import hashlib import os import urllib import warnings from typing import Union, List import torch from PIL import Image from torchvision.transforms import Compose, Resize, CenterCrop, ToTensor, Normalize from torchvision.transforms.functional import InterpolationMode from tqdm import tqdm from .model import build_model from .simple_tokenizer import SimpleTokenizer as _Tokenizer __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", "ViT-B/32": "https://openaipublic.azureedge.net/clip/models/40d365715913c9da98579312b702a82c18be219cc2a73407c4526f58eba950af/ViT-B-32.pt", } def _download(url: str, root: str = os.path.expanduser("~/.cache/clip")): 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) 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 _transform(n_px): return Compose([ Resize(n_px, interpolation=InterpolationMode.BILINEAR), CenterCrop(n_px), lambda image: image.convert("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=True): """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 (default) or more hackable non-JIT model. 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]) 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): graphs = [module.graph] if hasattr(module, "graph") else [] 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): graphs = [module.graph] if hasattr(module, "graph") else [] 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) -> 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 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: raise RuntimeError(f"Input {texts[i]} is too long for context length {context_length}") result[i, :len(tokens)] = torch.tensor(tokens) return result