const URL_REG_EXP = /https?:\/\/(www\.)?[-a-zA-Z0-9@:%._+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_+.~#?&/=]*)/gi;
const extractLinkFromText = (text: string): string | null => {
  const urls: string[] | null = text.match(URL_REG_EXP);
  if (!urls || !urls.length) {
    return null;
  }
  return urls[0];
};

git clone --depth 1 https://github.com/tensorflow/models

Cloning into 'models'...
remote: Enumerating objects: 2301, done.
remote: Counting objects: 100% (2301/2301), done.
remote: Compressing objects: 100% (2000/2000), done.
remote: Total 2301 (delta 561), reused 922 (delta 278), pack-reused 0
Receiving objects: 100% (2301/2301), 30.60 MiB | 13.90 MiB/s, done.
Resolving deltas: 100% (561/561), done.

cd ./models/research
protoc object_detection/protos/*.proto --python_out=.

cp ./object_detection/packages/tf2/setup.py .
pip install . --quiet

python object_detection/builders/model_builder_tf2_test.py

[       OK ] ModelBuilderTF2Test.test_unknown_ssd_feature_extractor
----------------------------------------------------------------------
Ran 20 tests in 45.072s
OK (skipped=1)

import tensorflow as tf
import pathlib
MODEL_NAME = 'ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8'
TF_MODELS_BASE_PATH = 'http://download.tensorflow.org/models/object_detection/tf2/20200711/'
CACHE_FOLDER = './cache'
def download_tf_model(model_name, cache_folder):
    model_url = TF_MODELS_BASE_PATH + model_name + '.tar.gz'
    model_dir = tf.keras.utils.get_file(
        fname=model_name,
        origin=model_url,
        untar=True,
        cache_dir=pathlib.Path(cache_folder).absolute()
    )
    return model_dir
# Start the model download.
model_dir = download_tf_model(MODEL_NAME, CACHE_FOLDER)
print(model_dir)

/content/cache/datasets/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8

import os
# Import Object Detection API helpers.
from object_detection.utils import label_map_util
# Loads the COCO labels data (class names and indices relations).
def load_coco_labels():
    # Object Detection API already has a complete set of COCO classes defined for us.
    label_map_path = os.path.join(
        'models/research/object_detection/data',
        'mscoco_complete_label_map.pbtxt'
    )
    label_map = label_map_util.load_labelmap(label_map_path)
    # Class ID to Class Name mapping.
    categories = label_map_util.convert_label_map_to_categories(
        label_map,
        max_num_classes=label_map_util.get_max_label_map_index(label_map),
        use_display_name=True
    )
    category_index = label_map_util.create_category_index(categories)
    # Class Name to Class ID mapping.
    label_map_dict = label_map_util.get_label_map_dict(label_map, use_display_name=True)
    return category_index, label_map_dict
# Load COCO labels.
coco_category_index, coco_label_map_dict = load_coco_labels()
print('coco_category_index:', coco_category_index)
print('coco_label_map_dict:', coco_label_map_dict)

coco_category_index:
{
    1: {'id': 1, 'name': 'person'},
    2: {'id': 2, 'name': 'bicycle'},
    ...
    90: {'id': 90, 'name': 'toothbrush'},
}
coco_label_map_dict:
{
    'background': 0,
    'person': 1,
    'bicycle': 2,
    'car': 3,
    ...
    'toothbrush': 90,
}

import tensorflow as tf
# Import Object Detection API helpers.
from object_detection.utils import config_util
from object_detection.builders import model_builder
# Generates the detection function for specific model and specific model's checkpoint
def detection_fn_from_checkpoint(config_path, checkpoint_path):
    # Build the model.
    pipeline_config = config_util.get_configs_from_pipeline_file(config_path)
    model_config = pipeline_config['model']
    model = model_builder.build(
        model_config=model_config,
        is_training=False,
    )
    # Restore checkpoints.
    ckpt = tf.compat.v2.train.Checkpoint(model=model)
    ckpt.restore(checkpoint_path).expect_partial()
    # This is a function that will do the detection.
    @tf.function
    def detect_fn(image):
        image, shapes = model.preprocess(image)
        prediction_dict = model.predict(image, shapes)
        detections = model.postprocess(prediction_dict, shapes)
        return detections, prediction_dict, tf.reshape(shapes, [-1])
    return detect_fn
inference_detect_fn = detection_fn_from_checkpoint(
    config_path=os.path.join('cache', 'datasets', MODEL_NAME, 'pipeline.config'),
    checkpoint_path=os.path.join('cache', 'datasets', MODEL_NAME, 'checkpoint', 'ckpt-0'),
)

