import hashlib import os import urllib import warnings from typing import Any, Union, List from pkg_resources import packaging import torch from PIL import Image from torchvision.transforms import Compose, Resize, CenterCrop, ToTensor, Normalize from tqdm import tqdm from .model import build_model from .simple_tokenizer import SimpleTokenizer as _Tokenizer try: from torchvision.transforms import InterpolationMode BICUBIC = InterpolationMode.BICUBIC except ImportError: BICUBIC = Image.BICUBIC if packaging.version.parse(torch.__version__) < packaging.version.parse("1.7.1"): warnings.warn("PyTorch version 1.7.1 or higher is recommended") __all__ = ["available_models", "load", "tokenize"] _tokenizer = _Tokenizer() _MODELS = { "RN50": "https://openaipublic.azureedge.net/clip/models/afeb0e10f9e5a86da6080e35cf09123aca3b358a0c3e3b6c78a7b63bc04b6762/RN50.pt", "RN101": "https://openaipublic.azureedge.net/clip/models/8fa8567bab74a42d41c5915025a8e4538c3bdbe8804a470a72f30b0d94fab599/RN101.pt", "RN50x4": "https://openaipublic.azureedge.net/clip/models/7e526bd135e493cef0776de27d5f42653e6b4c8bf9e0f653bb11773263205fdd/RN50x4.pt", "RN50x16": "https://openaipublic.azureedge.net/clip/models/52378b407f34354e150460fe41077663dd5b39c54cd0bfd2b27167a4a06ec9aa/RN50x16.pt", "ViT-B/32": "https://openaipublic.azureedge.net/clip/models/40d365715913c9da98579312b702a82c18be219cc2a73407c4526f58eba950af/ViT-B-32.pt", "ViT-B/16": "https://openaipublic.azureedge.net/clip/models/5806e77cd80f8b59890b7e101eabd078d9fb84e6937f9e85e4ecb61988df416f/ViT-B-16.pt", } def _download(url: str, root: str): os.makedirs(root, exist_ok=True) filename = os.path.basename(url) expected_sha256 = url.split("/")[-2] download_target = os.path.join(root, filename) if os.path.exists(download_target) and not os.path.isfile(download_target): raise RuntimeError(f"{download_target} exists and is not a regular file") if os.path.isfile(download_target): if hashlib.sha256(open(download_target, "rb").read()).hexdigest() == expected_sha256: return download_target else: warnings.warn(f"{download_target} exists, but the SHA256 checksum does not match; re-downloading the file") with urllib.request.urlopen(url) as source, open(download_target, "wb") as output: with tqdm(total=int(source.info().get("Content-Length")), ncols=80, unit='iB', unit_scale=True, unit_divisor=1024) as loop: while True: buffer = source.read(8192) if not buffer: break output.write(buffer) loop.update(len(buffer)) if hashlib.sha256(open(download_target, "rb").read()).hexdigest() != expected_sha256: raise RuntimeError(f"Model has been downloaded but the SHA256 checksum does not not match") return download_target def _convert_image_to_rgb(image): return image.convert("RGB") def _transform(n_px): return Compose([ Resize(n_px, interpolation=BICUBIC), CenterCrop(n_px), _convert_image_to_rgb, ToTensor(), Normalize((0.48145466, 0.4578275, 0.40821073), (0.26862954, 0.26130258, 0.27577711)), ]) def available_models() -> List[str]: """Returns the names of available CLIP models""" return list(_MODELS.keys()) def load(name: str, device: Union[str, torch.device] = "cuda" if torch.cuda.is_available() else "cpu", jit: bool = False, download_root: str = None): """Load a CLIP model Parameters ---------- name : str A model name listed by `clip.available_models()`, or the path to a model checkpoint containing the state_dict device : Union[str, torch.device] The device to put the loaded model jit : bool Whether to load the optimized JIT model or more hackable non-JIT model (default). download_root: str path to download the model files; by default, it uses "~/.cache/clip" Returns ------- model : torch.nn.Module The CLIP model preprocess : Callable[[PIL.Image], torch.Tensor] A torchvision transform that converts a PIL image into a tensor that the returned model can take as its input """ if name in _MODELS: model_path = _download(_MODELS[name], download_root or os.path.expanduser("~/.cache/clip")) elif os.path.isfile(name): model_path = name else: raise RuntimeError(f"Model {name} not found; available models = {available_models()}") try: # loading JIT archive model = torch.jit.load(model_path, map_location=device if jit else "cpu").eval() state_dict = None except RuntimeError: # loading saved state dict if jit: warnings.warn(f"File {model_path} is not a JIT archive. Loading as a state dict instead") jit = False state_dict = torch.load(model_path, map_location="cpu") if not jit: model = build_model(state_dict or model.state_dict()).to(device) if str(device) == "cpu": model.float() return model, _transform(model.visual.input_resolution) # patch the device names device_holder = torch.jit.trace(lambda: torch.ones([]).to(torch.device(device)), example_inputs=[]) device_node = [n for n in device_holder.graph.findAllNodes("prim::Constant") if "Device" in repr(n)][-1] def patch_device(module): try: graphs = [module.graph] if hasattr(module, "graph") else [] except RuntimeError: graphs = [] if hasattr(module, "forward1"): graphs.append(module.forward1.graph) for graph in graphs: for node in graph.findAllNodes("prim::Constant"): if "value" in node.attributeNames() and str(node["value"]).startswith("cuda"): node.copyAttributes(device_node) model.apply(patch_device) patch_device(model.encode_image) patch_device(model.encode_text) # patch dtype to float32 on CPU if str(device) == "cpu": float_holder = torch.jit.trace(lambda: torch.ones([]).float(), example_inputs=[]) float_input = list(float_holder.graph.findNode("aten::to").inputs())[1] float_node = float_input.node() def patch_float(module): try: graphs = [module.graph] if hasattr(module, "graph") else [] except RuntimeError: graphs = [] if hasattr(module, "forward1"): graphs.append(module.forward1.graph) for graph in graphs: for node in graph.findAllNodes("aten::to"): inputs = list(node.inputs()) for i in [1, 2]: # dtype can be the second or third argument to aten::to() if inputs[i].node()["value"] == 5: inputs[i].node().copyAttributes(float_node) model.apply(patch_float) patch_float(model.encode_image) patch_float(model.encode_text) model.float() return model, _transform(model.input_resolution.item()) def tokenize(texts: Union[str, List[str]], context_length: int = 77, truncate: bool = False) -> torch.LongTensor: """ Returns the tokenized representation of given input string(s) Parameters ---------- texts : Union[str, List[str]] An input string or a list of input strings to tokenize context_length : int The context length to use; all CLIP models use 77 as the context length truncate: bool Whether to truncate the text in case its encoding is longer than the context length Returns ------- A two-dimensional tensor containing the resulting tokens, shape = [number of input strings, context_length] """ if isinstance(texts, str): texts = [texts] sot_token = _tokenizer.encoder["<|startoftext|>"] eot_token = _tokenizer.encoder["<|endoftext|>"] all_tokens = [[sot_token] + _tokenizer.encode(text) + [eot_token] for text in texts] result = torch.zeros(len(all_tokens), context_length, dtype=torch.long) for i, tokens in enumerate(all_tokens): if len(tokens) > context_length: if truncate: tokens = tokens[:context_length] tokens[-1] = eot_token else: raise RuntimeError(f"Input {texts[i]} is too long for context length {context_length}") result[i, :len(tokens)] = torch.tensor(tokens) return result