W_bar, W_shape)
        else:
            with tf.control_dependencies([self.u.assign(_u)]):
                W_bar = K.reshape(W_bar, W_shape)
                
        outputs = K.conv2d(
                inputs,
                W_bar,
                strides=self.strides,
                padding=self.padding,
                data_format=self.data_format,
                dilation_rate=self.dilation_rate)
        if self.use_bias:
            outputs = K.bias_add(
                outputs,
                self.bias,
                data_format=self.data_format)
        if self.activation is not None:
            return self.activation(outputs)
        return outputs
    
class ConvSN1D(Conv1D):
    
    def build(self, input_shape):
        if self.data_format == 'channels_first':
            channel_axis = 1
        else:
            channel_axis = -1
        if input_shape[channel_axis] is None:
            raise ValueError('The channel dimension of the inputs '
                             'should be defined. Found `None`.')
        input_dim = input_shape[channel_axis]
        kernel_shape = self.kernel_size + (input_dim, self.filters)

        self.kernel = self.add_weight(shape=kernel_shape,
                                      initializer=self.kernel_initializer,
                                      name='kernel',
                                      regularizer=self.kernel_regularizer,
                                      constraint=self.kernel_constraint)

        if self.use_bias:
            self.bias = self.add_weight(shape=(self.filters,),
                                        initializer=self.bias_initializer,
                                        name='bias',
                                        regularizer=self.bias_regularizer,
                                        constraint=self.bias_constraint)
        else:
            self.bias = None
            
        self.u = self.add_weight(shape=tuple([1, self.kernel.shape.as_list()[-1]]),
                 initializer=initializers.RandomNormal(0, 1),
                 name='sn',
                 trainable=False)
        # Set input spec.
        self.input_spec = InputSpec(ndim=self.rank + 2,
                                    axes={channel_axis: input_dim})
        self.built = True
        
    def call(self, inputs, training=None):
        def _l2normalize(v, eps=1e-12):
            return v / (K.sum(v ** 2) ** 0.5 + eps)
        def power_iteration(W, u):
            #Accroding the paper, we only need to do power iteration one time.
            _u = u
            _v = _l2normalize(K.dot(_u, K.transpose(W)))
            _u = _l2normalize(K.dot(_v, W))
            return _u, _v
        #Spectral Normalization
        W_shape = self.kernel.shape.as_list()
        #Flatten the Tensor
        W_reshaped = K.reshape(self.kernel, [-1, W_shape[-1]])
        _u, _v = power_iteration(W_reshaped, self.u)
        #Calculate Sigma
        sigma=K.dot(_v, W_reshaped)
        sigma=K.dot(sigma, K.transpose(_u))
        #normalize it
        W_bar = W_reshaped / sigma
        #reshape weight tensor
        if training in {0, False}:
            W_bar = K.reshape(W_bar, W_shape)
        else:
            with tf.control_dependencies([self.u.assign(_u)]):
                W_bar = K.reshape(W_bar, W_shape)
                
        outputs = K.conv1d(
                inputs,
                W_bar,
                strides=self.strides,
                padding=self.padding,
                data_format=self.data_format,
                dilation_rate=self.dilation_rate)
        if self.use_bias:
            outputs = K.bias_add(
                outputs,
                self.bias,
                data_format=self.data_format)
        if self.activation is not None:
            return self.activation(outputs)
        return outputs

class ConvSN3D(Conv3D):    
    def build(self, input_shape):
        if self.data_format == 'channels_first':
            channel_axis = 1
        else:
            channel_axis = -1
        if input_shape[channel_axis] is None:
            raise ValueError('The channel dimension of the inputs '
                             'should be defined. Found `None`.')
        input_dim = input_shape[channel_axis]
        kernel_shape = self.kernel_size + (input_dim, self.filters)

        self.kernel = self.add_weight(shape=kernel_shape,
                                      initializer=self.kernel_initializer,
                                      name='kernel',
                                      regularizer=self.kernel_regularizer,
                                      constraint=self.kernel_constraint)
        
        self.u = self.add_weight(shape=tuple([1, self.kernel.shape.as_list()[-1]]),
                         initializer=initializers.RandomNormal(0, 1),
                         name='sn',
                         trainable=False)
        
        if self.use_bias:
            self.bias = self.add_weight(shape=(self.filters,),
                                        initializer=self.bias_initializer,
                                        name='bias',
                                        regularizer=self.bias_regularizer,
                                        constraint=self.bias_constraint)
        else:
            self.bias = None
        # Set input spec.
        self.input_spec = InputSpec(ndim=self.rank + 2,
                                    axes={channel_axis: input_dim})
        self.built = True

