def call(self, x, mask=None):
'''
Return an anchor box tensor based on the shape of the input tensor.
The logic implemented here is identical to the logic in the module `ssd_box_encode_decode_utils.py`.
Note that this tensor does not participate in any graph computations at runtime. It is being created
as a constant once during graph creation and is just being output along with the rest of the model output
during runtime. Because of this, all logic is implemented as Numpy array operations and it is sufficient
to convert the resulting Numpy array into a Keras tensor at the very end before outputting it.
Arguments:
x (tensor): 4D tensor of shape `(batch, channels, height, width)` if `dim_ordering = 'th'`
or `(batch, height, width, channels)` if `dim_ordering = 'tf'`. The input for this
layer must be the output of the localization predictor layer.
'''
# Compute box width and height for each aspect ratio
# The shorter side of the image will be used to compute `w` and `h` using `scale` and `aspect_ratios`.
size = min(self.img_height, self.img_width)
# Compute the box widths and and heights for all aspect ratios
wh_list = []
for ar in self.aspect_ratios:
if (ar == 1):
# Compute the regular anchor box for aspect ratio 1.
box_height = box_width = self.this_scale * size
wh_list.append((box_width, box_height))
if self.two_boxes_for_ar1:
# Compute one slightly larger version using the geometric mean of this scale value and the next.
box_height = box_width = np.sqrt(
self.this_scale * self.next_scale) * size
wh_list.append((box_width, box_height))
else:
box_height = self.this_scale * size / np.sqrt(ar)
box_width = self.this_scale * size * np.sqrt(ar)
wh_list.append((box_width, box_height))
wh_list = np.array(wh_list)
# We need the shape of the input tensor
if K.image_dim_ordering() == 'tf':
batch_size, feature_map_height, feature_map_width, feature_map_channels = x._keras_shape
else: # Not yet relevant since TensorFlow is the only supported backend right now, but it can't harm to have this in here for the future
batch_size, feature_map_channels, feature_map_height, feature_map_width = x._keras_shape
# Compute the grid of box center points. They are identical for all aspect ratios.
# Compute the step sizes, i.e. how far apart the anchor box center points will be vertically and horizontally.
if (self.this_steps is None):
step_height = self.img_height / feature_map_height
step_width = self.img_width / feature_map_width
else:
if isinstance(self.this_steps,
(list, tuple)) and (len(self.this_steps) == 2):
step_height = self.this_steps[0]
step_width = self.this_steps[1]
elif isinstance(self.this_steps, (int, float)):
step_height = self.this_steps
step_width = self.this_steps
# Compute the offsets, i.e. at what pixel values the first anchor box center point will be from the top and from the left of the image.
if (self.this_offsets is None):
offset_height = 0.5
offset_width = 0.5
else:
if isinstance(self.this_offsets,
(list, tuple)) and (len(self.this_offsets) == 2):
offset_height = self.this_offsets[0]
offset_width = self.this_offsets[0]
elif isinstance(self.this_offsets, (int, float)):
offset_height = self.this_offsets
offset_width = self.this_offsets
# Now that we have the offsets and step sizes, compute the grid of anchor box center points.
cy = np.linspace(offset_height * step_height,
(offset_height + feature_map_height - 1) *
step_height, feature_map_height)
cx = np.linspace(offset_width * step_width,
(offset_width + feature_map_width - 1) * step_width,
feature_map_width)
cx_grid, cy_grid = np.meshgrid(cx, cy)
cx_grid = np.expand_dims(
cx_grid, -1
) # This is necessary for np.tile() to do what we want further down
cy_grid = np.expand_dims(
cy_grid, -1
) # This is necessary for np.tile() to do what we want further down
# Create a 4D tensor template of shape `(feature_map_height, feature_map_width, n_boxes, 4)`
# where the last dimension will contain `(cx, cy, w, h)`
boxes_tensor = np.zeros(
(feature_map_height, feature_map_width, self.n_boxes, 4))
boxes_tensor[:, :, :, 0] = np.tile(cx_grid,
(1, 1, self.n_boxes)) # Set cx
boxes_tensor[:, :, :, 1] = np.tile(cy_grid,
(1, 1, self.n_boxes)) # Set cy
boxes_tensor[:, :, :, 2] = wh_list[:, 0] # Set w
boxes_tensor[:, :, :, 3] = wh_list[:, 1] # Set h
# Convert `(cx, cy, w, h)` to `(xmin, xmax, ymin, ymax)`
boxes_tensor = convert_coordinates(boxes_tensor,
start_index=0,
conversion='centroids2corners')
# If `limit_boxes` is enabled, clip the coordinates to lie within the image boundaries
if self.limit_boxes:
x_coords = boxes_tensor[:, :, :, [0, 2]]
x_coords[x_coords >= self.img_width] = self.img_width - 1
x_coords[x_coords < 0] = 0
boxes_tensor[:, :, :, [0, 2]] = x_coords
y_coords = boxes_tensor[:, :, :, [1, 3]]
y_coords[y_coords >= self.img_height] = self.img_height - 1
y_coords[y_coords < 0] = 0
boxes_tensor[:, :, :, [1, 3]] = y_coords
# If `normalize_coords` is enabled, normalize the coordinates to be within [0,1]
if self.normalize_coords:
boxes_tensor[:, :, :, [0, 2]] /= self.img_width
boxes_tensor[:, :, :, [1, 3]] /= self.img_height
# TODO: Implement box limiting directly for `(cx, cy, w, h)` so that we don't have to unnecessarily convert back and forth.
