def extract_image_patches(x, ksizes, ssizes, padding='same', data_format='tf'):
'''
Extract the patches from an image
# Parameters
x : The input image
ksizes : 2-d tuple with the kernel size
ssizes : 2-d tuple with the strides size
padding : 'same' or 'valid'
data_format : 'channels_last' or 'channels_first'
# Returns
The (k_w,k_h) patches extracted
TF ==> (batch_size,w,h,k_w,k_h,c)
TH ==> (batch_size,w,h,c,k_w,k_h)
'''
kernel = [1, ksizes[0], ksizes[1], 1]
strides = [1, ssizes[0], ssizes[1], 1]
padding = _preprocess_padding(padding)
if data_format == 'channels_first':
x = KTF.permute_dimensions(x, (0, 2, 3, 1))
bs_i, w_i, h_i, ch_i = KTF.int_shape(x)
patches = tf.extract_image_patches(x, kernel, strides, [1, 1, 1, 1],
padding)
# Reshaping to fit Theano
bs, w, h, ch = KTF.int_shape(patches)
patches = tf.reshape(
tf.transpose(
tf.reshape(patches,
[-1, w, h, tf.floordiv(ch, ch_i), ch_i]),
[0, 1, 2, 4, 3]), [-1, w, h, ch_i, ksizes[0], ksizes[1]])
if data_format == 'channels_last':
patches = KTF.permute_dimensions(patches, [0, 1, 2, 4, 5, 3])
return patches
def resize_images_bilinear(X,
height_factor=1,
width_factor=1,
target_height=None,
target_width=None,
data_format='default'):
'''Resizes the images contained in a 4D tensor of shape
- [batch, channels, height, width] (for 'channels_first' data_format)
- [batch, height, width, channels] (for 'channels_last' data_format)
by a factor of (height_factor, width_factor). Both factors should be
positive integers.
'''
if data_format == 'default':
data_format = K.image_data_format()
if data_format == 'channels_first':
original_shape = K.int_shape(X)
if target_height and target_width:
new_shape = tf.constant(
np.array((target_height, target_width)).astype('int32'))
else:
new_shape = tf.shape(X)[2:]
new_shape *= tf.constant(
np.array([height_factor, width_factor]).astype('int32'))
X = permute_dimensions(X, [0, 2, 3, 1])
X = tf.image.resize_bilinear(X, new_shape)
X = permute_dimensions(X, [0, 3, 1, 2])
if target_height and target_width:
X.set_shape((None, None, target_height, target_width))
else:
X.set_shape((None, None, original_shape[2] * height_factor,
original_shape[3] * width_factor))
return X
elif data_format == 'channels_last':
original_shape = K.int_shape(X)
if target_height and target_width:
new_shape = tf.constant(
np.array((target_height, target_width)).astype('int32'))
else:
new_shape = tf.shape(X)[1:3]
new_shape *= tf.constant(
np.array([height_factor, width_factor]).astype('int32'))
X = tf.image.resize_bilinear(X, new_shape)
if target_height and target_width:
X.set_shape((None, target_height, target_width, None))
else:
X.set_shape((None, original_shape[1] * height_factor,
original_shape[2] * width_factor, None))
return X
else:
raise Exception('Invalid data_format: ' + data_format)
def _call_multiplicative_emission(self, inputs):
# e_{t, t'} = x_t^T W_a x_{t'} + b_a
e = K.batch_dot(K.dot(inputs, self.Wa),
K.permute_dimensions(inputs, (0, 2, 1)))
if self.use_attention_bias:
e += self.ba[0]
return e
def gram_matrix(x):
assert K.ndim(x) == 3
if K.image_dim_ordering() == 'th':
features = K.batch_flatten(x)
else:
features = K.batch_flatten(K.permute_dimensions(x, (2, 0, 1)))
gram = K.dot(features - 1, K.transpose(features - 1))
return gram
def _attention_regularizer(self, attention):
batch_size = K.cast(K.shape(attention)[0], K.floatx())
input_len = K.shape(attention)[-1]
indices = K.expand_dims(K.arange(0, input_len), axis=0)
diagonal = K.expand_dims(K.arange(0, input_len), axis=-1)
