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frontend.py
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from keras.models import Model
from keras.layers import Reshape, Activation, Conv2D, Input, MaxPooling2D, BatchNormalization, Flatten, Dense, Lambda
from keras.layers.advanced_activations import LeakyReLU
import tensorflow as tf
import numpy as np
import os
import cv2
from utils import decode_netout, compute_overlap, compute_ap
from keras.applications.mobilenet import MobileNet
from keras.layers.merge import concatenate
from keras.optimizers import SGD, Adam, RMSprop
from preprocessing import BatchGenerator
from keras.callbacks import EarlyStopping, ModelCheckpoint, TensorBoard
from backend import TinyYoloFeature, FullYoloFeature, MobileNetFeature, SqueezeNetFeature, Inception3Feature, VGG16Feature, ResNet50Feature
class YOLO(object):
def __init__(self, backend,
input_size,
labels,
max_box_per_image,
anchors):
self.input_size = input_size
self.labels = list(labels)
self.nb_class = len(self.labels)
self.nb_box = len(anchors)//2
self.class_wt = np.ones(self.nb_class, dtype='float32')
self.anchors = anchors
self.max_box_per_image = max_box_per_image
##########################
# Make the model
##########################
# make the feature extractor layers
input_image = Input(shape=(self.input_size, self.input_size, 3))
self.true_boxes = Input(shape=(1, 1, 1, max_box_per_image , 4))
if backend == 'Inception3':
self.feature_extractor = Inception3Feature(self.input_size)
elif backend == 'SqueezeNet':
self.feature_extractor = SqueezeNetFeature(self.input_size)
elif backend == 'MobileNet':
self.feature_extractor = MobileNetFeature(self.input_size)
elif backend == 'Full Yolo':
self.feature_extractor = FullYoloFeature(self.input_size)
elif backend == 'Tiny Yolo':
self.feature_extractor = TinyYoloFeature(self.input_size)
elif backend == 'VGG16':
self.feature_extractor = VGG16Feature(self.input_size)
elif backend == 'ResNet50':
self.feature_extractor = ResNet50Feature(self.input_size)
else:
raise Exception('Architecture not supported! Only support Full Yolo, Tiny Yolo, MobileNet, SqueezeNet, VGG16, ResNet50, and Inception3 at the moment!')
print(self.feature_extractor.get_output_shape())
self.grid_h, self.grid_w = self.feature_extractor.get_output_shape()
features = self.feature_extractor.extract(input_image)
# make the object detection layer
output = Conv2D(self.nb_box * (4 + 1 + self.nb_class),
(1,1), strides=(1,1),
padding='same',
name='DetectionLayer',
kernel_initializer='lecun_normal')(features)
output = Reshape((self.grid_h, self.grid_w, self.nb_box, 4 + 1 + self.nb_class))(output)
output = Lambda(lambda args: args[0])([output, self.true_boxes])
self.model = Model([input_image, self.true_boxes], output)
# initialize the weights of the detection layer
layer = self.model.layers[-4]
weights = layer.get_weights()
new_kernel = np.random.normal(size=weights[0].shape)/(self.grid_h*self.grid_w)
new_bias = np.random.normal(size=weights[1].shape)/(self.grid_h*self.grid_w)
layer.set_weights([new_kernel, new_bias])
# print a summary of the whole model
self.model.summary()
def custom_loss(self, y_true, y_pred):
mask_shape = tf.shape(y_true)[:4]
cell_x = tf.to_float(tf.reshape(tf.tile(tf.range(self.grid_w), [self.grid_h]), (1, self.grid_h, self.grid_w, 1, 1)))
cell_y = tf.transpose(cell_x, (0,2,1,3,4))
cell_grid = tf.tile(tf.concat([cell_x,cell_y], -1), [self.batch_size, 1, 1, self.nb_box, 1])
coord_mask = tf.zeros(mask_shape)
conf_mask = tf.zeros(mask_shape)
class_mask = tf.zeros(mask_shape)
seen = tf.Variable(0.)
total_recall = tf.Variable(0.)