if self.coords == 'centroids':
# Convert `(xmin, ymin, xmax, ymax)` back to `(cx, cy, w, h)`.
boxes_tensor = convert_coordinates(boxes_tensor,
start_index=0,
conversion='corners2centroids')
elif self.coords == 'minmax':
# Convert `(xmin, ymin, xmax, ymax)` to `(xmin, xmax, ymin, ymax).
boxes_tensor = convert_coordinates(boxes_tensor,
start_index=0,
conversion='corners2minmax')
# Create a tensor to contain the variances and append it to `boxes_tensor`. This tensor has the same shape
# as `boxes_tensor` and simply contains the same 4 variance values for every position in the last axis.
variances_tensor = np.zeros_like(
boxes_tensor
) # Has shape `(feature_map_height, feature_map_width, n_boxes, 4)`
variances_tensor += self.variances # Long live broadcasting
# Now `boxes_tensor` becomes a tensor of shape `(feature_map_height, feature_map_width, n_boxes, 8)`
boxes_tensor = np.concatenate((boxes_tensor, variances_tensor),
axis=-1)
# Now prepend one dimension to `boxes_tensor` to account for the batch size and tile it along
# The result will be a 5D tensor of shape `(batch_size, feature_map_height, feature_map_width, n_boxes, 8)`
boxes_tensor = np.expand_dims(boxes_tensor, axis=0)
boxes_tensor = K.tile(K.constant(boxes_tensor, dtype='float32'),
(K.shape(x)[0], 1, 1, 1, 1))
return boxes_tensor
def call(self, x, mask=None):
'''
Return an anchor box tensor based on the input tensor.
The logic implemented here is identical to the logic in the module `ssd_box_encode_decode_utils.py`.
Note that this tensor does not participate in any graph computations at runtime. It is being created
as a constant once for each classification conv layer during graph creation and is just being output
along with the rest of the model output during runtime. Because of this, all logic is implemented
as Numpy array operations and it is sufficient to convert the resulting Numpy array into a Keras tensor
at the very end before outputting it.
'''
# Compute box width and height for each aspect ratio
# The shorter side of the image will be used to compute `w` and `h` using `scale` and `aspect_ratios`.
self.aspect_ratios = np.sort(self.aspect_ratios)
size = min(self.img_height, self.img_width)
# Compute the box widths and and heights for all aspect ratios
wh_list = []
for ar in self.aspect_ratios:
if (ar == 1) & self.two_boxes_for_ar1:
