main.py

import base64
from io import BytesIO

import torch
from fastapi import FastAPI, Query
from PIL import Image
from qwen_vl_utils import process_vision_info
from transformers import AutoProcessor, Qwen2_5_VLForConditionalGeneration

app = FastAPI()

checkpoint = "Qwen/Qwen2.5-VL-3B-Instruct"
min_pixels = 256 * 28 * 28
max_pixels = 1280 * 28 * 28
processor = AutoProcessor.from_pretrained(
    checkpoint, min_pixels=min_pixels, max_pixels=max_pixels
)
model = Qwen2_5_VLForConditionalGeneration.from_pretrained(
    checkpoint,
    torch_dtype=torch.bfloat16,
    device_map="auto",
    # attn_implementation="flash_attention_2",
)


@app.get("/")
def read_root():
    return {"message": "API is live. Use the /predict endpoint."}


def encode_image(image_path, max_size=(800, 800), quality=85):
    """
    Converts an image from a local file path to a Base64-encoded string with optimized size.

    Args:
        image_path (str): The path to the image file.
        max_size (tuple): The maximum width and height of the resized image.
        quality (int): The compression quality (1-100, higher means better quality but bigger size).

    Returns:
        str: Base64-encoded representation of the optimized image.
    """
    try:
        with Image.open(image_path) as img:
            # Convert to RGB (avoid issues with PNG transparency)
            img = img.convert("RGB")

            # Resize while maintaining aspect ratio
            img.thumbnail(max_size, Image.LANCZOS)

            # Save to buffer with compression
            buffer = BytesIO()
            img.save(
                buffer, format="JPEG", quality=quality
            )  # Save as JPEG to reduce size
            return base64.b64encode(buffer.getvalue()).decode("utf-8")
    except Exception as e:
        print(f"❌ Error encoding image {image_path}: {e}")
        return None


@app.get("/predict")
def predict(image_url: str = Query(...), prompt: str = Query(...)):

    image = encode_image(image_url)

    messages = [
        {
            "role": "system",
            "content": "You are a helpful assistant with vision abilities.",
        },
        {
            "role": "user",
            "content": [
                {"type": "image", "image": f"data:image;base64,{image}"},
                {"type": "text", "text": prompt},
            ],
        },
    ]
    text = processor.apply_chat_template(
        messages, tokenize=False, add_generation_prompt=True
    )
    image_inputs, video_inputs = process_vision_info(messages)
    inputs = processor(
        text=[text],
        images=image_inputs,
        videos=video_inputs,
        padding=True,
        return_tensors="pt",
    ).to(model.device)
    with torch.no_grad():
        generated_ids = model.generate(**inputs, max_new_tokens=128)
    generated_ids_trimmed = [
        out_ids[len(in_ids) :]
        for in_ids, out_ids in zip(inputs.input_ids, generated_ids)
    ]
    output_texts = processor.batch_decode(
        generated_ids_trimmed,
        skip_special_tokens=True,
        clean_up_tokenization_spaces=False,
    )
    return {"response": output_texts[0]}