import matplotlib.pyplot as plt
%matplotlib inline
# Creating a TensorFlow dataset of just one image.
inference_ds = tf.keras.preprocessing.image_dataset_from_directory(
  directory='inference',
  image_size=(640, 640),
  batch_size=1,
  shuffle=False,
  label_mode=None
)
# Numpy version of the dataset.
inference_ds_numpy = list(inference_ds.as_numpy_iterator())
# You may preview the images in dataset like this.
plt.figure(figsize=(14, 14))
for i, image in enumerate(inference_ds_numpy):
    plt.subplot(2, 2, i + 1)
    plt.imshow(image[0].astype("uint8"))
    plt.axis("off")
plt.show()

detections, predictions_dict, shapes = inference_detect_fn(
    inference_ds_numpy[0]
)

boxes = detections['detection_boxes'].numpy()
scores = detections['detection_scores'].numpy()
classes = detections['detection_classes'].numpy()
num_detections = detections['num_detections'].numpy()[0]
print('boxes.shape: ', boxes.shape)
print('scores.shape: ', scores.shape)
print('classes.shape: ', classes.shape)
print('num_detections:', num_detections)

boxes.shape:  (1, 100, 4)
scores.shape:  (1, 100)
classes.shape:  (1, 100)
num_detections: 100.0

print('First 5 boxes:')
print(boxes[0,:5])
print('First 5 scores:')
print(scores[0,:5])
print('First 5 classes:')
print(classes[0,:5])
class_names = [coco_category_index[idx + 1]['name'] for idx in classes[0]]
print('First 5 class names:')
print(class_names[:5])

First 5 boxes:
[[0.17576033 0.84654826 0.25642633 0.88327974]
[0.5187813  0.12410264 0.6344235  0.34545377]
[0.5220358  0.5181462  0.6329132  0.7669856 ]
[0.50933677 0.7045719  0.5619138  0.7446198 ]
[0.44761637 0.51942706 0.61237675 0.75963426]]
First 5 scores:
[0.6950246 0.6343004 0.591157  0.5827219 0.5415643]
First 5 classes:
[9. 8. 8. 0. 8.]
First 5 class names:
['traffic light', 'boat', 'boat', 'person', 'boat']

# Importing Object Detection API helpers.
from object_detection.utils import visualization_utils
# Visualizes the bounding boxes on top of the image.
def visualize_detections(image_np, detections, category_index):
    label_id_offset = 1
    image_np_with_detections = image_np.copy()
    visualization_utils.visualize_boxes_and_labels_on_image_array(
        image_np_with_detections,
        detections['detection_boxes'][0].numpy(),
        (detections['detection_classes'][0].numpy() + label_id_offset).astype(int),
        detections['detection_scores'][0].numpy(),
        category_index,
        use_normalized_coordinates=True,
        max_boxes_to_draw=200,
        min_score_thresh=.4,
        agnostic_mode=False,
    )
    plt.figure(figsize=(12, 16))
    plt.imshow(image_np_with_detections)
    plt.show()
# Visualizing the detections.
visualize_detections(
    image_np=tf.cast(inference_ds_numpy[0][0], dtype=tf.uint32).numpy(),
    detections=detections,
    category_index=coco_category_index,
)

