摘要：国庆旅游景点人太多，拍出来的照片全是人人人、车车车，该怎么办？不妨试试这个黑科技，让你的出游vlog秒变科幻大片。
本文分享自华为云社区《国庆出游神器，魔幻黑科技换天造物，让vlog秒变科幻大片！》，作者：技术火炬手 。
国庆出游，无论是拍人、拍景或是其他，“天空”都是关键元素。比如，一张平平无奇的景物图加上落日余晖的天空色调，氛围感就有了。
当然，自然景观的天空还不是最酷炫的。今天给大家介绍一款基于原生视频的AI处理方法，不仅可以一键置换天空背景，还可以打造任意“天空之城”。
比如换成《星际迷航》中的浩瀚星空、宇宙飞船，将自己随手拍的平平无奇vlog秒变为科幻大片，画面毫无违和感。
该方法源自Github上的开源项目SkyAR，它可以自动识别天空，然后将天空从图片中切割出来，再将天空替换成目标天空，从而实现魔法换天。
下面，我们将基于SkyAR和ModelArts的JupyterLab从零开始“换天造物”。只要脑洞够大，利用这项AI技术，就可以创造出无限种玩法。
本案例在CPU和GPU下面均可运行，CPU环境运行预计花费9分钟，GPU环境运行预计花费2分钟。
实验目标
通过本案例的学习：
了解图像分割的基本应用；
了解运动估计的基本应用；
了解图像混合的基本应用。
注意事项
如果您是第一次使用 JupyterLab，请查看《ModelArts JupyterLab使用指导》了解使用方法；如果您在使用 JupyterLab 过程中碰到报错，请参考《ModelArts JupyterLab常见问题解决办法》尝试解决问题。实验步骤
1、安装和导入依赖包
import osimport moxing as moxfile_name = 'SkyAR'if not os.path.exists(file_name):mox.file.copy('obs://modelarts-labs-bj4-v2/case_zoo/SkyAR/SkyAR.zip', 'SkyAR.zip')os.system('unzip SkyAR.zip')os.system('rm SkyAR.zip')mox.file.copy_parallel('obs://modelarts-labs-bj4-v2/case_zoo/SkyAR/resnet50-19c8e357.pth', '/home/ma-user/.cache/torch/checkpoints/resnet50-19c8e357.pth')INFO:root:Using MoXing-v1.17.3-43fbf97fINFO:root:Using OBS-Python-SDK-3.20.7!pip uninstall opencv-python -y!pip uninstall opencv-contrib-python -yFound existing installation: opencv-python 4.1.2.30Uninstalling opencv-python-4.1.2.30:Successfully uninstalled opencv-python-4.1.2.30WARNING: Skipping opencv-contrib-python as it is not installed.!pip install opencv-contrib-python==4.5.3.56Looking in indexes: /repository/pypi/simpleCollecting opencv-contrib-python==4.5.3.56Downloading /repository/pypi/packages/3f/ce/36772cc6d9061b423b080e86919fd62cdef0837263f29ba6ff92e07f72d7/opencv_contrib_python-4.5.3.56-cp37-cp37m-manylinux_x86_64.whl (56.1 MB)|████████████████████████████████| 56.1 MB 166 kB/s eta 0:00:01|█████▋| 9.8 MB 9.4 MB/s eta 0:00:05 MB 9.4 MB/s eta 0:00:05███▏| 26.6 MB 9.4 MB/s eta 0:00:04/s eta 0:00:03��██▍ | 35.8 MB 9.4 MB/s eta 0:00:03�███████████▌ | 42.9 MB 9.4 MB/s eta 0:00:02��██████████████▎ | 49.6 MB 166 kB/s eta 0:00:40Requirement already satisfied: numpy>=1.14.5 in /home/ma-user/anaconda3/envs/PyTorch-1.4/lib/python3.7/site-packages (from opencv-contrib-python==4.5.3.56) (1.20.3)Installing collected packages: opencv-contrib-pythonSuccessfully installed opencv-contrib-python-4.5.3.56WARNING: You are using pip version 20.3.3; however, version 21.1.3 is available.You should consider upgrading via the '/home/ma-user/anaconda3/envs/PyTorch-1.4/bin/python -m pip install --upgrade pip' command.cd SkyAR//home/ma-user/work/Untitled Folder/SkyARimport timeimport jsonimport base64import numpy as npimport matplotlib.pyplot as pltimport cv2import argparsefrom networks import *from skyboxengine import *import utilsimport torchfrom IPython.display import clear_output, Image, display, HTML%matplotlib inline# 如果存在GPU则在GPU上面运行device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")INFO:matplotlib.font_manager:generated new fontManager
