def yolo_head(graph, feats, anchors, num_classes):
with graph.as_default():
num_anchors = len(anchors)
anchors_tensor = K.reshape(K.variable(anchors),
[1, 1, 1, num_anchors, 2])
conv_dims = K.shape(feats)[1:3]
conv_height_index = K.arange(0, stop=conv_dims[0])
conv_width_index = K.arange(0, stop=conv_dims[1])
conv_height_index = K.tile(conv_height_index, [conv_dims[1]])
conv_width_index = K.tile(K.expand_dims(conv_width_index, 0),
[conv_dims[0], 1])
conv_width_index = K.flatten(K.transpose(conv_width_index))
conv_index = K.transpose(K.stack([conv_height_index,
conv_width_index]))
conv_index = K.reshape(conv_index,
[1, conv_dims[0], conv_dims[1], 1, 2])
conv_index = K.cast(conv_index, K.dtype(feats))
feats = K.reshape(
feats,
[-1, conv_dims[0], conv_dims[1], num_anchors, num_classes + 5])
conv_dims = K.cast(K.reshape(conv_dims, [1, 1, 1, 1, 2]),
K.dtype(feats))
box_xy = K.sigmoid(feats[..., :2])
box_wh = K.exp(feats[..., 2:4])
box_confidence = K.sigmoid(feats[..., 4:5])
box_class_probs = K.softmax(feats[..., 5:])
box_xy = (box_xy + conv_index) / conv_dims
box_wh = box_wh * anchors_tensor / conv_dims
return box_xy, box_wh, box_confidence, box_class_probs
def test_gradient(self):
val = np.random.random((4, 2))
xth = KTH.variable(val)
xtf = KTF.variable(val)
expth = xth * KTH.exp(xth)
exptf = xtf * KTF.exp(xtf)
lossth = KTH.sum(expth)
losstf = KTF.sum(exptf)
zero_lossth = KTH.stop_gradient(lossth)
zero_losstf = KTF.stop_gradient(losstf)
gradth = KTH.gradients(lossth, [expth])
gradtf = KTF.gradients(losstf, [exptf])
zero_gradth = KTH.gradients(lossth + zero_lossth, [expth])
zero_gradtf = KTF.gradients(losstf + zero_losstf, [exptf])
zth = KTH.eval(gradth[0])
ztf = KTF.eval(gradtf[0])
zero_zth = KTH.eval(zero_gradth[0])
zero_ztf = KTF.eval(zero_gradtf[0])
assert zth.shape == ztf.shape
assert zero_zth.shape == zero_ztf.shape
assert_allclose(zth, ztf, atol=1e-05)
assert_allclose(zero_zth, zero_ztf, atol=1e-05)
assert_allclose(zero_zth, zth, atol=1e-05)
assert_allclose(zero_ztf, ztf, atol=1e-05)
def test_gradient(self):
val = np.random.random((4, 2))
xth = KTH.variable(val)
xtf = KTF.variable(val)
expth = xth * KTH.exp(xth)
exptf = xtf * KTF.exp(xtf)
lossth = KTH.sum(expth)
losstf = KTF.sum(exptf)
zero_lossth = KTH.stop_gradient(lossth)
zero_losstf = KTF.stop_gradient(losstf)
gradth = KTH.gradients(lossth, [expth])
gradtf = KTF.gradients(losstf, [exptf])
zero_gradth = KTH.gradients(lossth + zero_lossth, [expth])
zero_gradtf = KTF.gradients(losstf + zero_losstf, [exptf])
zth = KTH.eval(gradth[0])
ztf = KTF.eval(gradtf[0])
zero_zth = KTH.eval(zero_gradth[0])
zero_ztf = KTF.eval(zero_gradtf[0])
assert zth.shape == ztf.shape
assert zero_zth.shape == zero_ztf.shape
assert_allclose(zth, ztf, atol=1e-05)
assert_allclose(zero_zth, zero_ztf, atol=1e-05)
assert_allclose(zero_zth, zth, atol=1e-05)
assert_allclose(zero_ztf, ztf, atol=1e-05)
def call(self, x, mask=None):
uit = dot_product(x, self.W)
if self.bias:
uit += self.b
uit = K.tanh(uit)
#ait = K.dot(uit, self.u)
ait = dot_product(uit, self.u)
a = K.exp(ait)
# apply mask after the exp. will be re-normalized next
if mask is not None:
# Cast the mask to floatX to avoid float64 upcasting in theano
a *= K.cast(mask, K.floatx())
# in some cases especially in the early stages of training the sum may be almost zero
# and this results in NaN's. A workaround is to add a very small positive number \epsilon to the sum.
# a /= K.cast(K.sum(a, axis=1, keepdims=True), K.floatx())
a /= K.cast(K.sum(a, axis=1, keepdims=True) + K.epsilon(), K.floatx())
a = K.expand_dims(a)
weighted_input = x * a
#return K.sum(weighted_input, axis=1)
print "here", weighted_input.shape
return weighted_input
def yolo_head(feats, anchors, num_classes, input_shape, calc_loss=False):
"""Convert final layer features to bounding box parameters."""
