深度学习 卷积神经网络 第四课第三周 Autonomous driving application - Car detection - v1

本文介绍如何使用YOLOv2模型进行目标检测,包括关键步骤如置信度阈值筛选、非极大值抑制等,并展示了从模型加载到图像处理直至目标框绘制的完整流程。

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import os
os.environ['TF_CPP_MIN_LOG_LEVEL']='2'

import argparse
import matplotlib.pyplot as plt
from matplotlib.pyplot import imshow
import scipy.io
import scipy.misc
import numpy as np
import pandas as pd
import PIL
import tensorflow as tf
from keras import backend as K
from keras.layers import Input, Lambda, Conv2D
from keras.models import load_model, Model
from yolo_utils import read_classes, read_anchors, generate_colors, preprocess_image, draw_boxes, scale_boxes
from yad2k.models.keras_yolo import yolo_head, yolo_boxes_to_corners, preprocess_true_boxes, yolo_loss, yolo_body
def yolo_filter_boxes(box_confidence,boxes,box_class_probs,threshold= .6):
    box_scores=box_confidence*box_class_probs
    box_classes=K.argmax(box_scores,axis=-1)
    box_class_scores=K.max(box_scores,axis=-1)
    filtering_mask=box_class_scores>=threshold
    scores=tf.boolean_mask(box_class_scores,filtering_mask)
    boxes=tf.boolean_mask(boxes,filtering_mask)
    classes=tf.boolean_mask(box_classes,filtering_mask)
    return scores,boxes,classes
# with tf.Session() as test_a:
#     box_confidence = tf.random_normal([19, 19, 5, 1], mean=1, stddev=4, seed = 1)
#     boxes = tf.random_normal([19, 19, 5, 4], mean=1, stddev=4, seed = 1)
#     box_class_probs = tf.random_normal([19, 19, 5, 80], mean=1, stddev=4, seed = 1)
#     scores, boxes, classes = yolo_filter_boxes(box_confidence, boxes, box_class_probs, threshold = 0.5)
#     print("scores[2] = " + str(scores[2].eval()))
#     print("boxes[2] = " + str(boxes[2].eval()))
#     print("classes[2] = " + str(classes[2].eval()))
#     print("scores.shape = " + str(scores.shape))
#     print("boxes.shape = " + str(boxes.shape))
#     print("classes.shape = " + str(classes.shape))
def iou(box1,box2):
    xi1=max(box1[0],box2[0])
    yi1=max(box1[1],box2[1])
    xi2=min(box1[2],box2[2])
    yi2=min(box1[3],box2[3])
    inter_area=(yi2-yi1)*(xi2-xi1)
    box1_area=(box1[3]-box1[1])*(box1[2]-box1[0])
    box2_area=(box2[3]-box2[1])*(box2[2]-box2[0])
    union_area=box1_area+box2_area-inter_area
    iou=inter_area/union_area
    return iou
# box1 = (2, 1, 4, 3)
# box2 = (1, 2, 3, 4)
# print("iou = " + str(iou(box1, box2)))
def yolo_non_max_suppression(scores,boxes,classes,max_boxes=10,iou_threshold=0.5):
    max_boxes_tensor=K.variable(max_boxes,dtype="int32")
    K.get_session().run(tf.variables_initializer([max_boxes_tensor]))
    nms_indices=tf.image.non_max_suppression(boxes,scores,max_boxes,iou_threshold)
    scores=K.gather(scores,nms_indices)
    boxes=K.gather(boxes,nms_indices)
    classes=K.gather(classes,nms_indices)
    return scores,boxes,classes
# with tf.Session() as test_b:
#     scores = tf.random_normal([54,], mean=1, stddev=4, seed = 1)
#     boxes = tf.random_normal([54, 4], mean=1, stddev=4, seed = 1)
#     classes = tf.random_normal([54,], mean=1, stddev=4, seed = 1)
#     scores, boxes, classes = yolo_non_max_suppression(scores, boxes, classes)
#     print("scores[2] = " + str(scores[2].eval()))
#     print("boxes[2] = " + str(boxes[2].eval()))
#     print("classes[2] = " + str(classes[2].eval()))
#     print("scores.shape = " + str(scores.eval().shape))
#     print("boxes.shape = " + str(boxes.eval().shape))
#     print("classes.shape = " + str(classes.eval().shape))
def yolo_eval(yolo_outputs,image_shape=(720.,1280.),max_boxes=10,score_threshold=.6,iou_threshold=.5):
    box_confidence,box_xy,box_wh,box_class_prob=yolo_outputs[:]
    boxes=yolo_boxes_to_corners(box_xy,box_wh)
    scores,boxes,classes=yolo_filter_boxes(box_confidence,boxes,box_class_prob,score_threshold)
    boxes=scale_boxes(boxes,image_shape)
    scores,boxes,classes=yolo_non_max_suppression(scores,boxes,classes,max_boxes,iou_threshold)
    return scores,boxes,classes
# with tf.Session() as test_b:
#     yolo_outputs = (tf.random_normal([19, 19, 5, 1], mean=1, stddev=4, seed = 1),
#                     tf.random_normal([19, 19, 5, 2], mean=1, stddev=4, seed = 1),
#                     tf.random_normal([19, 19, 5, 2], mean=1, stddev=4, seed = 1),
#                     tf.random_normal([19, 19, 5, 80], mean=1, stddev=4, seed = 1))
#     scores, boxes, classes = yolo_eval(yolo_outputs)
#     print("scores[2] = " + str(scores[2].eval()))
#     print("boxes[2] = " + str(boxes[2].eval()))
#     print("classes[2] = " + str(classes[2].eval()))
#     print("scores.shape = " + str(scores.eval().shape))
#     print("boxes.shape = " + str(boxes.eval().shape))
#     print("classes.shape = " + str(classes.eval().shape))
sess=K.get_session()
class_names = read_classes("model_data/coco_classes.txt")
anchors = read_anchors("model_data/yolo_anchors.txt")
image_shape = (720., 1280.)
yolo_model=load_model("model_data/yolo.h5")
yolo_model.summary()
yolo_outputs = yolo_head(yolo_model.output, anchors, len(class_names))
scores, boxes, classes = yolo_eval(yolo_outputs, image_shape)
def predict(sess,image_file):
    image,image_data=preprocess_image("images/"+image_file,model_image_size=(608,608))
    out_scores,out_boxes,out_classes=sess.run([scores,boxes,classes],feed_dict={yolo_model.input:image_data,K.learning_phase():0})
    print('Found {} boxes for {}'.format(len(out_boxes),image_file))
    colors=generate_colors(class_names)
    draw_boxes(image,out_scores,out_boxes,out_classes,class_names,colors)
    image.save(os.path.join("out",image_file),quality=90)
    output_image=scipy.misc.imread(os.path.join("out",image_file))
    imshow(output_image)
    plt.show()
    return out_scores,out_boxes,out_classes
out_scores, out_boxes, out_classes = predict(sess, "0018.jpg")

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