# Compute the regular default box for aspect ratio 1 and...
w = self.this_scale * size * np.sqrt(ar)
h = self.this_scale * size / np.sqrt(ar)
wh_list.append((w,h))
# ...also compute one slightly larger version using the geometric mean of this scale value and the next
w = np.sqrt(self.this_scale * self.next_scale) * size * np.sqrt(ar)
h = np.sqrt(self.this_scale * self.next_scale) * size / np.sqrt(ar)
wh_list.append((w,h))
else:
w = self.this_scale * size * np.sqrt(ar)
h = self.this_scale * size / np.sqrt(ar)
wh_list.append((w,h))
wh_list = np.array(wh_list)
# We need the shape of the input tensor
if K.image_dim_ordering() == 'tf':
batch_size, feature_map_height, feature_map_width, feature_map_channels = x._keras_shape
else: # Not yet relevant since TensorFlow is the only supported backend right now, but it can't harm to have this in here for the future
batch_size, feature_map_channels, feature_map_height, feature_map_width = x._keras_shape
# Compute the grid of box center points. They are identical for all aspect ratios
cell_height = self.img_height / feature_map_height
cell_width = self.img_width / feature_map_width
cx = np.linspace(cell_width/2, self.img_width-cell_width/2, feature_map_width)
cy = np.linspace(cell_height/2, self.img_height-cell_height/2, feature_map_height)
cx_grid, cy_grid = np.meshgrid(cx, cy)
cx_grid = np.expand_dims(cx_grid, -1) # This is necessary for np.tile() to do what we want further down
cy_grid = np.expand_dims(cy_grid, -1) # This is necessary for np.tile() to do what we want further down
# Create a 4D tensor template of shape `(feature_map_height, feature_map_width, n_boxes, 4)`
# where the last dimension will contain `(cx, cy, w, h)`
boxes_tensor = np.zeros((feature_map_height, feature_map_width, self.n_boxes, 4))
boxes_tensor[:, :, :, 0] = np.tile(cx_grid, (1, 1, self.n_boxes)) # Set cx
boxes_tensor[:, :, :, 1] = np.tile(cy_grid, (1, 1, self.n_boxes)) # Set cy
boxes_tensor[:, :, :, 2] = wh_list[:, 0] # Set w
boxes_tensor[:, :, :, 3] = wh_list[:, 1] # Set h
# Convert `(cx, cy, w, h)` to `(xmin, xmax, ymin, ymax)`
boxes_tensor = convert_coordinates(boxes_tensor, start_index=0, conversion='centroids2minmax')
# If `limit_boxes` is enabled, clip the coordinates to lie within the image boundaries
if self.limit_boxes:
x_coords = boxes_tensor[:,:,:,[0, 1]]
x_coords[x_coords >= self.img_width] = self.img_width - 1
x_coords[x_coords < 0] = 0
boxes_tensor[:,:,:,[0, 1]] = x_coords
y_coords = boxes_tensor[:,:,:,[2, 3]]
y_coords[y_coords >= self.img_height] = self.img_height - 1
y_coords[y_coords < 0] = 0
boxes_tensor[:,:,:,[2, 3]] = y_coords
# `normalize_coords` is enabled, normalize the coordinates to be within [0,1]
if self.normalize_coords:
boxes_tensor[:, :, :, :2] /= self.img_width
boxes_tensor[:, :, :, 2:] /= self.img_height
if self.coords == 'centroids':
# TODO: Implement box limiting directly for `(cx, cy, w, h)` so that we don't have to unnecessarily convert back and forth
# Convert `(xmin, xmax, ymin, ymax)` back to `(cx, cy, w, h)`
boxes_tensor = convert_coordinates(boxes_tensor, start_index=0, conversion='minmax2centroids')
# 4: Create a tensor to contain the variances and append it to `boxes_tensor`. This tensor has the same shape
# as `boxes_tensor` and simply contains the same 4 variance values for every position in the last axis.
variances_tensor = np.zeros_like(boxes_tensor) # Has shape `(feature_map_height, feature_map_width, n_boxes, 4)`
variances_tensor += self.variances # Long live broadcasting
# Now `boxes_tensor` becomes a tensor of shape `(feature_map_height, feature_map_width, n_boxes, 8)`
boxes_tensor = np.concatenate((boxes_tensor, variances_tensor), axis=-1)
# Now prepend one dimension to `boxes_tensor` to account for the batch size and tile it along
# The result will be a 5D tensor of shape `(batch_size, feature_map_height, feature_map_width, n_boxes, 8)`
boxes_tensor = np.expand_dims(boxes_tensor, axis=0)
boxes_tensor = K.tile(K.constant(boxes_tensor, dtype='float32'), (K.shape(x)[0], 1, 1, 1, 1))
return boxes_tensor
def call(self, x, mask=None):
'''
Return an anchor box tensor based on the shape of the input tensor.
The logic implemented here is identical to the logic in the module `ssd_box_encode_decode_utils.py`.
Note that this tensor does not participate in any graph computations at runtime. It is being created
as a constant once during graph creation and is just being output along with the rest of the model output
during runtime. Because of this, all logic is implemented as Numpy array operations and it is sufficient
to convert the resulting Numpy array into a Keras tensor at the very end before outputting it.
Arguments:
x (tensor): 4D tensor of shape `(batch, channels, height, width)` if `dim_ordering = 'th'`
or `(batch, height, width, channels)` if `dim_ordering = 'tf'`. The input for this
layer must be the output of the localization predictor layer.
