Ottimizzare Gemma per le attività di visione utilizzando Hugging Face Transformers e QLoRA

# Install Pytorch & other libraries
%pip install torch tensorboard torchvision

# Install Transformers
%pip install transformers

# Install Hugging Face libraries
%pip install datasets accelerate evaluate bitsandbytes trl peft protobuf pillow sentencepiece

# COMMENT IN: if you are running on a GPU that supports BF16 data type and flash attn, such as NVIDIA L4 or NVIDIA A100
#%pip install flash-attn

# Login into Hugging Face Hub
from huggingface_hub import login
login()

{"messages": [{"role": "system", "content": [{"type": "text", "text":"You are..."}]}, {"role": "user", "content": [{"type": "text", "text": "..."}, {"type": "image"}]}, {"role": "assistant", "content": [{"type": "text", "text": "..."}]}]}
{"messages": [{"role": "system", "content": [{"type": "text", "text":"You are..."}]}, {"role": "user", "content": [{"type": "text", "text": "..."}, {"type": "image"}]}, {"role": "assistant", "content": [{"type": "text", "text": "..."}]}]}
{"messages": [{"role": "system", "content": [{"type": "text", "text":"You are..."}]}, {"role": "user", "content": [{"type": "text", "text": "..."}, {"type": "image"}]}, {"role": "assistant", "content": [{"type": "text", "text": "..."}]}]}

from datasets import load_dataset
from PIL import Image

# System message for the assistant
system_message = "You are an expert product description writer for Amazon."

# User prompt that combines the user query and the schema
user_prompt = """Create a Short Product description based on the provided <PRODUCT> and <CATEGORY> and image.
Only return description. The description should be SEO optimized and for a better mobile search experience.

<PRODUCT>
{product}
</PRODUCT>

<CATEGORY>
{category}
</CATEGORY>
"""

# Convert dataset to OAI messages
def format_data(sample):
    return {
        "messages": [
            {
                "role": "system",
                #"content": [{"type": "text", "text": system_message}],
                "content": system_message,
            },
            {
                "role": "user",
                "content": [
                    {
                        "type": "text",
                        "text": user_prompt.format(
                            product=sample["Product Name"],
                            category=sample["Category"],
                        ),
                    },
                    {
                        "type": "image",
                        "image": sample["image"],
                    },
                ],
            },
            {
                "role": "assistant",
                "content": [{"type": "text", "text": sample["description"]}],
            },
        ],
    }

def process_vision_info(messages: list[dict]) -> list[Image.Image]:
    image_inputs = []
    # Iterate through each conversation
    for msg in messages:
        # Get content (ensure it's a list)
        content = msg.get("content", [])
        if not isinstance(content, list):
            content = [content]

        # Check each content element for images
        for element in content:
            if isinstance(element, dict) and (
                "image" in element or element.get("type") == "image"
            ):
                # Get the image and convert to RGB
                if "image" in element:
                    image = element["image"]
                else:
                    image = element
                image_inputs.append(image.convert("RGB"))
    return image_inputs

# Load dataset from the hub
dataset = load_dataset("philschmid/amazon-product-descriptions-vlm", split="train")
dataset = dataset.train_test_split(test_size=0.1)

# Convert dataset to OAI messages
# need to use list comprehension to keep Pil.Image type, .mape convert image to bytes
dataset_train = [format_data(sample) for sample in dataset["train"]]
dataset_test = [format_data(sample) for sample in dataset["test"]]

print(dataset_train[345]["messages"])

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[{'role': 'system', 'content': 'You are an expert product description writer for Amazon.'}, {'role': 'user', 'content': [{'type': 'text', 'text': "Create a Short Product description based on the provided <PRODUCT> and <CATEGORY> and image.\nOnly return description. The description should be SEO optimized and for a better mobile search experience.\n\n<PRODUCT>\nRazor Agitator BMX/Freestyle Bike, 20-Inch\n</PRODUCT>\n\n<CATEGORY>\nSports & Outdoors | Outdoor Recreation | Cycling | Kids' Bikes & Accessories | Kids' Bikes\n</CATEGORY>\n"}, {'type': 'image', 'image': <PIL.JpegImagePlugin.JpegImageFile image mode=RGB size=500x413 at 0x7B7250181790>}]}, {'role': 'assistant', 'content': [{'type': 'text', 'text': 'Conquer the streets with the Razor Agitator BMX Bike! This 20-inch freestyle bike is built for young riders ready to take on any challenge. Durable frame, responsive handling – perfect for tricks and cruising.  Get yours today!'}]}]

import torch
from transformers import AutoProcessor, AutoModelForImageTextToText, BitsAndBytesConfig