    def call(self, inputs, training=None):
        def _l2normalize(v, eps=1e-12):
            return v / (K.sum(v ** 2) ** 0.5 + eps)
        def power_iteration(W, u):
            #Accroding the paper, we only need to do power iteration one time.
            _u = u
            _v = _l2normalize(K.dot(_u, K.transpose(W)))
            _u = _l2normalize(K.dot(_v, W))
            return _u, _v
        #Spectral Normalization
        W_shape = self.kernel.shape.as_list()
        #Flatten the Tensor
        W_reshaped = K.reshape(self.kernel, [-1, W_shape[-1]])
        _u, _v = power_iteration(W_reshaped, self.u)
        #Calculate Sigma
        sigma=K.dot(_v, W_reshaped)
        sigma=K.dot(sigma, K.transpose(_u))
        #normalize it
        W_bar = W_reshaped / sigma
        #reshape weight tensor
        if training in {0, False}:
            W_bar = K.reshape(W_bar, W_shape)
        else:
            with tf.control_dependencies([self.u.assign(_u)]):
                W_bar = K.reshape(W_bar, W_shape)
                
        outputs = K.conv3d(
                inputs,
                W_bar,
                strides=self.strides,
                padding=self.padding,
                data_format=self.data_format,
                dilation_rate=self.dilation_rate)
        if self.use_bias:
            outputs = K.bias_add(
                outputs,
                self.bias,
                data_format=self.data_format)
        if self.activation is not None:
            return self.activation(outputs)
        return outputs

        
class EmbeddingSN(Embedding):
    
    def build(self, input_shape):
        self.embeddings = self.add_weight(
            shape=(self.input_dim, self.output_dim),
            initializer=self.embeddings_initializer,
            name='embeddings',
            regularizer=self.embeddings_regularizer,
            constraint=self.embeddings_constraint,
            dtype=self.dtype)
        
        self.u = self.add_weight(shape=tuple([1, self.embeddings.shape.as_list()[-1]]),
                         initializer=initializers.RandomNormal(0, 1),
                         name='sn',
                         trainable=False)
        
        self.built = True
        
    def call(self, inputs):
        if K.dtype(inputs) != 'int32':
            inputs = K.cast(inputs, 'int32')
            
        def _l2normalize(v, eps=1e-12):
            return v / (K.sum(v ** 2) ** 0.5 + eps)
        def power_iteration(W, u):
            #Accroding the paper, we only need to do power iteration one time.
            _u = u
            _v = _l2normalize(K.dot(_u, K.transpose(W)))
            _u = _l2normalize(K.dot(_v, W))
            return _u, _v
        W_shape = self.embeddings.shape.as_list()
        #Flatten the Tensor
        W_reshaped = K.reshape(self.embeddings, [-1, W_shape[-1]])
        _u, _v = power_iteration(W_reshaped, self.u)
        #Calculate Sigma
        sigma=K.dot(_v, W_reshaped)
        sigma=K.dot(sigma, K.transpose(_u))
        #normalize it
        W_bar = W_reshaped / sigma
        #reshape weight tensor
        if training in {0, False}:
            W_bar = K.reshape(W_bar, W_shape)
        else:
            with tf.control_dependencies([self.u.assign(_u)]):
                W_bar = K.reshape(W_bar, W_shape)
        self.embeddings = W_bar
            
        out = K.gather(self.embeddings, inputs)
        return out 

class ConvSN2DTranspose(Conv2DTranspose):

    def build(self, input_shape):
        if len(input_shape) != 4:
            raise ValueError('Inputs should have rank ' +
                             str(4) +
                             '; Received input shape:', str(input_shape))
        if self.data_format == 'channels_first':
            channel_axis = 1
        else:
            channel_axis = -1
        if input_shape[channel_axis] is None:
            raise ValueError('The channel dimension of the inputs '
                             'should be defined. Found `None`.')
        input_dim = input_shape[channel_axis]
        kernel_shape = self.kernel_size + (self.filters, input_dim)

        self.kernel = self.add_weight(shape=kernel_shape,
                                      initializer=self.kernel_initializer,
                                      name='kernel',
                                      regularizer=self.kernel_regularizer,
                                      constraint=self.kernel_constraint)
        if self.use_bias:
            self.bias = self.add_weight(shape=(self.filters,),
                                        initializer=self.bias_initializer,
                                        name='bias',
                                        regularizer=self.bias_regularizer,
                                        constraint=self.bias_constraint)
        else:
            self.bias = None
            
        self.u = self.add_weight(shape=tuple([1, self.kernel.shape.as_list()[-1]]),
                         initializer=initializers.RandomNormal(0, 1),
                         name='sn',
                         trainable=False)
        