2、预览一下原视频
video_name = "test_videos/sky.mp4"def arrayShow(img):img = cv2.resize(img, (0, 0), fx=0.25, fy=0.25, interpolation=cv2.INTER_NEAREST)_,ret = cv2.imencode('.jpg', img)return Image(data=ret)# 打开一个视频流cap = cv2.VideoCapture(video_name)frame_id = 0while True:try:clear_output(wait=True) # 清除之前的显示ret, frame = cap.read() # 读取一帧图片if ret:frame_id += 1if frame_id > 200:breakcv2.putText(frame, str(frame_id), (5, 15), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 255, 0), 1) # 画frame_idtmp = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB) # 转换色彩模式img = arrayShow(frame)display(img) # 显示图片time.sleep(0.05) # 线程睡眠一段时间再处理下一帧图片else:breakexcept KeyboardInterrupt:cap.release()cap.release()
3、预览一下要替换的天空图片
img= cv2.imread('skybox/sky.jpg')img2 = img[:,:,::-1]plt.imshow(img2)<matplotlib.image.AxesImage at 0x7fbea986c590>
4、自定义训练参数
可以根据自己的需要, 修改下面的参数
skybox_center_crop: 天空体中心偏移
auto_light_matching: 自动亮度匹配
relighting_factor: 补光
recoloring_factor: 重新着色
halo_effect: 光环效应
parameter = {"net_G": "coord_resnet50","ckptdir": "./checkpoints_G_coord_resnet50","input_mode": "video","datadir": "./test_videos/sky.mp4","skybox": "sky.jpg","in_size_w": 384,"in_size_h": 384,"out_size_w": 845,"out_size_h": 480,"skybox_center_crop": 0.5,"auto_light_matching": False,"relighting_factor": 0.8,"recoloring_factor": 0.5,"halo_effect": True,"output_dir": "./jpg_output","save_jpgs": False}str_json = json.dumps(parameter)class Struct:def __init__(self, **entries):self.__dict__.update(entries)def parse_config():data = json.loads(str_json)args = Struct(**data)return argsargs = parse_config()class SkyFilter():def __init__(self, args):self.ckptdir = args.ckptdirself.datadir = args.datadirself.input_mode = args.input_modeself.in_size_w, self.in_size_h = args.in_size_w, args.in_size_hself.out_size_w, self.out_size_h = args.out_size_w, args.out_size_hself.skyboxengine = SkyBox(args)_G = define_G(input_nc=3, output_nc=1, ngf=64, netG=_G).to(device)self.load_model()self.video_writer = cv2.VideoWriter('out.avi',cv2.VideoWriter_fourcc(*'MJPG'),20.0,(args.out_size_w, args.out_size_h))self.video_writer_cat = cv2.VideoWriter('compare.avi',cv2.VideoWriter_fourcc(*'MJPG'),20.0,(2*args.out_size_w, args.out_size_h))if os.path.exists(args.output_dir) is False:os.mkdir(args.output_dir)self.output_img_list = []self.save_jpgs = args.save_jpgsdef load_model(self):# 加载预训练的天空抠图模型print('loading the best checkpoint...')checkpoint = torch.load(os.path.join(self.ckptdir, 'best_ckpt.pt'),map_location=device)_G.load_state_dict(checkpoint['model_G_state_dict'])_G.to(device)_G.eval()def write_video(self, img_HD, syneth):frame = np.array(255.0 * syneth[:, :, ::-1], dtype=np.uint8)self.video_writer.write(frame)frame_cat = np.concatenate([img_HD, syneth], axis=1)frame_cat = np.array(255.0 * frame_cat[:, :, ::-1], dtype=np.uint8)self.video_writer_cat.write(frame_cat)# 定义结果缓冲区self.output_img_list.append(frame_cat)def synthesize(self, img_HD, img_HD_prev):h, w, c = img_HD.shapeimg = cv2.resize(img_HD, (self.in_size_w, self.in_size_h))img = np.array(img, dtype=np.float32)img = torch.tensor(img).permute([2, 0, 1]).unsqueeze(0)with torch.no_grad():G_pred = _G(img.to(device))G_pred = torch.nn.functional.interpolate(G_pred,(h, w),mode='bicubic',align_corners=False)G_pred = G_pred[0, :].permute([1, 2, 0])G_pred = torch.cat([G_pred, G_pred, G_pred], dim=-1)G_pred = np.array(G_pred.detach().cpu())G_pred = np.clip(G_pred, a_max=1.0, a_min=0.0)skymask = self.skyboxengine.skymask_refinement(G_pred, img_HD)syneth = self.skyboxengine.skyblend(img_HD, img_HD_prev, skymask)return syneth, G_pred, skymaskdef cvtcolor_and_resize(self, img_HD):img_HD = cv2.cvtColor(img_HD, cv2.COLOR_BGR2RGB)img_HD = np.array(img_HD / 255., dtype=np.float32)img_HD = cv2.resize(img_HD, (self.out_size_w, self.out_size_h))return img_HDdef process_video(self):# 逐帧处理视频cap = cv2.VideoCapture(self.datadir)m_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))img_HD_prev = Nonefor idx in range(m_frames):ret, frame = cap.read()if ret:img_HD = self.cvtcolor_and_resize(frame)if img_HD_prev is None:img_HD_prev = img_HDsyneth, G_pred, skymask = self.synthesize(img_HD, img_HD_prev)self.write_video(img_HD, syneth)img_HD_prev = img_HDif (idx + 1) % 50 == 0:print(f'processing video, frame {idx + 1} / {m_frames} ... ')else: # 如果到达最后一帧break
5、替换天空
替换后输出的视频为out.avi，前后对比的视频为compare.avi
sf = SkyFilter(args)sf.process_video()initialize skybox...initialize network with normalloading the best checkpoint...processing video, frame 50 / 360 ... processing video, frame 100 / 360 ... no good point matchedprocessing video, frame 150 / 360 ... processing video, frame 200 / 360 ... processing video, frame 250 / 360 ... processing video, frame 300 / 360 ... processing video, frame 350 / 360 ...
6、对比原视频和替换后的视频
video_name = "compare.avi"def arrayShow(img):_,ret = cv2.imencode('.jpg', img)return Image(data=ret)# 打开一个视频流cap = cv2.VideoCapture(video_name)frame_id = 0while True:try:clear_output(wait=True) # 清除之前的显示ret, frame = cap.read() # 读取一帧图片if ret:frame_id += 1cv2.putText(frame, str(frame_id), (5, 15), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 255, 0), 1) # 画frame_idtmp = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB) # 转换色彩模式img = arrayShow(frame)display(img) # 显示图片time.sleep(0.05) # 线程睡眠一段时间再处理下一帧图片else:breakexcept KeyboardInterrupt:cap.release()cap.release()
如果要生成自己的视频，只要将test_videos中的sky.mp4视频和skybox中的sky.jpg图片替换成自己的视频和图片，然后重新一键运行就可以了。赶快来试一试吧，让你的国庆大片更出彩！
华为云社区祝大家国庆节快乐，度过一个开心的假期！
附录
本案例源自华为云AI Gallery：魔幻黑科技，可换天造物，秒变科幻大片！
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