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clip.py
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clip.py
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"""
MIT License
Copyright (c) 2021 OpenAI
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""
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 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=Image.BICUBIC),
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