def loss_without_regularization(self, y_true, y_pred):
"""
squeezeDet loss function for object detection and classification
:param y_true: ground truth with shape [batchsize, #anchors, classes+8+labels]
:param y_pred:
:return: a tensor of the total loss
"""
mc = self.config
input_mask = y_true[:, :, 0]
input_mask = K.expand_dims(input_mask, axis=-1)
box_input = y_true[:, :, 1:5]
box_delta_input = y_true[:, :, 5:9]
labels = y_true[:, :, 9:]
num_objects = K.sum(input_mask)
pred_class_probs, pred_conf, pred_box_delta = utils.slice_predictions(
y_pred, mc)
det_boxes = utils.boxes_from_deltas(pred_box_delta, mc)
unstacked_boxes_pred = []
unstacked_boxes_input = []
for i in range(4):
unstacked_boxes_pred.append(det_boxes[:, :, i])
unstacked_boxes_input.append(box_input[:, :, i])
ious = utils.tensor_iou(utils.bbox_transform(unstacked_boxes_pred),
utils.bbox_transform(unstacked_boxes_input),
input_mask, mc)
class_loss = K.sum(labels * (-K.log(pred_class_probs + mc.EPSILON)) +
(1 - labels) *
(-K.log(1 - pred_class_probs + mc.EPSILON)) *
input_mask * mc.LOSS_COEF_CLASS) / num_objects
bbox_loss = (K.sum(
mc.LOSS_COEF_BBOX * K.square(input_mask *
(pred_box_delta - box_delta_input))) /
num_objects)
input_mask = K.reshape(input_mask, [mc.BATCH_SIZE, mc.ANCHORS])
conf_loss = K.mean(
K.sum(K.square((ious - pred_conf)) *
(input_mask * mc.LOSS_COEF_CONF_POS / num_objects +
(1 - input_mask) * mc.LOSS_COEF_CONF_NEG /
(mc.ANCHORS - num_objects)),
axis=[1]), )
total_loss = class_loss + conf_loss + bbox_loss
return total_loss
def loss_without_regularization(self, y_true, y_pred):
"""
squeezeDet loss function for object detection and classification
:param y_true: ground truth with shape [batchsize, #anchors, classes+8+labels]
:param y_pred:
:return: a tensor of the total loss
"""
#handle for config
mc = self.config
#slice y_true
input_mask = y_true[:, :, 0]
input_mask = K.expand_dims(input_mask, axis=-1)
box_input = y_true[:, :, 1:5]
box_delta_input = y_true[:, :, 5:9]
labels = y_true[:, :, 9:]
#number of objects. Used to normalize bbox and classification loss
num_objects = K.sum(input_mask)
#before computing the losses we need to slice the network outputs
pred_class_probs, pred_conf, pred_box_delta = utils.slice_predictions(
y_pred, mc)
#compute boxes
det_boxes = utils.boxes_from_deltas(pred_box_delta, mc)
#again unstack is not avaible in pure keras backend
unstacked_boxes_pred = []
unstacked_boxes_input = []
for i in range(4):
unstacked_boxes_pred.append(det_boxes[:, :, i])
unstacked_boxes_input.append(box_input[:, :, i])
#compute the ious
ious = utils.tensor_iou(utils.bbox_transform(unstacked_boxes_pred),
utils.bbox_transform(unstacked_boxes_input),
input_mask, mc)
# cross-entropy: q * -log(p) + (1-q) * -log(1-p)
# add a small value into log to prevent blowing up
#compute class loss
class_loss = K.sum(labels * (-K.log(pred_class_probs + mc.EPSILON)) +
(1 - labels) *
(-K.log(1 - pred_class_probs + mc.EPSILON)) *
input_mask * mc.LOSS_COEF_CLASS) / num_objects
#bounding box loss
bbox_loss = (K.sum(
mc.LOSS_COEF_BBOX * K.square(input_mask *
(pred_box_delta - box_delta_input))) /
num_objects)
#reshape input for correct broadcasting
input_mask = K.reshape(input_mask, [mc.BATCH_SIZE, mc.ANCHORS])
#confidence score loss
conf_loss = K.mean(
K.sum(K.square((ious - pred_conf)) *
(input_mask * mc.LOSS_COEF_CONF_POS / num_objects +
(1 - input_mask) * mc.LOSS_COEF_CONF_NEG /
(mc.ANCHORS - num_objects)),
axis=[1]), )
# add above losses
total_loss = class_loss + conf_loss + bbox_loss
return total_loss