"""
Adjust prediction
"""
### adjust x and y
pred_box_xy = tf.sigmoid(y_pred[..., :2]) + cell_grid
### adjust w and h
pred_box_wh = tf.exp(y_pred[..., 2:4]) * np.reshape(self.anchors, [1,1,1,self.nb_box,2])
### adjust confidence
pred_box_conf = tf.sigmoid(y_pred[..., 4])
### adjust class probabilities
pred_box_class = y_pred[..., 5:]
"""
Adjust ground truth
"""
### adjust x and y
true_box_xy = y_true[..., 0:2] # relative position to the containing cell
### adjust w and h
true_box_wh = y_true[..., 2:4] # number of cells accross, horizontally and vertically
### adjust confidence
true_wh_half = true_box_wh / 2.
true_mins = true_box_xy - true_wh_half
true_maxes = true_box_xy + true_wh_half
pred_wh_half = pred_box_wh / 2.
pred_mins = pred_box_xy - pred_wh_half
pred_maxes = pred_box_xy + pred_wh_half
intersect_mins = tf.maximum(pred_mins, true_mins)
intersect_maxes = tf.minimum(pred_maxes, true_maxes)
intersect_wh = tf.maximum(intersect_maxes - intersect_mins, 0.)
intersect_areas = intersect_wh[..., 0] * intersect_wh[..., 1]
true_areas = true_box_wh[..., 0] * true_box_wh[..., 1]
pred_areas = pred_box_wh[..., 0] * pred_box_wh[..., 1]
union_areas = pred_areas + true_areas - intersect_areas
iou_scores = tf.truediv(intersect_areas, union_areas)
true_box_conf = iou_scores * y_true[..., 4]
### adjust class probabilities
true_box_class = tf.argmax(y_true[..., 5:], -1)
"""
Determine the masks
"""
### coordinate mask: simply the position of the ground truth boxes (the predictors)
coord_mask = tf.expand_dims(y_true[..., 4], axis=-1) * self.coord_scale
### confidence mask: penelize predictors + penalize boxes with low IOU
# penalize the confidence of the boxes, which have IOU with some ground truth box < 0.6
true_xy = self.true_boxes[..., 0:2]
true_wh = self.true_boxes[..., 2:4]
true_wh_half = true_wh / 2.
true_mins = true_xy - true_wh_half
true_maxes = true_xy + true_wh_half
pred_xy = tf.expand_dims(pred_box_xy, 4)
pred_wh = tf.expand_dims(pred_box_wh, 4)
pred_wh_half = pred_wh / 2.
pred_mins = pred_xy - pred_wh_half
pred_maxes = pred_xy + pred_wh_half
intersect_mins = tf.maximum(pred_mins, true_mins)
intersect_maxes = tf.minimum(pred_maxes, true_maxes)
intersect_wh = tf.maximum(intersect_maxes - intersect_mins, 0.)
intersect_areas = intersect_wh[..., 0] * intersect_wh[..., 1]
true_areas = true_wh[..., 0] * true_wh[..., 1]
pred_areas = pred_wh[..., 0] * pred_wh[..., 1]
union_areas = pred_areas + true_areas - intersect_areas
iou_scores = tf.truediv(intersect_areas, union_areas)
best_ious = tf.reduce_max(iou_scores, axis=4)
conf_mask = conf_mask + tf.to_float(best_ious < 0.6) * (1 - y_true[..., 4]) * self.no_object_scale
# penalize the confidence of the boxes, which are reponsible for corresponding ground truth box
conf_mask = conf_mask + y_true[..., 4] * self.object_scale
### class mask: simply the position of the ground truth boxes (the predictors)
class_mask = y_true[..., 4] * tf.gather(self.class_wt, true_box_class) * self.class_scale
"""
Warm-up training
"""
no_boxes_mask = tf.to_float(coord_mask < self.coord_scale/2.)
seen = tf.assign_add(seen, 1.)
true_box_xy, true_box_wh, coord_mask = tf.cond(tf.less(seen, self.warmup_batches+1),
lambda: [true_box_xy + (0.5 + cell_grid) * no_boxes_mask,
true_box_wh + tf.ones_like(true_box_wh) * \
np.reshape(self.anchors, [1,1,1,self.nb_box,2]) * \
no_boxes_mask,
tf.ones_like(coord_mask)],
lambda: [true_box_xy,
true_box_wh,
coord_mask])
"""
Finalize the loss
"""
nb_coord_box = tf.reduce_sum(tf.to_float(coord_mask > 0.0))
nb_conf_box = tf.reduce_sum(tf.to_float(conf_mask > 0.0))
nb_class_box = tf.reduce_sum(tf.to_float(class_mask > 0.0))
loss_xy = tf.reduce_sum(tf.square(true_box_xy-pred_box_xy) * coord_mask) / (nb_coord_box + 1e-6) / 2.
