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ai-toolkit/extensions_built_in/captioner/Qwen3VLCaptioner.py
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2026-08-27 11:53:08 -06:00

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6.0 KiB
Python

from transformers import (
AutoModelForImageTextToText,
AutoProcessor,
StoppingCriteria,
StoppingCriteriaList,
)
from collections import OrderedDict
import torch
import torch.nn.functional as F
from optimum.quanto import freeze
from toolkit.basic import flush
from toolkit.util.quantize import quantize, get_qtype
from toolkit.models.v2.text_encoders.qwen3_vl import patch_qwen_vl_patch_embed
from .BaseCaptioner import BaseCaptioner
import transformers
import logging
import traceback
import warnings
# transformers.logging.set_verbosity_error()
warnings.filterwarnings("ignore")
logging.disable(logging.WARNING)
# hard cap on reasoning tokens so a runaway think block cannot generate forever
MAX_THINKING_TOKENS = 4096
class ThinkingBudgetCriteria(StoppingCriteria):
"""For thinking models: lets the model reason freely, then counts
max_new_tokens starting from the token after </think> so the visible answer
gets the full budget regardless of how long the reasoning ran."""
def __init__(self, think_end_token_id: int, max_new_tokens: int):
self.think_end_token_id = think_end_token_id
self.max_new_tokens = max_new_tokens
self.answer_start = None
def __call__(self, input_ids, scores, **kwargs):
if self.answer_start is None:
if input_ids[0, -1].item() == self.think_end_token_id:
self.answer_start = input_ids.shape[1]
return False
return (input_ids.shape[1] - self.answer_start) >= self.max_new_tokens
class Qwen3VLCaptioner(BaseCaptioner):
def __init__(self, process_id: int, job, config: OrderedDict, **kwargs):
super(Qwen3VLCaptioner, self).__init__(process_id, job, config, **kwargs)
def load_model(self):
self.print_and_status_update("Loading Qwen3VL model")
self.model = AutoModelForImageTextToText.from_pretrained(
self.caption_config.model_name_or_path,
dtype=self.torch_dtype,
device_map="cpu",
)
# swap the slow bf16 Conv3d patch_embed for an equivalent fast linear
patch_qwen_vl_patch_embed(self.model)
if not self.caption_config.low_vram:
self.model.to(self.device_torch)
if self.caption_config.quantize:
self.print_and_status_update("Quantizing Qwen3VL model")
# in low vram mode the model stays on cpu; quantize each layer on the
# gpu and move it back so the math is fast without holding the whole
# model in vram
# lm_head is huge (vocab x hidden) and quality-critical; quantizing it
# needs a ~4x transient allocation that can OOM, so keep it in full
# precision
quantize(
self.model,
weights=get_qtype(self.caption_config.qtype),
exclude=["lm_head", "*.lm_head"],
quantize_device=self.device_torch
if self.caption_config.low_vram
else None,
)
freeze(self.model)
flush()
self.processor = AutoProcessor.from_pretrained(
self.caption_config.model_name_or_path
)
if self.caption_config.low_vram:
self.model.to(self.device_torch)
flush()
def get_caption_for_file(self, file_path: str) -> str:
img = self.load_pil_image(file_path, max_res=self.caption_config.max_res)
try:
messages = [
{
"role": "user",
"content": [
{
"type": "image",
"image": img,
},
{"type": "text", "text": self.caption_config.caption_prompt},
],
}
]
# Preparation for inference
inputs = self.processor.apply_chat_template(
messages,
tokenize=True,
add_generation_prompt=True,
return_dict=True,
return_tensors="pt",
enable_thinking=self.caption_config.thinking,
)
inputs = inputs.to(self.device_torch)
gen_kwargs = {"max_new_tokens": self.caption_config.max_new_tokens}
if self.caption_config.thinking:
think_end_token_id = self.processor.tokenizer.convert_tokens_to_ids(
"</think>"
)
if think_end_token_id is not None:
# give the model room to think, but start the max_new_tokens
# budget only once the think block closes
gen_kwargs = {
"max_new_tokens": MAX_THINKING_TOKENS
+ self.caption_config.max_new_tokens,
"stopping_criteria": StoppingCriteriaList(
[
ThinkingBudgetCriteria(
think_end_token_id,
self.caption_config.max_new_tokens,
)
]
),
}
# Inference: Generation of the output
generated_ids = self.model.generate(**inputs, **gen_kwargs)
generated_ids_trimmed = [
out_ids[len(in_ids) :]
for in_ids, out_ids in zip(inputs.input_ids, generated_ids)
]
output_text = self.processor.batch_decode(
generated_ids_trimmed,
skip_special_tokens=True,
clean_up_tokenization_spaces=False,
)
caption = output_text[0]
# thinking models (e.g. Qwen3.6) may still emit reasoning before the
# answer; keep only what follows the think block
if "</think>" in caption:
caption = caption.split("</think>")[-1]
return caption.strip()
except Exception as e:
print(f"Error processing {file_path}: {e}")
traceback.print_exc()
return None