YOLOv8 segment介绍

1.YOLOv8图像分割支持的数据格式：

(1).用于训练YOLOv8分割模型的数据集标签格式如下:

1).每幅图像对应一个文本文件：数据集中的每幅图像都有一个与图像文件同名的对应文本文件，扩展名为".txt";

2).文本文件中每个目标(object)占一行：文本文件中的每一行对应图像中的一个目标实例；

3).每行目标信息：如下所示：之间用空格分隔

A.目标类别索引：整数，例如：0代表person，1代表car，等等;

B.目标边界坐标：mask区域周围的边界坐标，归一化为[0, 1];

<class-index> <x1> <y1> <x2> <y2> ... <xn> <yn>

注：每行的长度不必相等；每个分隔label必须至少有3对xy点

(2).数据集YAML格式：Ultralytics框架使用YAML文件格式来定义用于训练分隔模型的数据集和模型配置，如下面测试数据集melon中melon_seg.yaml内容如下：在网上下载了60多幅包含西瓜和冬瓜的图像组成melon数据集

path: ../datasets/melon_seg # dataset root dir
train: images/train # train images (relative to 'path')
val: images/val  # val images (relative to 'path')
test: # test images (optional)

# Classes
names:
  0: watermelon
  1: wintermelon

2.使用半自动标注工具 EISeg 对数据集melon进行标注：

(1).从 PaddleSeg 中下载"通用场景的图像标注"高精度模型static_hrnet18_ocr64_cocolvis.zip；

(2).标注前先按照下面操作设置好：

1).选中JSON保存，取消COCO保存;

2).选中自动保存;

3).取消灰度保存.

3.编写Python脚本将EISeg生成的json文件转换成YOLOv8 segment支持的txt文件：

import os
import json
import argparse
import colorama
import random
import shutil
import cv2

# supported image formats
img_formats = (".bmp", ".jpeg", ".jpg", ".png", ".webp")

def parse_args():
	parser = argparse.ArgumentParser(description="json(EISeg) to txt(YOLOv8)")

	parser.add_argument("--dir", required=True, type=str, help="images directory, all json files are in the label directory, and generated txt files are also in the label directory")
	parser.add_argument("--labels", required=True, type=str, help="txt file that hold indexes and labels, one label per line, for example: face 0")
	parser.add_argument("--val_size", default=0.2, type=float, help="the proportion of the validation set to the overall dataset:[0., 0.5]")
	parser.add_argument("--name", required=True, type=str, help="the name of the dataset")

	args = parser.parse_args()
	return args

def get_labels_index(name):
	labels = {} # key,value
	with open(name, "r") as file:
		for line in file:
			# print("line:", line)

			key_value = []
			for v in line.split(" "):
				# print("v:", v)
				key_value.append(v.replace("\n", "")) # remove line breaks(\n) at the end of the line
			if len(key_value) != 2:
				print(colorama.Fore.RED + "Error: each line should have only two values(key value):", len(key_value))
				continue

			labels[key_value[0]] = key_value[1]
		
	with open(name, "r") as file:
		line_num = len(file.readlines())

	if line_num != len(labels):
		print(colorama.Fore.RED + "Error: there may be duplicate lables:", line_num, len(labels))

	return labels

def get_json_files(dir):
	jsons = []
	for x in os.listdir(dir+"/label"):
		if x.endswith(".json"):
			jsons.append(x)

	return jsons

def parse_json(name_json, name_image):
	img = cv2.imread(name_image)
	if img is None:
		print(colorama.Fore.RED + "Error: unable to load image:", name_image)
		raise
	height, width = img.shape[:2]

	with open(name_json, "r") as file:
		data = json.load(file)

		objects=[]
		for i in range(0, len(data)):
			object = []
			object.append(data[i]["name"])
			object.append(data[i]["points"])
			objects.append(object)

	return width, height, objects

def write_to_txt(name_json, width, height, objects, labels):
	name_txt = name_json[:-len(".json")] + ".txt"
	# print("name txt:", name_txt)

	with open(name_txt, "w") as file:
		for obj in objects: # 0: name; 1: points
			if len(obj[1]) < 3:
				print(colorama.Fore.RED + "Error: must be at least 3 pairs:", len(obj[1]), name_json)
				raise
			
			if obj[0] not in labels:
				print(colorama.Fore.RED + "Error: unsupported label:", obj[0], labels)
				raise