# Hugging Face model id
model_id = "google/gemma-4-E2B" # @param ["google/gemma-4-E2B","google/gemma-4-E4B"] {"allow-input":true}

# Check if GPU benefits from bfloat16
if torch.cuda.get_device_capability()[0] < 8:
    raise ValueError("GPU does not support bfloat16, please use a GPU that supports bfloat16.")

# Define model init arguments
model_kwargs = dict(
    dtype=torch.bfloat16, # What torch dtype to use, defaults to auto
    device_map="auto", # Let torch decide how to load the model
)

# BitsAndBytesConfig int-4 config
model_kwargs["quantization_config"] = BitsAndBytesConfig(
    load_in_4bit=True,
    bnb_4bit_use_double_quant=True,
    bnb_4bit_quant_type="nf4",
    bnb_4bit_compute_dtype=model_kwargs["dtype"],
    bnb_4bit_quant_storage=model_kwargs["dtype"],
)

# Load model and tokenizer
model = AutoModelForImageTextToText.from_pretrained(model_id, **model_kwargs)
processor = AutoProcessor.from_pretrained("google/gemma-4-E2B-it") # Load the Instruction Tokenizer to use the official Gemma template

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from peft import LoraConfig

peft_config = LoraConfig(
    lora_alpha=16,
    lora_dropout=0.05,
    r=16,
    bias="none",
    target_modules="all-linear",
    task_type="CAUSAL_LM",
    modules_to_save=["lm_head", "embed_tokens"], # make sure to save the lm_head and embed_tokens as you train the special tokens
    ensure_weight_tying=True,
)

from trl import SFTConfig

args = SFTConfig(
    output_dir="gemma-product-description",     # directory to save and repository id
    num_train_epochs=3,                         # number of training epochs
    per_device_train_batch_size=1,              # batch size per device during training
    optim="adamw_torch_fused",                  # use fused adamw optimizer
    logging_steps=5,                            # log every 5 steps
    save_strategy="epoch",                      # save checkpoint every epoch
    eval_strategy="epoch",                      # evaluate checkpoint every epoch
    learning_rate=2e-4,                         # learning rate, based on QLoRA paper
    bf16=True,                                  # use bfloat16 precision
    max_grad_norm=0.3,                          # max gradient norm based on QLoRA paper
    lr_scheduler_type="constant",               # use constant learning rate scheduler
    push_to_hub=True,                           # push model to hub
    report_to="tensorboard",                    # report metrics to tensorboard
    dataset_text_field="",                      # need a dummy field for collator
    dataset_kwargs={"skip_prepare_dataset": True}, # important for collator
    remove_unused_columns = False               # important for collator
)

# Create a data collator to encode text and image pairs
def collate_fn(examples):
    texts = []
    images = []
    for example in examples:
        image_inputs = process_vision_info(example["messages"])
        text = processor.apply_chat_template(
            example["messages"], add_generation_prompt=False, tokenize=False
        )
        texts.append(text.strip())
        images.append(image_inputs)

    # Tokenize the texts and process the images
    batch = processor(text=texts, images=images, return_tensors="pt", padding=True)

    # The labels are the input_ids, and we mask the padding tokens and image tokens in the loss computation
    labels = batch["input_ids"].clone()

    # Mask tokens for not being used in the loss computation
    labels[labels == processor.tokenizer.pad_token_id] = -100
    labels[labels == processor.tokenizer.boi_token_id] = -100
    labels[labels == processor.tokenizer.image_token_id] = -100
    labels[labels == processor.tokenizer.eoi_token_id] = -100

    batch["labels"] = labels
    return batch

from trl import SFTTrainer

# Create Trainer object
trainer = SFTTrainer(
    model=model,
    args=args,
    train_dataset=dataset_train,
    eval_dataset=dataset_test,
    peft_config=peft_config,
    processing_class=processor,
    data_collator=collate_fn,
)

# Start training, the model will be automatically saved to the Hub and the output directory
trainer.train()

# Save the final model again to the Hugging Face Hub
trainer.save_model()

The tokenizer has new PAD/BOS/EOS tokens that differ from the model config and generation config. The model config and generation config were aligned accordingly, being updated with the tokenizer's values. Updated tokens: {'eos_token_id': 1, 'bos_token_id': 2, 'pad_token_id': 0}.