import os
import math
import shutil
from pathlib import Path
from PIL import Image, ImageOps, ImageEnhance
# Resize an image.
def preprocess_resize(target_width):
    def preprocess(image: Image.Image, log) -> Image.Image:
        (width, height) = image.size
        ratio = width / height
        if width > target_width:
            target_height = math.floor(target_width / ratio)
            log(f'Resizing: To size {target_width}x{target_height}')
            image = image.resize((target_width, target_height))
        else:
            log('Resizing: Image already resized, skipping...')
        return image
    return preprocess
# Crop an image.
def preprocess_crop_square():
    def preprocess(image: Image.Image, log) -> Image.Image:
        (width, height) = image.size
        left = 0
        top = 0
        right = width
        bottom = height
        crop_size = min(width, height)
        if width >= height:
            # Horizontal image.
            log(f'Squre cropping: Horizontal {crop_size}x{crop_size}')
            left = width // 2 - crop_size // 2
            right = left + crop_size
        else:
            # Vetyical image.
            log(f'Squre cropping: Vertical {crop_size}x{crop_size}')
            top = height // 2 - crop_size // 2
            bottom = top + crop_size
        image = image.crop((left, top, right, bottom))
        return image
    return preprocess
# Apply exif transpose to an image.
def preprocess_exif_transpose():
    # @see: https://pillow.readthedocs.io/en/stable/reference/ImageOps.html
    def preprocess(image: Image.Image, log) -> Image.Image:
        log('EXif transpose')
        image = ImageOps.exif_transpose(image)
        return image
    return preprocess
# Apply color transformations to the image.
def preprocess_color(brightness, contrast, color, sharpness):
    # @see: https://pillow.readthedocs.io/en/3.0.x/reference/ImageEnhance.html
    def preprocess(image: Image.Image, log) -> Image.Image:
        log('Coloring')
        enhancer = ImageEnhance.Color(image)
        image = enhancer.enhance(color)
        enhancer = ImageEnhance.Brightness(image)
        image = enhancer.enhance(brightness)
        enhancer = ImageEnhance.Contrast(image)
        image = enhancer.enhance(contrast)
        enhancer = ImageEnhance.Sharpness(image)
        image = enhancer.enhance(sharpness)
        return image
    return preprocess
# Image pre-processing pipeline.
def preprocess_pipeline(src_dir, dest_dir, preprocessors=[], files_num_limit=0, override=False):
    # Create destination folder if not exists.
    Path(dest_dir).mkdir(parents=False, exist_ok=True)
    # Get the list of files to be copied.
    src_file_names = os.listdir(src_dir)
    files_total = files_num_limit if files_num_limit > 0 else len(src_file_names)
    files_processed = 0
    # Logger function.
    def preprocessor_log(message):
        print('  ' + message)
    # Iterate through files.
    for src_file_index, src_file_name in enumerate(src_file_names):
        if files_num_limit > 0 and src_file_index >= files_num_limit:
            break
        # Copy file.
        src_file_path = os.path.join(src_dir, src_file_name)
        dest_file_path = os.path.join(dest_dir, src_file_name)
        progress = math.floor(100 * (src_file_index + 1) / files_total)
        print(f'Image {src_file_index + 1}/{files_total} | {progress}% |  {src_file_path}')
        if not os.path.isfile(src_file_path):
            preprocessor_log('Source is not a file, skipping...\n')
            continue
        if not override and os.path.exists(dest_file_path):
            preprocessor_log('File already exists, skipping...\n')
            continue
        shutil.copy(src_file_path, dest_file_path)
        files_processed += 1
        # Preprocess file.
        image = Image.open(dest_file_path)
        for preprocessor in preprocessors:
            image = preprocessor(image, preprocessor_log)
        image.save(dest_file_path, quality=95)
        print('')
    print(f'{files_processed} out of {files_total} files have been processed')
# Launching the image preprocessing pipeline.
preprocess_pipeline(
    src_dir='dataset/printed_links/raw',
    dest_dir='dataset/printed_links/processed',
    override=True,
    # files_num_limit=1,
    preprocessors=[
        preprocess_exif_transpose(),
        preprocess_resize(target_width=1024),
        preprocess_crop_square(),
        preprocess_color(brightness=2, contrast=1.3, color=0, sharpness=1),
    ]
)

import matplotlib.pyplot as plt
import numpy as np
def preview_images(images_dir, images_num=1, figsize=(15, 15)):
    image_names = os.listdir(images_dir)
    image_names = image_names[:images_num]
    num_cells = math.ceil(math.sqrt(images_num))
    figure = plt.figure(figsize=figsize)
    for image_index, image_name in enumerate(image_names):
        image_path = os.path.join(images_dir, image_name)
        image = Image.open(image_path)
        figure.add_subplot(num_cells, num_cells, image_index + 1)
        plt.imshow(np.asarray(image))
    plt.show()
preview_images('dataset/printed_links/processed', images_num=4, figsize=(16, 16))