'''
# Compute box width and height for each aspect ratio
# The shorter side of the image will be used to compute `w` and `h` using `scale` and `aspect_ratios`.
self.aspect_ratios = np.sort(self.aspect_ratios)
size = min(self.img_height, self.img_width)
# Compute the box widths and and heights for all aspect ratios
wh_list = []
for ar in self.aspect_ratios:
if (ar == 1) & self.two_boxes_for_ar1:
# Compute the regular default box for aspect ratio 1 and...
w = self.this_scale * size * np.sqrt(ar)
h = self.this_scale * size / np.sqrt(ar)
wh_list.append((w,h))
# ...also compute one slightly larger version using the geometric mean of this scale value and the next
w = np.sqrt(self.this_scale * self.next_scale) * size * np.sqrt(ar)
h = np.sqrt(self.this_scale * self.next_scale) * size / np.sqrt(ar)
wh_list.append((w,h))
else:
w = self.this_scale * size * np.sqrt(ar)
h = self.this_scale * size / np.sqrt(ar)
wh_list.append((w,h))
wh_list = np.array(wh_list)
# We need the shape of the input tensor
if K.image_dim_ordering() == 'tf':
batch_size, feature_map_height, feature_map_width, feature_map_channels = x._keras_shape
else: # Not yet relevant since TensorFlow is the only supported backend right now, but it can't harm to have this in here for the future
batch_size, feature_map_channels, feature_map_height, feature_map_width = x._keras_shape
# Compute the grid of box center points. They are identical for all aspect ratios
cell_height = self.img_height / feature_map_height
cell_width = self.img_width / feature_map_width
cx = np.linspace(cell_width/2, self.img_width-cell_width/2, feature_map_width)
cy = np.linspace(cell_height/2, self.img_height-cell_height/2, feature_map_height)
cx_grid, cy_grid = np.meshgrid(cx, cy)
cx_grid = np.expand_dims(cx_grid, -1) # This is necessary for np.tile() to do what we want further down
cy_grid = np.expand_dims(cy_grid, -1) # This is necessary for np.tile() to do what we want further down
# Create a 4D tensor template of shape `(feature_map_height, feature_map_width, n_boxes, 4)`
# where the last dimension will contain `(cx, cy, w, h)`
boxes_tensor = np.zeros((feature_map_height, feature_map_width, self.n_boxes, 4))
boxes_tensor[:, :, :, 0] = np.tile(cx_grid, (1, 1, self.n_boxes)) # Set cx
boxes_tensor[:, :, :, 1] = np.tile(cy_grid, (1, 1, self.n_boxes)) # Set cy
boxes_tensor[:, :, :, 2] = wh_list[:, 0] # Set w
boxes_tensor[:, :, :, 3] = wh_list[:, 1] # Set h
# Convert `(cx, cy, w, h)` to `(xmin, xmax, ymin, ymax)`
boxes_tensor = convert_coordinates(boxes_tensor, start_index=0, conversion='centroids2minmax')
# If `limit_boxes` is enabled, clip the coordinates to lie within the image boundaries
if self.limit_boxes:
x_coords = boxes_tensor[:,:,:,[0, 1]]
x_coords[x_coords >= self.img_width] = self.img_width - 1
x_coords[x_coords < 0] = 0
boxes_tensor[:,:,:,[0, 1]] = x_coords
y_coords = boxes_tensor[:,:,:,[2, 3]]
y_coords[y_coords >= self.img_height] = self.img_height - 1
y_coords[y_coords < 0] = 0
boxes_tensor[:,:,:,[2, 3]] = y_coords
# `normalize_coords` is enabled, normalize the coordinates to be within [0,1]
if self.normalize_coords:
boxes_tensor[:, :, :, :2] /= self.img_width
boxes_tensor[:, :, :, 2:] /= self.img_height
if self.coords == 'centroids':
# TODO: Implement box limiting directly for `(cx, cy, w, h)` so that we don't have to unnecessarily convert back and forth
# Convert `(xmin, xmax, ymin, ymax)` back to `(cx, cy, w, h)`
boxes_tensor = convert_coordinates(boxes_tensor, start_index=0, conversion='minmax2centroids')
# 4: Create a tensor to contain the variances and append it to `boxes_tensor`. This tensor has the same shape
# as `boxes_tensor` and simply contains the same 4 variance values for every position in the last axis.
variances_tensor = np.zeros_like(boxes_tensor) # Has shape `(feature_map_height, feature_map_width, n_boxes, 4)`
variances_tensor += self.variances # Long live broadcasting
# Now `boxes_tensor` becomes a tensor of shape `(feature_map_height, feature_map_width, n_boxes, 8)`
boxes_tensor = np.concatenate((boxes_tensor, variances_tensor), axis=-1)
# Now prepend one dimension to `boxes_tensor` to account for the batch size and tile it along
# The result will be a 5D tensor of shape `(batch_size, feature_map_height, feature_map_width, n_boxes, 8)`
boxes_tensor = np.expand_dims(boxes_tensor, axis=0)
boxes_tensor = K.tile(K.constant(boxes_tensor, dtype='float32'), (K.shape(x)[0], 1, 1, 1, 1))
return boxes_tensor