        # Set input spec.
        self.input_spec = InputSpec(ndim=4, axes={channel_axis: input_dim})
        self.built = True  
    
    def call(self, inputs):
        input_shape = K.shape(inputs)
        batch_size = input_shape[0]
        if self.data_format == 'channels_first':
            h_axis, w_axis = 2, 3
        else:
            h_axis, w_axis = 1, 2

        height, width = input_shape[h_axis], input_shape[w_axis]
        kernel_h, kernel_w = self.kernel_size
        stride_h, stride_w = self.strides
        if self.output_padding is None:
            out_pad_h = out_pad_w = None
        else:
            out_pad_h, out_pad_w = self.output_padding

        # Infer the dynamic output shape:
        out_height = conv_utils.deconv_length(height,
                                              stride_h, kernel_h,
                                              self.padding,
                                              out_pad_h)
        out_width = conv_utils.deconv_length(width,
                                             stride_w, kernel_w,
                                             self.padding,
                                             out_pad_w)
        if self.data_format == 'channels_first':
            output_shape = (batch_size, self.filters, out_height, out_width)
        else:
            output_shape = (batch_size, out_height, out_width, self.filters)
            
        #Spectral Normalization    
        def _l2normalize(v, eps=1e-12):
            return v / (K.sum(v ** 2) ** 0.5 + eps)
        def power_iteration(W, u):
            #Accroding the paper, we only need to do power iteration one time.
            _u = u
            _v = _l2normalize(K.dot(_u, K.transpose(W)))
            _u = _l2normalize(K.dot(_v, W))
            return _u, _v
        W_shape = self.kernel.shape.as_list()
        #Flatten the Tensor
        W_reshaped = K.reshape(self.kernel, [-1, W_shape[-1]])
        _u, _v = power_iteration(W_reshaped, self.u)
        #Calculate Sigma
        sigma=K.dot(_v, W_reshaped)
        sigma=K.dot(sigma, K.transpose(_u))
        #normalize it
        W_bar = W_reshaped / sigma
        #reshape weight tensor
        if training in {0, False}:
            W_bar = K.reshape(W_bar, W_shape)
        else:
            with tf.control_dependencies([self.u.assign(_u)]):
                W_bar = K.reshape(W_bar, W_shape)
        self.kernel = W_bar
        
        outputs = K.conv2d_transpose(
            inputs,
            self.kernel,
            output_shape,
            self.strides,
            padding=self.padding,
            data_format=self.data_format)

        if self.use_bias:
            outputs = K.bias_add(
                outputs,
                self.bias,
                data_format=self.data_format)

        if self.activation is not None:
            return self.activation(outputs)
        return outputs


class SelfAttention(Layer):
    
    def __init__(self, ch, **kwargs):
        super(SelfAttention, self).__init__(**kwargs)
        self.channels = ch
        self.filters_f_g = self.channels // 8
        self.filters_h = self.channels
    
    def build(self, input_shape):
        kernel_shape_f_g = (1, 1) + (self.channels, self.filters_f_g)
        kernel_shape_h   = (1, 1) + (self.channels, self.filters_h)
        
        self.gamma = self.add_weight(name='gamma', shape=[1], initializer='zeros', trainable=True)
        self.kernel_f = self.add_weight(shape=kernel_shape_f_g, initializer='glorot_uniform',name='kernel_f', trainable=True)
        self.kernel_g = self.add_weight(shape=kernel_shape_f_g,initializer='glorot_uniform',name='kernel_g',trainable=True)
        self.kernel_h = self.add_weight(shape=kernel_shape_h,initializer='glorot_uniform',name='kernel_h',trainable=True)
        super(SelfAttention, self).build(input_shape)
        self.input_spec = InputSpec(ndim=4,axes={3: input_shape[-1]})
        self.built = True

    def call(self, x):
        def hw_flatten(x):
            return K.reshape(x, shape=[K.shape(x)[0], K.shape(x)[1]*K.shape(x)[2], K.shape(x)[3]])
            
        f = K.conv2d(x,kernel=self.kernel_f,strides=(1, 1), padding='same')
        g = K.conv2d(x,kernel=self.kernel_g,strides=(1, 1), padding='same')
        h = K.conv2d(x,kernel=self.kernel_h,strides=(1, 1), padding='same')
         
        s = K.batch_dot(hw_flatten(g), K.permute_dimensions(hw_flatten(f), (0, 2, 1)))
         
        beta = K.softmax(s, axis=-1)  # ATTENTION MAP - Need to visualize for bonus mark
         
        o = K.batch_dot(beta, hw_flatten(h))
         
        o = K.reshape(o, shape=K.shape(x))
        x = self.gamma * o + x
                         
        return x
    
    def compute_output_shape(self, input_shape):
        return input_shape