labelImg dataset/printed_links/processed

import re
import random
def partition_dataset(
    images_dir,
    xml_labels_dir,
    train_dir,
    test_dir,
    val_dir,
    train_ratio,
    test_ratio,
    val_ratio,
    copy_xml
):
    if not os.path.exists(train_dir):
        os.makedirs(train_dir)
    if not os.path.exists(test_dir):
        os.makedirs(test_dir)
    if not os.path.exists(val_dir):
        os.makedirs(val_dir)
    images = [f for f in os.listdir(images_dir)
              if re.search(r'([a-zA-Z0-9\s_\\.\-\(\):])+(.jpg|.jpeg|.png)$', f, re.IGNORECASE)]
    num_images = len(images)
    num_train_images = math.ceil(train_ratio * num_images)
    num_test_images = math.ceil(test_ratio * num_images)
    num_val_images = math.ceil(val_ratio * num_images)
    print('Intended split')
    print(f'  train: {num_train_images}/{num_images} images')
    print(f'  test: {num_test_images}/{num_images} images')
    print(f'  val: {num_val_images}/{num_images} images')
    actual_num_train_images = 0
    actual_num_test_images = 0
    actual_num_val_images = 0
    def copy_random_images(num_images, dest_dir):
        copied_num = 0
        if not num_images:
            return copied_num
        for i in range(num_images):
            if not len(images):
                break
            idx = random.randint(0, len(images)-1)
            filename = images[idx]
            shutil.copyfile(os.path.join(images_dir, filename), os.path.join(dest_dir, filename))
            if copy_xml:
                xml_filename = os.path.splitext(filename)[0]+'.xml'
                shutil.copyfile(os.path.join(xml_labels_dir, xml_filename), os.path.join(dest_dir, xml_filename))
            images.remove(images[idx])
            copied_num += 1
        return copied_num
    actual_num_train_images = copy_random_images(num_train_images, train_dir)
    actual_num_test_images = copy_random_images(num_test_images, test_dir)
    actual_num_val_images = copy_random_images(num_val_images, val_dir)
    print('\n', 'Actual split')
    print(f'  train: {actual_num_train_images}/{num_images} images')
    print(f'  test: {actual_num_test_images}/{num_images} images')
    print(f'  val: {actual_num_val_images}/{num_images} images')
partition_dataset(
    images_dir='dataset/printed_links/processed',
    train_dir='dataset/printed_links/partitioned/train',
    test_dir='dataset/printed_links/partitioned/test',
    val_dir='dataset/printed_links/partitioned/val',
    xml_labels_dir='dataset/printed_links/labels/xml',
    train_ratio=0.8,
    test_ratio=0.2,
    val_ratio=0,
    copy_xml=True
)

dataset/
└── printed_links
    ├── labels
    │   └── xml
    ├── partitioned
    │   ├── test
    │   └── train
    │       ├── IMG_9140.JPG
    │       ├── IMG_9140.xml
    │       ├── IMG_9141.JPG
    │       ├── IMG_9141.xml
    │       ...
    ├── processed
    └── raw

mkdir -p dataset/printed_links/labels/csv
mkdir -p dataset/printed_links/tfrecords

item {
  id: 1
  name: 'http'
}

import os
import io
import math
import glob
import tensorflow as tf
import pandas as pd
import xml.etree.ElementTree as ET
from PIL import Image
from collections import namedtuple
from object_detection.utils import dataset_util, label_map_util
tf1 = tf.compat.v1
# Convers labels from XML format to CSV.
def xml_to_csv(path):
    xml_list = []
    for xml_file in glob.glob(path + '/*.xml'):
        tree = ET.parse(xml_file)
        root = tree.getroot()
        for member in root.findall('object'):
            value = (root.find('filename').text,
                int(root.find('size')[0].text),
                int(root.find('size')[1].text),
                member[0].text,
                int(member[4][0].text),
                int(member[4][1].text),
                int(member[4][2].text),
                int(member[4][3].text)
            )
            xml_list.append(value)
    column_name = ['filename', 'width', 'height', 'class', 'xmin', 'ymin', 'xmax', 'ymax']
    xml_df = pd.DataFrame(xml_list, columns=column_name)
    return xml_df
def class_text_to_int(row_label, label_map_dict):
    return label_map_dict[row_label]
def split(df, group):
    data = namedtuple('data', ['filename', 'object'])
    gb = df.groupby(group)
    return [data(filename, gb.get_group(x)) for filename, x in zip(gb.groups.keys(), gb.groups)]
# Creates a TFRecord.
def create_tf_example(group, path, label_map_dict):
    with tf1.gfile.GFile(os.path.join(path, '{}'.format(group.filename)), 'rb') as fid:
        encoded_jpg = fid.read()
    encoded_jpg_io = io.BytesIO(encoded_jpg)
    image = Image.open(encoded_jpg_io)
    width, height = image.size
    filename = group.filename.encode('utf8')
    image_format = b'jpg'
    xmins = []
    xmaxs = []
    ymins = []
    ymaxs = []
    classes_text = []
    classes = []
    for index, row in group.object.iterrows():
        xmins.append(row['xmin'] / width)
        xmaxs.append(row['xmax'] / width)
        ymins.append(row['ymin'] / height)
        ymaxs.append(row['ymax'] / height)
        classes_text.append(row['class'].encode('utf8'))
        classes.append(class_text_to_int(row['class'], label_map_dict))
    tf_example = tf1.train.Example(features=tf1.train.Features(feature={
        'image/height': dataset_util.int64_feature(height),
        'image/width': dataset_util.int64_feature(width),
        'image/filename': dataset_util.bytes_feature(filename),
        'image/source_id': dataset_util.bytes_feature(filename),
        'image/encoded': dataset_util.bytes_feature(encoded_jpg),
        'image/format': dataset_util.bytes_feature(image_format),
        'image/object/bbox/xmin': dataset_util.float_list_feature(xmins),
        'image/object/bbox/xmax': dataset_util.float_list_feature(xmaxs),
        'image/object/bbox/ymin': dataset_util.float_list_feature(ymins),
        'image/object/bbox/ymax': dataset_util.float_list_feature(ymaxs),
        'image/object/class/text': dataset_util.bytes_list_feature(classes_text),
        'image/object/class/label': dataset_util.int64_list_feature(classes),
    }))
    return tf_example
def dataset_to_tfrecord(
    images_dir,
    xmls_dir,
    label_map_path,
    output_path,
    csv_path=None
):
    label_map = label_map_util.load_labelmap(label_map_path)
    label_map_dict = label_map_util.get_label_map_dict(label_map)
    tfrecord_writer = tf1.python_io.TFRecordWriter(output_path)
    images_path = os.path.join(images_dir)
    csv_examples = xml_to_csv(xmls_dir)
    grouped_examples = split(csv_examples, 'filename')
    for group in grouped_examples:
        tf_example = create_tf_example(group, images_path, label_map_dict)
        tfrecord_writer.write(tf_example.SerializeToString())
    tfrecord_writer.close()
    print('Successfully created the TFRecord file: {}'.format(output_path))
    if csv_path is not None:
        csv_examples.to_csv(csv_path, index=None)
        print('Successfully created the CSV file: {}'.format(csv_path))
# Generate a TFRecord for train dataset.
dataset_to_tfrecord(
    images_dir='dataset/printed_links/partitioned/train',
    xmls_dir='dataset/printed_links/partitioned/train',
    label_map_path='dataset/printed_links/labels/label_map.pbtxt',
    output_path='dataset/printed_links/tfrecords/train.record',
    csv_path='dataset/printed_links/labels/csv/train.csv'
)
# Generate a TFRecord for test dataset.
dataset_to_tfrecord(
    images_dir='dataset/printed_links/partitioned/test',
    xmls_dir='dataset/printed_links/partitioned/test',
    label_map_path='dataset/printed_links/labels/label_map.pbtxt',
    output_path='dataset/printed_links/tfrecords/test.record',
    csv_path='dataset/printed_links/labels/csv/test.csv'
)

