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""" OpenAI pretrained model functions
Adapted from https://github.com/openai/CLIP. Originally MIT License, Copyright (c) 2021 OpenAI.
"""
import os
import warnings
from typing import List, Optional, Union
import torch
from .model import build_model_from_openai_state_dict, convert_weights_to_lp, get_cast_dtype
from .pretrained import get_pretrained_url, list_pretrained_models_by_tag, download_pretrained_from_url
__all__ = ["list_openai_models", "load_openai_model"]
def list_openai_models() -> List[str]:
"""Returns the names of available CLIP models"""
return list_pretrained_models_by_tag('openai')
def load_openai_model(
name: str,
precision: Optional[str] = None,
device: Optional[Union[str, torch.device]] = None,
jit: bool = True,
cache_dir: Optional[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
precision: str
Model precision, if None defaults to 'fp32' if device == 'cpu' else 'fp16'.
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.
cache_dir : Optional[str]
The directory to cache the downloaded model weights
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 device is None:
device = "cuda" if torch.cuda.is_available() else "cpu"
if precision is None:
precision = 'fp32' if device == 'cpu' else 'fp16'
if get_pretrained_url(name, 'openai'):
model_path = download_pretrained_from_url(get_pretrained_url(name, 'openai'), cache_dir=cache_dir)
elif os.path.isfile(name):
model_path = name
else:
raise RuntimeError(f"Model {name} not found; available models = {list_openai_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:
# Build a non-jit model from the OpenAI jitted model state dict
cast_dtype = get_cast_dtype(precision)
try:
model = build_model_from_openai_state_dict(state_dict or model.state_dict(), cast_dtype=cast_dtype)
except KeyError:
sd = {k[7:]: v for k, v in state_dict["state_dict"].items()}
model = build_model_from_openai_state_dict(sd, cast_dtype=cast_dtype)
# model from OpenAI state dict is in manually cast fp16 mode, must be converted for AMP/fp32/bf16 use
model = model.to(device)
if precision.startswith('amp') or precision == 'fp32':
model.float()
elif precision == 'bf16':
convert_weights_to_lp(model, dtype=torch.bfloat16)
return model
# 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 (typically for CPU)
if precision == 'fp32':
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()
# ensure image_size attr available at consistent location for both jit and non-jit
model.visual.image_size = model.input_resolution.item()
return model
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