loss_wh = tf.reduce_sum(tf.square(true_box_wh-pred_box_wh) * coord_mask) / (nb_coord_box + 1e-6) / 2.
loss_conf = tf.reduce_sum(tf.square(true_box_conf-pred_box_conf) * conf_mask) / (nb_conf_box + 1e-6) / 2.
loss_class = tf.nn.sparse_softmax_cross_entropy_with_logits(labels=true_box_class, logits=pred_box_class)
loss_class = tf.reduce_sum(loss_class * class_mask) / (nb_class_box + 1e-6)
loss = tf.cond(tf.less(seen, self.warmup_batches+1),
lambda: loss_xy + loss_wh + loss_conf + loss_class + 10,
lambda: loss_xy + loss_wh + loss_conf + loss_class)
if self.debug:
nb_true_box = tf.reduce_sum(y_true[..., 4])
nb_pred_box = tf.reduce_sum(tf.to_float(true_box_conf > 0.5) * tf.to_float(pred_box_conf > 0.3))
current_recall = nb_pred_box/(nb_true_box + 1e-6)
total_recall = tf.assign_add(total_recall, current_recall)
loss = tf.Print(loss, [loss_xy], message='Loss XY \t', summarize=1000)
loss = tf.Print(loss, [loss_wh], message='Loss WH \t', summarize=1000)
loss = tf.Print(loss, [loss_conf], message='Loss Conf \t', summarize=1000)
loss = tf.Print(loss, [loss_class], message='Loss Class \t', summarize=1000)
loss = tf.Print(loss, [loss], message='Total Loss \t', summarize=1000)
loss = tf.Print(loss, [current_recall], message='Current Recall \t', summarize=1000)
loss = tf.Print(loss, [total_recall/seen], message='Average Recall \t', summarize=1000)
return loss
def load_weights(self, weight_path):
self.model.load_weights(weight_path)
def train(self, train_imgs, # the list of images to train the model
valid_imgs, # the list of images used to validate the model
train_times, # the number of time to repeat the training set, often used for small datasets
valid_times, # the number of times to repeat the validation set, often used for small datasets
nb_epochs, # number of epoches
learning_rate, # the learning rate
batch_size, # the size of the batch
warmup_epochs, # number of initial batches to let the model familiarize with the new dataset
object_scale,
no_object_scale,
coord_scale,
class_scale,
saved_weights_name='best_weights.h5',
debug=False):
self.batch_size = batch_size
self.object_scale = object_scale
self.no_object_scale = no_object_scale
self.coord_scale = coord_scale
self.class_scale = class_scale
self.debug = debug
############################################
# Make train and validation generators
############################################
generator_config = {
'IMAGE_H' : self.input_size,
'IMAGE_W' : self.input_size,
'GRID_H' : self.grid_h,
'GRID_W' : self.grid_w,
'BOX' : self.nb_box,
'LABELS' : self.labels,
'CLASS' : len(self.labels),
'ANCHORS' : self.anchors,
'BATCH_SIZE' : self.batch_size,
'TRUE_BOX_BUFFER' : self.max_box_per_image,
}
train_generator = BatchGenerator(train_imgs,
generator_config,
norm=self.feature_extractor.normalize)
valid_generator = BatchGenerator(valid_imgs,
generator_config,
norm=self.feature_extractor.normalize,
jitter=False)
self.warmup_batches = warmup_epochs * (train_times*len(train_generator) + valid_times*len(valid_generator))
############################################
# Compile the model
############################################
optimizer = Adam(lr=learning_rate, beta_1=0.9, beta_2=0.999, epsilon=1e-08, decay=0.0)
self.model.compile(loss=self.custom_loss, optimizer=optimizer)
############################################
# Make a few callbacks
############################################
early_stop = EarlyStopping(monitor='val_loss',
min_delta=0.001,
patience=3,
mode='min',
verbose=1)
checkpoint = ModelCheckpoint(saved_weights_name,
monitor='val_loss',
verbose=1,
save_best_only=True,
mode='min',
period=1)
tensorboard = TensorBoard(log_dir=os.path.expanduser('~/logs/'),
histogram_freq=0,
#write_batch_performance=True,
write_graph=True,
write_images=False)
############################################
# Start the training process
############################################
self.model.fit_generator(generator = train_generator,
steps_per_epoch = len(train_generator) * train_times,
epochs = warmup_epochs + nb_epochs,
verbose = 2 if debug else 1,
validation_data = valid_generator,
validation_steps = len(valid_generator) * valid_times,
callbacks = [early_stop, checkpoint, tensorboard],
workers = 3,
max_queue_size = 8)
############################################
# Compute mAP on the validation set
############################################
average_precisions = self.evaluate(valid_generator)
# print evaluation
for label, average_precision in average_precisions.items():
print(self.labels[label], '{:.4f}'.format(average_precision))
print('mAP: {:.4f}'.format(sum(average_precisions.values()) / len(average_precisions)))
def evaluate(self,
generator,
iou_threshold=0.3,
score_threshold=0.3,
max_detections=100,
save_path=None):
""" Evaluate a given dataset using a given model.