dataset/
└── printed_links
    ├── labels
    │   ├── csv
    │   ├── label_map.pbtxt
    │   └── xml
    ├── partitioned
    │   ├── test
    │   ├── train
    │   └── val
    ├── processed
    ├── raw
    └── tfrecords
        ├── test.record
        └── train.record

import tensorflow as tf
# Count the number of examples in the dataset.
def count_tfrecords(tfrecords_filename):
    raw_dataset = tf.data.TFRecordDataset(tfrecords_filename)
    # Keep in mind that the list() operation might be
    # a performance bottleneck for large datasets.
    return len(list(raw_dataset))
TRAIN_RECORDS_NUM = count_tfrecords('dataset/printed_links/tfrecords/train.record')
TEST_RECORDS_NUM = count_tfrecords('dataset/printed_links/tfrecords/test.record')
print('TRAIN_RECORDS_NUM: ', TRAIN_RECORDS_NUM)
print('TEST_RECORDS_NUM:  ', TEST_RECORDS_NUM)

TRAIN_RECORDS_NUM:  100
TEST_RECORDS_NUM:   25

import tensorflow as tf
import numpy as np
from google.protobuf import text_format
import matplotlib.pyplot as plt
# Import Object Detection API.
from object_detection.utils import visualization_utils
from object_detection.protos import string_int_label_map_pb2
from object_detection.data_decoders.tf_example_decoder import TfExampleDecoder
%matplotlib inline
# Visualize the TFRecord dataset.
def visualize_tfrecords(tfrecords_filename, label_map=None, print_num=1):
    decoder = TfExampleDecoder(
        label_map_proto_file=label_map,
        use_display_name=False
    )
    if label_map is not None:
        label_map_proto = string_int_label_map_pb2.StringIntLabelMap()
        with tf.io.gfile.GFile(label_map,'r') as f:
            text_format.Merge(f.read(), label_map_proto)
            class_dict = {}
            for entry in label_map_proto.item:
                class_dict[entry.id] = {'name': entry.name}
    raw_dataset = tf.data.TFRecordDataset(tfrecords_filename)
    for raw_record in raw_dataset.take(print_num):
        example = decoder.decode(raw_record)
        image = example['image'].numpy()
        boxes = example['groundtruth_boxes'].numpy()
        confidences = example['groundtruth_image_confidences']
        filename = example['filename']
        area = example['groundtruth_area']
        classes = example['groundtruth_classes'].numpy()
        image_classes = example['groundtruth_image_classes']
        weights = example['groundtruth_weights']
        scores = np.ones(boxes.shape[0])
        visualization_utils.visualize_boxes_and_labels_on_image_array(
            image,
            boxes,
            classes,
            scores,
            class_dict,
            max_boxes_to_draw=None,
            use_normalized_coordinates=True
        )
        plt.figure(figsize=(8, 8))
        plt.imshow(image)
    plt.show()
# Visualizing the training TFRecord dataset.
visualize_tfrecords(
    tfrecords_filename='dataset/printed_links/tfrecords/train.record',
    label_map='dataset/printed_links/labels/label_map.pbtxt',
    print_num=3
)