eye = K.cast(K.equal(indices, diagonal), K.floatx())
return self.attention_regularizer_weight * K.sum(
K.square(
K.batch_dot(attention,
K.permute_dimensions(attention, (0, 2, 1))) -
eye)) / batch_size
def extract_image_patches(X,
ksizes,
ssizes,
border_mode="same",
dim_ordering="tf"):
'''
Extract the patches from an image
Parameters
----------
X : The input image
ksizes : 2-d tuple with the kernel size
ssizes : 2-d tuple with the strides size
border_mode : 'same' or 'valid'
dim_ordering : 'tf' or 'th'
Returns
-------
The (k_w,k_h) patches extracted
TF ==> (batch_size,w,h,k_w,k_h,c)
TH ==> (batch_size,w,h,c,k_w,k_h)
'''
kernel = [1, ksizes[0], ksizes[1], 1]
strides = [1, ssizes[0], ssizes[1], 1]
padding = _preprocess_border_mode(border_mode)
if dim_ordering == "th":
X = KTF.permute_dimensions(X, (0, 2, 3, 1))
bs_i, w_i, h_i, ch_i = KTF.int_shape(X)
patches = tf.extract_image_patches(X, kernel, strides, [1, 1, 1, 1],
padding)
# Reshaping to fit Theano
bs, w, h, ch = KTF.int_shape(patches)
patches = tf.reshape(
tf.transpose(tf.reshape(patches, [bs, w, h, -1, ch_i]),
[0, 1, 2, 4, 3]), [bs, w, h, ch_i, ksizes[0], ksizes[1]])
if dim_ordering == "tf":
patches = KTF.permute_dimensions(patches, [0, 1, 2, 4, 5, 3])
return patches
def call(self, inputs, mask=None, **kwargs):
input_len = K.shape(inputs)[1]
if self.attention_type == Attention.ATTENTION_TYPE_ADD:
e = self._call_additive_emission(inputs)
elif self.attention_type == Attention.ATTENTION_TYPE_MUL:
e = self._call_multiplicative_emission(inputs)
if self.attention_activation is not None:
e = self.attention_activation(e)
if self.attention_width is not None:
if self.history_only:
lower = K.arange(0, input_len) - (self.attention_width - 1)
else:
lower = K.arange(0, input_len) - self.attention_width // 2
lower = K.expand_dims(lower, axis=-1)
upper = lower + self.attention_width
indices = K.expand_dims(K.arange(0, input_len), axis=0)
e -= 10000.0 * (1.0 - K.cast(lower <= indices, K.floatx()) *
K.cast(indices < upper, K.floatx()))
if mask is not None:
mask = K.expand_dims(K.cast(mask, K.floatx()), axis=-1)
e -= 10000.0 * ((1.0 - mask) *
(1.0 - K.permute_dimensions(mask, (0, 2, 1))))
# a_{t} = \text{softmax}(e_t)
e = K.exp(e - K.max(e, axis=-1, keepdims=True))
a = e / K.sum(e, axis=-1, keepdims=True)
# l_t = \sum_{t'} a_{t, t'} x_{t'}
v = K.batch_dot(a, inputs)
if self.attention_regularizer_weight > 0.0:
self.add_loss(self._attention_regularizer(a))
if self.return_attention:
return [v, a]
return v
def extract_image_patches(X, ksizes, strides, rates, padding='valid', data_format='channels_first'):
'''
Extract the patches from an image
Parameters
----------
X : The input image
ksizes : 2-d tuple with the kernel size
strides : 2-d tuple with the strides size
padding : 'same' or 'valid'
data_format : 'channels_last' or 'channels_first'
Returns
-------
The (k_w,k_h) patches extracted
TF ==> (batch_size,w,h,k_w,k_h,c)
TH ==> (batch_size,w,h,c,k_w,k_h)
https://github.com/farizrahman4u/keras-contrib/blob/master/keras_contrib/backend/theano_backend.py
'''
if padding == 'same':
padding = 'ignore_borders'
if data_format == 'channels_first':
X = KTF.permute_dimensions(X, [0, 2, 3, 1])
# Thanks to https://github.com/awentzonline for the help!
patches = TF.extract_image_patches(X, ksizes, strides, rates, padding.upper())
return patches
def gram_matrix(x):
features = KTF.batch_flatten(KTF.permute_dimensions(x, (2, 0, 1)))
gram = KTF.dot(features, KTF.transpose(features))
return gram