code originally from https://github.com/fizyr/keras-retinanet
# Arguments
generator : The generator that represents the dataset to evaluate.
model : The model to evaluate.
iou_threshold : The threshold used to consider when a detection is positive or negative.
score_threshold : The score confidence threshold to use for detections.
max_detections : The maximum number of detections to use per image.
save_path : The path to save images with visualized detections to.
# Returns
A dict mapping class names to mAP scores.
"""
# gather all detections and annotations
all_detections = [[None for i in range(generator.num_classes())] for j in range(generator.size())]
all_annotations = [[None for i in range(generator.num_classes())] for j in range(generator.size())]
for i in range(generator.size()):
raw_image = generator.load_image(i)
raw_height, raw_width, raw_channels = raw_image.shape
# make the boxes and the labels
pred_boxes = self.predict(raw_image)
score = np.array([box.score for box in pred_boxes])
pred_labels = np.array([box.label for box in pred_boxes])
if len(pred_boxes) > 0:
pred_boxes = np.array([[box.xmin*raw_width, box.ymin*raw_height, box.xmax*raw_width, box.ymax*raw_height, box.score] for box in pred_boxes])
else:
pred_boxes = np.array([[]])
# sort the boxes and the labels according to scores
score_sort = np.argsort(-score)
pred_labels = pred_labels[score_sort]
pred_boxes = pred_boxes[score_sort]
# copy detections to all_detections
for label in range(generator.num_classes()):
all_detections[i][label] = pred_boxes[pred_labels == label, :]
annotations = generator.load_annotation(i)
# copy detections to all_annotations
for label in range(generator.num_classes()):
all_annotations[i][label] = annotations[annotations[:, 4] == label, :4].copy()
# compute mAP by comparing all detections and all annotations
average_precisions = {}
for label in range(generator.num_classes()):
false_positives = np.zeros((0,))
true_positives = np.zeros((0,))
scores = np.zeros((0,))
num_annotations = 0.0
for i in range(generator.size()):
detections = all_detections[i][label]
annotations = all_annotations[i][label]
num_annotations += annotations.shape[0]
detected_annotations = []
for d in detections:
scores = np.append(scores, d[4])
if annotations.shape[0] == 0:
false_positives = np.append(false_positives, 1)
true_positives = np.append(true_positives, 0)
continue
overlaps = compute_overlap(np.expand_dims(d, axis=0), annotations)
assigned_annotation = np.argmax(overlaps, axis=1)
max_overlap = overlaps[0, assigned_annotation]
if max_overlap >= iou_threshold and assigned_annotation not in detected_annotations:
false_positives = np.append(false_positives, 0)
true_positives = np.append(true_positives, 1)
detected_annotations.append(assigned_annotation)
else:
false_positives = np.append(false_positives, 1)
true_positives = np.append(true_positives, 0)
# no annotations -> AP for this class is 0 (is this correct?)
if num_annotations == 0:
average_precisions[label] = 0
continue
# sort by score
indices = np.argsort(-scores)
false_positives = false_positives[indices]
true_positives = true_positives[indices]
# compute false positives and true positives
false_positives = np.cumsum(false_positives)
true_positives = np.cumsum(true_positives)
# compute recall and precision
recall = true_positives / num_annotations
precision = true_positives / np.maximum(true_positives + false_positives, np.finfo(np.float64).eps)
# compute average precision
average_precision = compute_ap(recall, precision)
average_precisions[label] = average_precision
return average_precisions
def predict(self, image):
image_h, image_w, _ = image.shape
image = cv2.resize(image, (self.input_size, self.input_size))
image = self.feature_extractor.normalize(image)
input_image = image[:,:,::-1]
input_image = np.expand_dims(input_image, 0)
dummy_array = np.zeros((1,1,1,1,self.max_box_per_image,4))
netout = self.model.predict([input_image, dummy_array])[0]
boxes = decode_netout(netout, self.anchors, self.nb_class)
return boxes