# free the memory again
del model
del trainer
torch.cuda.empty_cache()

from peft import PeftModel

# Load Model base model
model = AutoModelForImageTextToText.from_pretrained(model_id, low_cpu_mem_usage=True)

# Merge LoRA and base model and save
peft_model = PeftModel.from_pretrained(model, args.output_dir)
merged_model = peft_model.merge_and_unload()
merged_model.save_pretrained("merged_model", safe_serialization=True, max_shard_size="2GB")

processor = AutoProcessor.from_pretrained(args.output_dir)
processor.save_pretrained("merged_model")

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['merged_model/processor_config.json']

model_id = "merged_model"

# Load Model with PEFT adapter
model = AutoModelForImageTextToText.from_pretrained(
  model_id,
  device_map="auto",
  dtype="auto",
)
processor = AutoProcessor.from_pretrained(model_id)

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The tied weights mapping and config for this model specifies to tie model.language_model.embed_tokens.weight to lm_head.weight, but both are present in the checkpoints with different values, so we will NOT tie them. You should update the config with `tie_word_embeddings=False` to silence this warning.

import requests
from PIL import Image

# Test sample with Product Name, Category and Image
sample = {
  "product_name": "Hasbro Marvel Avengers-Serie Marvel Assemble Titan-Held, Iron Man, 30,5 cm Actionfigur",
  "category": "Toys & Games | Toy Figures & Playsets | Action Figures",
  "image": Image.open(requests.get("https://m.media-amazon.com/images/I/81+7Up7IWyL._AC_SY300_SX300_.jpg", stream=True).raw).convert("RGB")
}

def generate_description(sample, model, processor):
    # Convert sample into messages and then apply the chat template
    messages = [
        {"role": "system", "content": system_message},
        {"role": "user", "content": [
            {"type": "image","image": sample["image"]},
            {"type": "text", "text": user_prompt.format(product=sample["product_name"], category=sample["category"])},
        ]},
    ]
    text = processor.apply_chat_template(
        messages, tokenize=False, add_generation_prompt=True
    )
    print(text)
    # Process the image and text
    image_inputs = process_vision_info(messages)
    # Tokenize the text and process the images
    inputs = processor(
        text=[text],
        images=image_inputs,
        padding=True,
        return_tensors="pt",
    )
    # Move the inputs to the device
    inputs = inputs.to(model.device)

    # Generate the output
    stop_token_ids = [processor.tokenizer.eos_token_id, processor.tokenizer.convert_tokens_to_ids("<turn|>")]
    generated_ids = model.generate(**inputs, max_new_tokens=256, top_p=1.0, do_sample=True, temperature=0.8, eos_token_id=stop_token_ids, disable_compile=True)
    # Trim the generation and decode the output to text
    generated_ids_trimmed = [out_ids[len(in_ids) :] for in_ids, out_ids in zip(inputs.input_ids, generated_ids)]
    output_text = processor.batch_decode(
        generated_ids_trimmed, skip_special_tokens=True, clean_up_tokenization_spaces=False
    )
    return output_text[0]

# generate the description
description = generate_description(sample, model, processor)
print("MODEL OUTPUT>> \n")
print(description)

<bos><|turn>system
You are an expert product description writer for Amazon.<turn|>
<|turn>user


<|image|>

Create a Short Product description based on the provided <PRODUCT> and <CATEGORY> and image.
Only return description. The description should be SEO optimized and for a better mobile search experience.

<PRODUCT>
Hasbro Marvel Avengers-Serie Marvel Assemble Titan-Held, Iron Man, 30,5 cm Actionfigur
</PRODUCT>

<CATEGORY>
Toys & Games | Toy Figures & Playsets | Action Figures
</CATEGORY><turn|>
<|turn>model

MODEL OUTPUT>> 

Enhance your collection with the Marvel Avengers - Avengers Assemble Ultron-Comforter Set! This soft and cuddly blanket and pillowcase feature everyone's favorite Avengers, Iron Man, and his loyal companion War Machine. Officially licensed by Marvel.  Bring home the heroic team!