mkdir -p logs

%load_ext tensorboard

%tensorboard --logdir ./logs

import tensorflow as tf
from shutil import copyfile
from google.protobuf import text_format
from object_detection.protos import pipeline_pb2
# Adjust pipeline config modification here if needed.
def modify_config(pipeline):
    # Model config.
    pipeline.model.ssd.num_classes = 1
    # Train config.
    pipeline.train_config.batch_size = 8
    pipeline.train_config.fine_tune_checkpoint = 'cache/datasets/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8/checkpoint/ckpt-0'
    pipeline.train_config.fine_tune_checkpoint_type = 'detection'
    # Train input reader config.
    pipeline.train_input_reader.label_map_path = 'dataset/printed_links/labels/label_map.pbtxt'
    pipeline.train_input_reader.tf_record_input_reader.input_path[0] = 'dataset/printed_links/tfrecords/train.record'
    # Eval input reader config.
    pipeline.eval_input_reader[0].label_map_path = 'dataset/printed_links/labels/label_map.pbtxt'
    pipeline.eval_input_reader[0].tf_record_input_reader.input_path[0] = 'dataset/printed_links/tfrecords/test.record'
    return pipeline
def clone_pipeline_config():
    copyfile(
        'cache/datasets/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8/pipeline.config',
        'pipeline.config'
    )
def setup_pipeline(pipeline_config_path):
    clone_pipeline_config()
    pipeline = read_pipeline_config(pipeline_config_path)
    pipeline = modify_config(pipeline)
    write_pipeline_config(pipeline_config_path, pipeline)
    return pipeline
def read_pipeline_config(pipeline_config_path):
    pipeline = pipeline_pb2.TrainEvalPipelineConfig()
    with tf.io.gfile.GFile(pipeline_config_path, "r") as f:
        proto_str = f.read()
        text_format.Merge(proto_str, pipeline)
    return pipeline
def write_pipeline_config(pipeline_config_path, pipeline):
    config_text = text_format.MessageToString(pipeline)
    with tf.io.gfile.GFile(pipeline_config_path, "wb") as f:
        f.write(config_text)
# Adjusting the pipeline configuration.
pipeline = setup_pipeline('pipeline.config')
print(pipeline)