			string = ""
			for pt in obj[1]:
				string = string + " " + str(round(pt[0] / width, 6)) + " " + str(round(pt[1] / height, 6))
			
			string = labels[obj[0]] + string + "\r"
			file.write(string)

def json_to_txt(dir, jsons, labels):
	for json in jsons:
		name_json = dir + "/label/" + json
		name_image = ""

		for format in img_formats:
			file = dir + "/" + json[:-len(".json")] + format
			if os.path.isfile(file):
				name_image = file
				break

		if not name_image:
			print(colorama.Fore.RED + "Error: required image does not exist:", json[:-len(".json")])
			raise
		# print("name image:", name_image)

		width, height, objects = parse_json(name_json, name_image)
		# print(f"width: {width}; height: {height}; objects: {objects}")

		write_to_txt(name_json, width, height, objects, labels)


def get_random_sequence(length, val_size):
	numbers = list(range(0, length))
	val_sequence = random.sample(numbers, int(length*val_size))
	# print("val_sequence:", val_sequence)

	train_sequence = [x for x in numbers if x not in val_sequence]
	# print("train_sequence:", train_sequence)

	return train_sequence, val_sequence

def get_files_number(dir):
	count = 0
	for file in os.listdir(dir):
		if os.path.isfile(os.path.join(dir, file)):
			count += 1

	return count

def split_train_val(dir, jsons, name, val_size):
	if val_size > 0.5 or val_size < 0.01:
		print(colorama.Fore.RED + "Error: the interval for val_size should be:[0.01, 0.5]:", val_size)
		raise

	dst_dir_images_train = "datasets/" + name + "/images/train"
	dst_dir_images_val = "datasets/" + name + "/images/val"
	dst_dir_labels_train = "datasets/" + name + "/labels/train"
	dst_dir_labels_val = "datasets/" + name + "/labels/val"

	try:
		os.makedirs(dst_dir_images_train) #, exist_ok=True
		os.makedirs(dst_dir_images_val)
		os.makedirs(dst_dir_labels_train)
		os.makedirs(dst_dir_labels_val)
	except OSError as e:
		print(colorama.Fore.RED + "Error: cannot create directory:", e.strerror)
		raise

	# print("jsons:", jsons)
	train_sequence, val_sequence = get_random_sequence(len(jsons), val_size)

	for index in train_sequence:
		for format in img_formats:
			file = dir + "/" + jsons[index][:-len(".json")] + format
			# print("file:", file)
			if os.path.isfile(file):
				shutil.copy(file, dst_dir_images_train)
				break

		file = dir + "/label/" + jsons[index][:-len(".json")] + ".txt"
		if os.path.isfile(file):
			shutil.copy(file, dst_dir_labels_train)

	for index in val_sequence:
		for format in img_formats:
			file = dir + "/" + jsons[index][:-len(".json")] + format
			if os.path.isfile(file):
				shutil.copy(file, dst_dir_images_val)
				break

		file = dir + "/label/" + jsons[index][:-len(".json")] + ".txt"
		if os.path.isfile(file):
			shutil.copy(file, dst_dir_labels_val)

	num_images_train = get_files_number(dst_dir_images_train)
	num_images_val = get_files_number(dst_dir_images_val)
	num_labels_train = get_files_number(dst_dir_labels_train)
	num_labels_val = get_files_number(dst_dir_labels_val)

	if  num_images_train + num_images_val != len(jsons) or num_labels_train + num_labels_val != len(jsons):
		print(colorama.Fore.RED + "Error: the number of files is inconsistent:", num_images_train, num_images_val, num_labels_train, num_labels_val, len(jsons))
		raise


def generate_yaml_file(labels, name):
	path = os.path.join("datasets", name, name+".yaml")
	# print("path:", path)
	with open(path, "w") as file:
		file.write("path: ../datasets/%s # dataset root dir\n" % name)
		file.write("train: images/train # train images (relative to 'path')\n")
		file.write("val: images/val  # val images (relative to 'path')\n")
		file.write("test: # test images (optional)\n\n")

		file.write("# Classes\n")
		file.write("names:\n")
		for key, value in labels.items():
			# print(f"key: {key}; value: {value}")
			file.write("  %d: %s\n" % (int(value), key))


if __name__ == "__main__":
	colorama.init()
	args = parse_args()