num_anchors = len(anchors)
# Reshape to batch, height, width, num_anchors, box_params.
anchors_tensor = K.reshape(K.constant(anchors), [1, 1, 1, num_anchors, 2])
grid_shape = K.shape(feats)[1:3] # height, width
grid_y = K.tile(K.reshape(K.arange(0, stop=grid_shape[0]), [-1, 1, 1, 1]),
[1, grid_shape[1], 1, 1])
grid_x = K.tile(K.reshape(K.arange(0, stop=grid_shape[1]), [1, -1, 1, 1]),
[grid_shape[0], 1, 1, 1])
grid = K.concatenate([grid_x, grid_y])
grid = K.cast(grid, K.dtype(feats))
feats = K.reshape(
feats,
[-1, grid_shape[0], grid_shape[1], num_anchors, num_classes + 5])
# Adjust preditions to each spatial grid point and anchor size.
box_xy = (K.sigmoid(feats[..., :2]) + grid) / K.cast(
grid_shape[::-1], K.dtype(feats))
box_wh = K.exp(feats[..., 2:4]) * anchors_tensor / K.cast(
input_shape[::-1], K.dtype(feats))
box_confidence = K.sigmoid(feats[..., 4:5])
box_class_probs = K.sigmoid(feats[..., 5:])
if calc_loss == True:
return grid, feats, box_xy, box_wh
return box_xy, box_wh, box_confidence, box_class_probs
def customLoss(yTrue, yPred):
weights = [assign_w, 1, 1, 1, 1, 1, 1, 1]
target = yTrue
# output = yPred
yPred /= tf.reduce_sum(yPred,
reduction_indices=len(yPred.get_shape()) - 1,
keep_dims=True)
# manual computation of crossentropy
epsilon = K._to_tensor(tf.keras.backend.epsilon(), yPred.dtype.base_dtype)
yPred = tf.clip_by_value(yPred, epsilon, 1. - epsilon)
# yPred = tf.log(yPred)
relu4 = keras.activations.relu(yPred, alpha=0.0, max_value=None, threshold=-4.1)
yPred = 1 / (1 + K.exp(-1 * gamma * (relu4)))
######apply weights here###############
mask = K.cast(K.expand_dims(weights, axis=-1), dtype='float32')
tensor_shape = yPred.get_shape()
# x = tf.add(x, tf.constant(1, shape=x.shape))
yPred_stack = []
for i in range(tensor_shape[1]):
mask_i = K.cast(K.expand_dims(mask[i], axis=-1), dtype='float32')
yPred_i = K.cast(K.expand_dims(yPred[:, i], axis=-1), dtype='float32')
yPred_stack.append(K.dot(yPred_i, mask_i))
output = tf.reshape(tf.stack(yPred_stack, axis=1, name='stack'), [-1, tensor_shape[1]])
return - tf.reduce_sum(target * output,
reduction_indices=len(output.get_shape()) - 1)
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 depth_softmax(matrix):
sigmoid = lambda x: 1 / (1 + K.exp(-x))
sigmoided_matrix = sigmoid(matrix)
softmax_matrix = sigmoided_matrix / K.sum(sigmoided_matrix, axis=-1, keepdims=True)
return softmax_matrix
def log_sum_exp(x, axis=None):
"""Log-sum-exp trick implementation"""
x_max = ktf.max(x, axis=axis, keepdims=True)
return ktf.log(ktf.sum(ktf.exp(x - x_max), axis=axis, keepdims=True))+x_max
def kernel(x):
return tf.exp(-0.5 * (x - mu) * (x - mu) / sigma / sigma)
def customLoss(yTrue, yPred):
relu4 = keras.activations.relu(yPred, alpha=0.0, max_value=None, threshold=-4.1)
sigmoid5 = 1 / (1 + K.exp(-1 * GAMMA * (relu4)))
return -(yTrue * sigmoid5 + (1 - yTrue) * (1 - sigmoid5))
