TensorFlow Object Detection API,使用图像裁剪作为训练数据集



我想从Tensorflow Object Detection API训练一个ssd-inception-v2模型。我想使用的训练数据集是一堆不同大小的裁剪图像,没有边界框,因为裁剪本身就是边界框。

我按照create_pascal_tf_record.py示例相应地替换了边界框和分类部分,以生成 TFRecord,如下所示:

def dict_to_tf_example(imagepath, label):
image = Image.open(imagepath)
if image.format != 'JPEG':
print("Skipping file: " + imagepath)
return
img = np.array(image)
with tf.gfile.GFile(imagepath, 'rb') as fid:
encoded_jpg = fid.read()
# The reason to store image sizes was demonstrated
# in the previous example -- we have to know sizes
# of images to later read raw serialized string,
# convert to 1d array and convert to respective
# shape that image used to have.
height = img.shape[0]
width = img.shape[1]
key = hashlib.sha256(encoded_jpg).hexdigest()
# Put in the original images into array
# Just for future check for correctness
xmin = [5.0/100.0]
ymin = [5.0/100.0]
xmax = [95.0/100.0]
ymax = [95.0/100.0]
class_text = [label['name'].encode('utf8')]
classes = [label['id']]
example = tf.train.Example(features=tf.train.Features(feature={
'image/height':dataset_util.int64_feature(height),
'image/width': dataset_util.int64_feature(width),
'image/filename': dataset_util.bytes_feature(imagepath.encode('utf8')),
'image/source_id': dataset_util.bytes_feature(imagepath.encode('utf8')),
'image/encoded': dataset_util.bytes_feature(encoded_jpg),
'image/key/sha256': dataset_util.bytes_feature(key.encode('utf8')),
'image/format': dataset_util.bytes_feature('jpeg'.encode('utf8')),        
'image/object/class/text': dataset_util.bytes_list_feature(class_text),
'image/object/class/label': dataset_util.int64_list_feature(classes),
'image/object/bbox/xmin': dataset_util.float_list_feature(xmin),
'image/object/bbox/xmax': dataset_util.float_list_feature(xmax),
'image/object/bbox/ymin': dataset_util.float_list_feature(ymin),
'image/object/bbox/ymax': dataset_util.float_list_feature(ymax)
}))
return example

def main(_):
data_dir = FLAGS.data_dir
output_path = os.path.join(data_dir,FLAGS.output_path + '.record')
writer = tf.python_io.TFRecordWriter(output_path)
label_map = label_map_util.load_labelmap(FLAGS.label_map_path)
categories = label_map_util.convert_label_map_to_categories(label_map, max_num_classes=80, use_display_name=True)
category_index = label_map_util.create_category_index(categories)
category_list = os.listdir(data_dir)
gen = (category for category in categories if category['name'] in category_list)
for category in gen:
examples_path = os.path.join(data_dir,category['name'])
examples_list = os.listdir(examples_path)
for example in examples_list:
imagepath = os.path.join(examples_path,example)
tf_example = dict_to_tf_example(imagepath,category)
writer.write(tf_example.SerializeToString())
#       print(tf_example)
writer.close()

边界框是包含整个图像的硬编码。标签根据其相应的目录给出。我正在使用 mscoco_label_map.pbxt 进行标记,使用 ssd_inception_v2_pets.config 作为我的管道的基础。

我训练并冻结了模型以与 jupyter 笔记本示例一起使用。但是,最终结果是围绕整个图像的单个框。知道出了什么问题吗?

对象检测算法/网络通常通过预测边界框的位置以及类来工作。因此,训练数据通常需要包含边界框数据。通过向模型提供训练数据,并带有始终为图像大小的边界框,然后您可能会得到垃圾预测,包括一个始终勾勒图像轮廓的框。

这听起来像是训练数据的问题。您不应该提供裁剪的图像,而应该提供带有对象注释的完整图像/场景。此时,您基本上是在训练分类器。

尝试使用未裁剪的正确风格的图像进行训练,看看您如何进行。

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