app.py

import torch
from torch import nn
import numpy as np
from PIL import Image
import json, os
import gradio as gr
import torchvision.transforms.functional as TF
from safetensors.torch import load_file  # Import the load_file function from safetensors
from matplotlib import cm

from models import get_model
from utils import resize_density_map, init_seeds


mean = (0.485, 0.456, 0.406)
std = (0.229, 0.224, 0.225)
alpha = 0.8
init_seeds(42)

# -----------------------------
# Define the model architecture
# -----------------------------
truncation = 4
reduction = 8
granularity = "fine"
anchor_points = "average"

model_name = "clip_vit_l_14"
input_size = 224

# Comment the lines below to test non-CLIP models.
prompt_type = "word"
num_vpt = 32
vpt_drop = 0.
deep_vpt = True

device = torch.device("cuda" if torch.cuda.is_available() else "cpu")


if truncation is None:  # regression, no truncation.
    bins, anchor_points = None, None
else:
    with open(os.path.join("configs", f"reduction_{reduction}.json"), "r") as f:
        config = json.load(f)[str(truncation)]["nwpu"]
    bins = config["bins"][granularity]
    anchor_points = config["anchor_points"][granularity]["average"] if anchor_points == "average" else config["anchor_points"][granularity]["middle"]
    bins = [(float(b[0]), float(b[1])) for b in bins]
    anchor_points = [float(p) for p in anchor_points]


model = get_model(
    backbone=model_name,
    input_size=input_size, 
    reduction=reduction,
    bins=bins,
    anchor_points=anchor_points,
    # CLIP parameters
    prompt_type=prompt_type,
    num_vpt=num_vpt,
    vpt_drop=vpt_drop,
    deep_vpt=deep_vpt
)
weights_path = os.path.join("pre-trained weights", "CLIP-EBC-ViT-L-14-NWPU", "model.safetensors")
state_dict = load_file(weights_path)
new_state_dict = {}
for k, v in state_dict.items():
    new_state_dict[k.replace("model.", "")] = v
model.load_state_dict(new_state_dict)
model.to(device)
model.eval()


# -----------------------------
# Preprocessing function
# -----------------------------
# Adjust the image transforms to match what your model expects.
def transform(image: Image.Image):
    assert isinstance(image, Image.Image), "Input must be a PIL Image"
    image_tensor = TF.to_tensor(image)

    image_height, image_width = image_tensor.shape[-2:]
    if image_height < input_size or image_width < input_size:
        # Find the ratio to resize the image while maintaining the aspect ratio
        ratio = max(input_size / image_height, input_size / image_width)
        new_height = int(image_height * ratio) + 1
        new_width = int(image_width * ratio) + 1
        image_tensor = TF.resize(image_tensor, (new_height, new_width), interpolation=TF.InterpolationMode.BICUBIC, antialias=True)

    image_tensor = TF.normalize(image_tensor, mean=mean, std=std)
    return image_tensor.unsqueeze(0)  # Add batch dimension



# -----------------------------
# Inference function
# -----------------------------
def predict(image: Image.Image):
    """
    Given an input image, preprocess it, run the model to obtain a density map,
    compute the total crowd count, and prepare the density map for display.
    """
    # Preprocess the image
    input_width, input_height = image.size
    input_tensor = transform(image).to(device)  # shape: (1, 3, H, W)
    
    with torch.no_grad():
        density_map = model(input_tensor)  # expected shape: (1, 1, H, W)
        total_count = density_map.sum().item()
        resized_density_map = resize_density_map(density_map, (input_height, input_width)).cpu().squeeze().numpy()
    
    # Normalize the density map for display purposes
    eps = 1e-8
    density_map_norm = (resized_density_map - resized_density_map.min()) / (resized_density_map.max() - resized_density_map.min() + eps)
    
    # Apply a colormap (e.g., 'jet') to get an RGBA image
    colormap = cm.get_cmap("jet")
    # The colormap returns values in [0,1]. Scale to [0,255] and convert to uint8.
    density_map_color = (colormap(density_map_norm) * 255).astype(np.uint8)
    density_map_color_img = Image.fromarray(density_map_color).convert("RGBA")
    
    # Ensure the original image is in RGBA format.
    image_rgba = image.convert("RGBA")
    overlayed_image = Image.blend(image_rgba, density_map_color_img, alpha=alpha)
    
    return image, overlayed_image, f"Predicted Count: {total_count:.2f}"


# -----------------------------
# Build Gradio Interface using Blocks for a two-column layout
# -----------------------------
with gr.Blocks() as demo:
    gr.Markdown("# Crowd Counting Demo")
    gr.Markdown("Upload an image or select an example below to see the predicted crowd density map and total count.")
    
    with gr.Row():
        with gr.Column():
            input_img = gr.Image(
                label="Input Image",
                sources=["upload", "clipboard"],
                type="pil",
            )
            submit_btn = gr.Button("Predict")
        with gr.Column():
            output_img = gr.Image(label="Predicted Density Map", type="pil")
            output_text = gr.Textbox(label="Total Count")
    
    submit_btn.click(fn=predict, inputs=input_img, outputs=[input_img, output_img, output_text])
    
    # Optional: add example images. Ensure these files are in your repo.
    gr.Examples(
        examples=[
            ["example1.jpg"],
            ["example2.jpg"]
        ],
        inputs=input_img,
        label="Try an example"
    )

# Launch the app
demo.launch(share=True)