202 lines
7.3 KiB
Python
202 lines
7.3 KiB
Python
import torch
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import torchvision.transforms as T
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from PIL import Image
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from torchvision.transforms.functional import InterpolationMode
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import requests
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from io import BytesIO
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from urllib.parse import urlparse
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IMAGENET_MEAN = (0.485, 0.456, 0.406)
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IMAGENET_STD = (0.229, 0.224, 0.225)
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def build_transform(input_size):
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transform = T.Compose([
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T.Lambda(lambda img: img.convert('RGB') if img.mode != 'RGB' else img),
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T.Resize((input_size, input_size), interpolation=InterpolationMode.BICUBIC),
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T.ToTensor(),
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T.Normalize(mean=IMAGENET_MEAN, std=IMAGENET_STD)
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])
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return transform
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def find_closest_aspect_ratio(aspect_ratio, target_ratios, width, height, image_size):
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best_ratio_diff = float('inf')
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best_ratio = (1, 1)
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area = width * height
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for ratio in target_ratios:
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target_aspect_ratio = ratio[0] / ratio[1]
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ratio_diff = abs(aspect_ratio - target_aspect_ratio)
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if ratio_diff < best_ratio_diff:
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best_ratio_diff = ratio_diff
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best_ratio = ratio
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elif ratio_diff == best_ratio_diff:
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if area > 0.5 * image_size * image_size * ratio[0] * ratio[1]:
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best_ratio = ratio
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return best_ratio
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def dynamic_preprocess(image, min_num=1, max_num=12, image_size=448, use_thumbnail=False):
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orig_width, orig_height = image.size
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aspect_ratio = orig_width / orig_height
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target_ratios = set(
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(i, j) for n in range(min_num, max_num + 1)
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for i in range(1, n + 1)
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for j in range(1, n + 1)
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if i * j <= max_num and i * j >= min_num
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)
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target_ratios = sorted(target_ratios, key=lambda x: x[0] * x[1])
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target_aspect_ratio = find_closest_aspect_ratio(
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aspect_ratio, target_ratios, orig_width, orig_height, image_size)
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target_width = image_size * target_aspect_ratio[0]
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target_height = image_size * target_aspect_ratio[1]
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blocks = target_aspect_ratio[0] * target_aspect_ratio[1]
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resized_img = image.resize((target_width, target_height))
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processed_images = []
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for i in range(blocks):
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box = (
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(i % (target_width // image_size)) * image_size,
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(i // (target_width // image_size)) * image_size,
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((i % (target_width // image_size)) + 1) * image_size,
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((i // (target_width // image_size)) + 1) * image_size
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)
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split_img = resized_img.crop(box)
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processed_images.append(split_img)
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assert len(processed_images) == blocks
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if use_thumbnail and len(processed_images) != 1:
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thumbnail_img = image.resize((image_size, image_size))
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processed_images.append(thumbnail_img)
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return processed_images
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def load_image(image_file, input_size=448, max_num=12):
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# 处理不同类型的输入
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if isinstance(image_file, Image.Image):
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image = image_file.convert('RGB')
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elif isinstance(image_file, str) and bool(urlparse(image_file).netloc):
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try:
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response = requests.get(image_file, timeout=10)
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response.raise_for_status()
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image = Image.open(BytesIO(response.content)).convert('RGB')
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except Exception as e:
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raise ValueError(f"无法从URL加载图片: {str(e)}")
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elif isinstance(image_file, str):
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image = Image.open(image_file).convert('RGB')
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elif isinstance(image_file, bytes):
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image = Image.open(BytesIO(image_file)).convert('RGB')
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else:
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raise ValueError(f"不支持的图片格式: {type(image_file)}")
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transform = build_transform(input_size=input_size)
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images = dynamic_preprocess(image, image_size=input_size, use_thumbnail=True, max_num=max_num)
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pixel_values = [transform(image) for image in images]
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pixel_values = torch.stack(pixel_values)
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return pixel_values
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def prepare_training_data(question: str, answer: str, tokenizer, image_path=None, input_size=448, max_num=12, num_image_token: int = 256):
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"""
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准备完整的训练数据（包括输入和标签）
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Args:
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question (str): 用户输入的问题
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answer (str): 助手的回答文本
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tokenizer: 分词器
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image_path: 图片路径、URL或PIL Image对象
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input_size (int): 图片输入尺寸
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max_num (int): 最大图片块数
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num_image_token (int): 每张图片的token数量
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Returns:
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dict: 包含模型训练所需的所有输入
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"""
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# 1. 处理图像输入
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pixel_values = None
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if image_path is not None:
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pixel_values = load_image(image_path, input_size=input_size, max_num=max_num)[-1:] ### 只取最后一张图片
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if torch.cuda.is_available():
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pixel_values = pixel_values.to(torch.bfloat16)
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# 2. 确保问题包含图片标记
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if pixel_values is not None and '<image>' not in question:
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question = '<image>\n' + question
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# 3. 根据pixel_values确定num_patches
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num_patches = pixel_values.shape[0] if pixel_values is not None else 0
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# 4. 构造完整的对话内容
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system_msg = "你是书生·万象，英文名是InternVL，是由上海人工智能实验室、清华大学及多家合作单位联合开发的多模态大语言模型。"
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# 5. 替换图片标记
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if num_patches > 0:
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image_tokens = "<img>" + "<IMG_CONTEXT>" * (num_image_token * num_patches) + "</img>"
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question = question.replace('<image>', image_tokens, 1)
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# 6. 构造完整的query（包含答案）
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full_prompt = (
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f"<|im_start|>system\n{system_msg}<|im_end|>\n"
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f"<|im_start|>user\n{question}<|im_end|>\n"
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f"<|im_start|>assistant\n{answer}<|im_end|>\n"
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)
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# 7. 转换为模型输入格式
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model_inputs = tokenizer(
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full_prompt,
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return_tensors="pt",
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add_special_tokens=False
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)
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# 8. 构造labels
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input_ids = model_inputs["input_ids"]
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labels = input_ids.clone()
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assistant_start_token = "<|im_start|>assistant\n"
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assistant_token_ids = tokenizer(assistant_start_token, add_special_tokens=False)["input_ids"]
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assistant_start_pos = None
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for i in range(len(input_ids[0]) - len(assistant_token_ids)):
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if input_ids[0][i:i+len(assistant_token_ids)].tolist() == assistant_token_ids:
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assistant_start_pos = i
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break
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if assistant_start_pos is not None:
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labels[0, :assistant_start_pos] = -100
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return {
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"input_ids": input_ids,
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"attention_mask": model_inputs["attention_mask"],
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"labels": labels,
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"pixel_values": pixel_values
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}
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# 使用示例：
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"""
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import torch
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from transformers import AutoTokenizer
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# 初始化tokenizer
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tokenizer = AutoTokenizer.from_pretrained("path_to_tokenizer")
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# 准备示例数据
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question = "请描述这张图片中的内容"
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answer = "这是一张美丽的风景照，画面中有青山绿水。"
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image_path = "./examples/image1.jpg" # 或URL，或PIL Image对象
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# 准备训练数据
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training_data = prepare_training_data(
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question=question,
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answer=answer,
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tokenizer=tokenizer,
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image_path=image_path,
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input_size=448,
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max_num=12
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)
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# training_data 包含:
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# {
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# "input_ids": tensor([[...]]), # 完整对话的token ids
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# "attention_mask": tensor([[...]]), # 注意力掩码
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# "labels": tensor([[...]]), # 带有-100标记的标签
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# "pixel_values": tensor([[...]]) # 图像数据
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# }
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""" |