	# 1. parse JSON file and write it to a TXT file
	labels = get_labels_index(args.labels)
	# print("labels:", labels)
	jsons = get_json_files(args.dir)
	# print(f"jsons: {jsons}; number: {len(jsons)}")
	json_to_txt(args.dir, jsons, labels)

	# 2. split the dataset
	split_train_val(args.dir, jsons, args.name, args.val_size)

	# 3. generate a YAML file
	generate_yaml_file(labels, args.name)

	print(colorama.Fore.GREEN + "====== execution completed ======")

以上脚本包含3个功能：

1).将json文件转换成txt文件；

2).将数据集随机拆分成训练集和测试集；

3).产生需要的yaml文件

4.编写Python脚本进行train:

import argparse
import colorama
from ultralytics import YOLO

def parse_args():
	parser = argparse.ArgumentParser(description="YOLOv8 train")
	parser.add_argument("--yaml", required=True, type=str, help="yaml file")
	parser.add_argument("--epochs", required=True, type=int, help="number of training")
	parser.add_argument("--task", required=True, type=str, choices=["detect", "segment"], help="specify what kind of task")

	args = parser.parse_args()
	return args

def train(task, yaml, epochs):
	if task == "detect":
		model = YOLO("yolov8n.pt") # load a pretrained model
	elif task == "segment":
		model = YOLO("yolov8n-seg.pt") # load a pretrained model
	else:
		print(colorama.Fore.RED + "Error: unsupported task:", task)
		raise

	results = model.train(data=yaml, epochs=epochs, imgsz=640) # train the model

	metrics = model.val() # It'll automatically evaluate the data you trained, no arguments needed, dataset and settings remembered

	model.export(format="onnx") #, dynamic=True) # export the model, cannot specify dynamic=True, opencv does not support
	# model.export(format="onnx", opset=12, simplify=True, dynamic=False, imgsz=640)
	model.export(format="torchscript") # libtorch

if __name__ == "__main__":
	colorama.init()
	args = parse_args()

	train(args.task, args.yaml, args.epochs)

	print(colorama.Fore.GREEN + "====== execution completed ======")

执行结果如下图所示：会生成best.pt、best.onnx、best.torchscript

5.生成的best.onnx使用Netron进行可视化，结果如下图所示：

说明：

1).输入：images: float32[1,3,640,640] :与YOLOv8 detect一致，大小为3通道640*640

2).输出：包括2层，output0和output1

A.output0: float32[1,38,8400] ：

a.8400：模型预测的所有box的数量，与YOLOv8 detect一致；

b.38: 每个框给出38个值：4：xc, yc, width, height；2：class, confidences；32：mask weights

B.output1: float32[1,32,160,160] :最终mask大小是160*160;output1中的masks实际上只是原型masks，并不代表最终masks。为了得到某个box的最终mask，你可以将每个mask与其对应的mask weight相乘，然后将所有这些乘积相加。此外，你可以在box上应用NMS，以获得具有特定置信度阈值的box子集

6.编写Python脚本实现predict：

import colorama
import argparse
from ultralytics import YOLO
import os

def parse_args():
	parser = argparse.ArgumentParser(description="YOLOv8 predict")
	parser.add_argument("--model", required=True, type=str, help="model file")
	parser.add_argument("--dir_images", required=True, type=str, help="directory of test images")
	parser.add_argument("--dir_result", required=True, type=str, help="directory where the image results are saved")

	args = parser.parse_args()
	return args

def get_images(dir):
	# supported image formats
	img_formats = (".bmp", ".jpeg", ".jpg", ".png", ".webp")
	images = []

	for file in os.listdir(dir):
		if os.path.isfile(os.path.join(dir, file)):
			# print(file)
			_, extension = os.path.splitext(file)
			for format in img_formats:
				if format == extension.lower():
					images.append(file)
					break

	return images

def predict(model, dir_images, dir_result):
	model = YOLO(model) # load an model
	model.info() # display model information

	images = get_images(dir_images)
	# print("images:", images)

	os.makedirs(dir_result) #, exist_ok=True)

	for image in images:
		results = model.predict(dir_images+"/"+image)
		for result in results:
			# print(result)
			result.save(dir_result+"/"+image)
			
if __name__ == "__main__":
	colorama.init()
	args = parse_args()

	predict(args.model, args.dir_images, args.dir_result)

	print(colorama.Fore.GREEN + "====== execution completed ======")

执行结果如下图所示：