model {
  ssd {
    num_classes: 1
    image_resizer {
      fixed_shape_resizer {
        height: 640
        width: 640
      }
    }
    feature_extractor {
      type: "ssd_mobilenet_v2_fpn_keras"
      depth_multiplier: 1.0
      min_depth: 16
      conv_hyperparams {
        regularizer {
          l2_regularizer {
            weight: 3.9999998989515007e-05
          }
        }
        initializer {
          random_normal_initializer {
            mean: 0.0
            stddev: 0.009999999776482582
          }
        }
        activation: RELU_6
        batch_norm {
          decay: 0.996999979019165
          scale: true
          epsilon: 0.0010000000474974513
        }
      }
      use_depthwise: true
      override_base_feature_extractor_hyperparams: true
      fpn {
        min_level: 3
        max_level: 7
        additional_layer_depth: 128
      }
    }
    box_coder {
      faster_rcnn_box_coder {
        y_scale: 10.0
        x_scale: 10.0
        height_scale: 5.0
        width_scale: 5.0
      }
    }
    matcher {
      argmax_matcher {
        matched_threshold: 0.5
        unmatched_threshold: 0.5
        ignore_thresholds: false
        negatives_lower_than_unmatched: true
        force_match_for_each_row: true
        use_matmul_gather: true
      }
    }
    similarity_calculator {
      iou_similarity {
      }
    }
    box_predictor {
      weight_shared_convolutional_box_predictor {
        conv_hyperparams {
          regularizer {
            l2_regularizer {
              weight: 3.9999998989515007e-05
            }
          }
          initializer {
            random_normal_initializer {
              mean: 0.0
              stddev: 0.009999999776482582
            }
          }
          activation: RELU_6
          batch_norm {
            decay: 0.996999979019165
            scale: true
            epsilon: 0.0010000000474974513
          }
        }
        depth: 128
        num_layers_before_predictor: 4
        kernel_size: 3
        class_prediction_bias_init: -4.599999904632568
        share_prediction_tower: true
        use_depthwise: true
      }
    }
    anchor_generator {
      multiscale_anchor_generator {
        min_level: 3
        max_level: 7
        anchor_scale: 4.0
        aspect_ratios: 1.0
        aspect_ratios: 2.0
        aspect_ratios: 0.5
        scales_per_octave: 2
      }
    }
    post_processing {
      batch_non_max_suppression {
        score_threshold: 9.99999993922529e-09
        iou_threshold: 0.6000000238418579
        max_detections_per_class: 100
        max_total_detections: 100
        use_static_shapes: false
      }
      score_converter: SIGMOID
    }
    normalize_loss_by_num_matches: true
    loss {
      localization_loss {
        weighted_smooth_l1 {
        }
      }
      classification_loss {
        weighted_sigmoid_focal {
          gamma: 2.0
          alpha: 0.25
        }
      }
      classification_weight: 1.0
      localization_weight: 1.0
    }
    encode_background_as_zeros: true
    normalize_loc_loss_by_codesize: true
    inplace_batchnorm_update: true
    freeze_batchnorm: false
  }
}
train_config {
  batch_size: 8
  data_augmentation_options {
    random_horizontal_flip {
    }
  }
  data_augmentation_options {
    random_crop_image {
      min_object_covered: 0.0
      min_aspect_ratio: 0.75
      max_aspect_ratio: 3.0
      min_area: 0.75
      max_area: 1.0
      overlap_thresh: 0.0
    }
  }
  sync_replicas: true
  optimizer {
    momentum_optimizer {
      learning_rate {
        cosine_decay_learning_rate {
          learning_rate_base: 0.07999999821186066
          total_steps: 50000
          warmup_learning_rate: 0.026666000485420227
          warmup_steps: 1000
        }
      }
      momentum_optimizer_value: 0.8999999761581421
    }
    use_moving_average: false
  }
  fine_tune_checkpoint: "cache/datasets/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8/checkpoint/ckpt-0"
  num_steps: 50000
  startup_delay_steps: 0.0
  replicas_to_aggregate: 8
  max_number_of_boxes: 100
  unpad_groundtruth_tensors: false
  fine_tune_checkpoint_type: "detection"
  fine_tune_checkpoint_version: V2
}
train_input_reader {
  label_map_path: "dataset/printed_links/labels/label_map.pbtxt"
  tf_record_input_reader {
    input_path: "dataset/printed_links/tfrecords/train.record"
  }
}
eval_config {
  metrics_set: "coco_detection_metrics"
  use_moving_averages: false
}
eval_input_reader {
  label_map_path: "dataset/printed_links/labels/label_map.pbtxt"
  shuffle: false
  num_epochs: 1
  tf_record_input_reader {
    input_path: "dataset/printed_links/tfrecords/test.record"
  }
}

%%bash
NUM_TRAIN_STEPS=1000
CHECKPOINT_EVERY_N=1000
PIPELINE_CONFIG_PATH=pipeline.config
MODEL_DIR=./logs
SAMPLE_1_OF_N_EVAL_EXAMPLES=1
python ./models/research/object_detection/model_main_tf2.py \
  --model_dir=$MODEL_DIR \
  --num_train_steps=$NUM_TRAIN_STEPS \
  --sample_1_of_n_eval_examples=$SAMPLE_1_OF_N_EVAL_EXAMPLES \
  --pipeline_config_path=$PIPELINE_CONFIG_PATH \
  --checkpoint_every_n=$CHECKPOINT_EVERY_N \
  --alsologtostderr

logs
├── checkpoint
├── ckpt-1.data-00000-of-00001
├── ckpt-1.index
└── train
    └── events.out.tfevents.1606560330.b314c371fa10.1747.1628.v2

%%bash
PIPELINE_CONFIG_PATH=pipeline.config
MODEL_DIR=logs
python ./models/research/object_detection/model_main_tf2.py \
  --model_dir=$MODEL_DIR \
  --pipeline_config_path=$PIPELINE_CONFIG_PATH \
  --checkpoint_dir=$MODEL_DIR \

