Object_detection_image.py

######## Image Object Detection Using Tensorflow-trained Classifier #########
#
# Author: Evan Juras
# Date: 1/15/18
# Description: 
# This program uses a TensorFlow-trained classifier to perform object detection.
# It loads the classifier uses it to perform object detection on an image.
# It draws boxes and scores around the objects of interest in the image.

## Some of the code is copied from Google's example at
## https://github.com/tensorflow/models/blob/master/research/object_detection/object_detection_tutorial.ipynb

## and some is copied from Dat Tran's example at
## https://github.com/datitran/object_detector_app/blob/master/object_detection_app.py

## but I changed it to make it more understandable to me.

# Import packages
import os
import cv2
import numpy as np
import tensorflow as tf
import sys

# This is needed since the notebook is stored in the object_detection folder.
sys.path.append("..")

# Import utilites
from utils import label_map_util
from utils import visualization_utils as vis_util

# Define a function to process all images at once.
def object_detection_image(IMAGE_NAME):

    # Name of the directory containing the object detection module we're using
    MODEL_NAME = 'inference_graph'
    #IMAGE_NAME = '21.jpg'

    # Grab path to current working directory
    CWD_PATH = os.getcwd()

    # Path to frozen detection graph .pb file, which contains the model that is used
    # for object detection.
    PATH_TO_CKPT = os.path.join(CWD_PATH,MODEL_NAME,'frozen_inference_graph.pb')

    # Path to label map file
    PATH_TO_LABELS = os.path.join(CWD_PATH,'training','labelmap.pbtxt')

    # Path to image
    PATH_TO_IMAGE = os.path.join(CWD_PATH,'images/test/',IMAGE_NAME)

    # Number of classes the object detector can identify
    NUM_CLASSES = 2

    # Load the label map.
    # Label maps map indices to category names, so that when our convolution
    # network predicts `5`, we know that this corresponds to `king`.
    # Here we use internal utility functions, but anything that returns a
    # dictionary mapping integers to appropriate string labels would be fine
    label_map = label_map_util.load_labelmap(PATH_TO_LABELS)
    categories = label_map_util.convert_label_map_to_categories(label_map, max_num_classes=NUM_CLASSES, use_display_name=True)
    category_index = label_map_util.create_category_index(categories)

    # Load the Tensorflow model into memory.
    detection_graph = tf.Graph()
    with detection_graph.as_default():
        od_graph_def = tf.GraphDef()
        with tf.gfile.GFile(PATH_TO_CKPT, 'rb') as fid:
            serialized_graph = fid.read()
            od_graph_def.ParseFromString(serialized_graph)
            tf.import_graph_def(od_graph_def, name='')

        sess = tf.Session(graph=detection_graph)

    # Define input and output tensors (i.e. data) for the object detection classifier

    # Input tensor is the image
    image_tensor = detection_graph.get_tensor_by_name('image_tensor:0')

    # Output tensors are the detection boxes, scores, and classes
    # Each box represents a part of the image where a particular object was detected
    detection_boxes = detection_graph.get_tensor_by_name('detection_boxes:0')

    # Each score represents level of confidence for each of the objects.
    # The score is shown on the result image, together with the class label.
    detection_scores = detection_graph.get_tensor_by_name('detection_scores:0')
    detection_classes = detection_graph.get_tensor_by_name('detection_classes:0')

    # Number of objects detected
    num_detections = detection_graph.get_tensor_by_name('num_detections:0')

    # Load image using OpenCV and
    # expand image dimensions to have shape: [1, None, None, 3]
    # i.e. a single-column array, where each item in the column has the pixel RGB value    
    image = cv2.imread(PATH_TO_IMAGE)
    image_expanded = np.expand_dims(image, axis=0)
    
    # Perform the actual detection by running the model with the image as input
    (boxes, scores, classes, num) = sess.run(
        [detection_boxes, detection_scores, detection_classes, num_detections],
        feed_dict={image_tensor: image_expanded})


    # Draw the results of the detection (aka 'visulaize the results')

    vis_util.visualize_boxes_and_labels_on_image_array(
        image,
        IMAGE_NAME.split(".")[0] + ".txt", # 2020.02.21 joy
        np.squeeze(boxes),
        np.squeeze(classes).astype(np.int32),
        np.squeeze(scores),
        category_index,
        use_normalized_coordinates=True,
        line_thickness=8,
        min_score_thresh=0.60)

    # All the results have been drawn on image. Now display the image.
    cv2.imwrite(os.path.join(r'C:\\Users\\joy_lin\\models\\research\\object_detection\\PASCALVOC\\processed_img', IMAGE_NAME), image) # 2020.02.21 joy
    #cv2.imshow('Object detector', image)
    #
    ## Press any key to close the image
    #cv2.waitKey(0)
    #
    ## Clean up
    #cv2.destroyAllWindows()