%%bash
python ./models/research/object_detection/exporter_main_v2.py \
    --input_type=image_tensor \
    --pipeline_config_path=pipeline.config \
    --trained_checkpoint_dir=logs \
    --output_directory=exported/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8

exported
└── ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8
    ├── checkpoint
    │   ├── checkpoint
    │   ├── ckpt-0.data-00000-of-00001
    │   └── ckpt-0.index
    ├── pipeline.config
    └── saved_model
        ├── assets
        ├── saved_model.pb
        └── variables
            ├── variables.data-00000-of-00001
            └── variables.index

import time
import math
PATH_TO_SAVED_MODEL = 'exported/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8/saved_model'
def detection_function_from_saved_model(saved_model_path):
    print('Loading saved model...', end='')
    start_time = time.time()
    # Load saved model and build the detection function
    detect_fn = tf.saved_model.load(saved_model_path)
    end_time = time.time()
    elapsed_time = end_time - start_time
    print('Done! Took {} seconds'.format(math.ceil(elapsed_time)))
    return detect_fn
exported_detect_fn = detection_function_from_saved_model(
    PATH_TO_SAVED_MODEL
)

Loading saved model...Done! Took 9 seconds

from object_detection.utils import label_map_util
category_index = label_map_util.create_category_index_from_labelmap(
    'dataset/printed_links/labels/label_map.pbtxt',
    use_display_name=True
)
print(category_index)

{1: {'id': 1, 'name': 'http'}}

import matplotlib.pyplot as plt
import tensorflow as tf
import numpy as np
from object_detection.utils import visualization_utils
from object_detection.data_decoders.tf_example_decoder import TfExampleDecoder
%matplotlib inline
def tensors_from_tfrecord(
    tfrecords_filename,
    tfrecords_num,
    dtype=tf.float32
):
    decoder = TfExampleDecoder()
    raw_dataset = tf.data.TFRecordDataset(tfrecords_filename)
    images = []
    for raw_record in raw_dataset.take(tfrecords_num):
        example = decoder.decode(raw_record)
        image = example['image']
        image = tf.cast(image, dtype=dtype)
        images.append(image)
    return images
def test_detection(tfrecords_filename, tfrecords_num, detect_fn):
    image_tensors = tensors_from_tfrecord(
        tfrecords_filename,
        tfrecords_num,
        dtype=tf.uint8
    )
    for image_tensor in image_tensors:
        image_np = image_tensor.numpy()
        # The model expects a batch of images, so add an axis with `tf.newaxis`.
        input_tensor = tf.expand_dims(image_tensor, 0)
        detections = detect_fn(input_tensor)
        # All outputs are batches tensors.
        # Convert to numpy arrays, and take index [0] to remove the batch dimension.
        # We're only interested in the first num_detections.
        num_detections = int(detections.pop('num_detections'))
        detections = {key: value[0, :num_detections].numpy() for key, value in detections.items()}
        detections['num_detections'] = num_detections
        # detection_classes should be ints.
        detections['detection_classes'] = detections['detection_classes'].astype(np.int64)
        image_np_with_detections = image_np.astype(int).copy()
        visualization_utils.visualize_boxes_and_labels_on_image_array(
            image_np_with_detections,
            detections['detection_boxes'],
            detections['detection_classes'],
            detections['detection_scores'],
            category_index,
            use_normalized_coordinates=True,
            max_boxes_to_draw=100,
            min_score_thresh=.3,
            agnostic_mode=False
        )
        plt.figure(figsize=(8, 8))
        plt.imshow(image_np_with_detections)
    plt.show()
test_detection(
    tfrecords_filename='dataset/printed_links/tfrecords/test.record',
    tfrecords_num=10,
    detect_fn=exported_detect_fn
)

pip install tensorflowjs --quiet

%%bash
tensorflowjs_converter \
    --input_format=tf_saved_model \
    --output_format=tfjs_graph_model \
    exported/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8/saved_model \
    exported_web/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8

exported_web
└── ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8
    ├── group1-shard1of4.bin
    ├── group1-shard2of4.bin
    ├── group1-shard3of4.bin
    ├── group1-shard4of4.bin
    └── model.json

import pathlib
def get_folder_size(folder_path):
    mB = 1000000
    root_dir = pathlib.Path(folder_path)
    sizeBytes = sum(f.stat().st_size for f in root_dir.glob('**/*') if f.is_file())
    return f'{sizeBytes//mB} MB'
print(f'Original model size:      {get_folder_size("cache/datasets/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8")}')
print(f'Exported model size:      {get_folder_size("exported/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8")}')
print(f'Exported WEB model size:  {get_folder_size("exported_web/ssd_mobilenet_v2_fpnlite_640x640_coco17_tpu-8")}')

Original model size:      31 MB
Exported model size:      28 MB
Exported WEB model size:  13 MB

import * as tf from '@tensorflow/tfjs';
const model = await tf.loadGraphModel(modelURL);