app.py

import gradio as gr
import torch
from torchvision import transforms
from model import UNet
from PIL import Image
import numpy as np

# --- Configuration ---
MODES = [
    "MP+Tr+BCE",
    "MP+Tr+Dice",
    "StrConv+Tr+BCE",
    "StrConv+Ups+Dice"
]

def get_config(mode_name):
    if mode_name == "MP+Tr+BCE":
        return {"downsample": "maxpool", "upsample": "transpose", "filename": "unet_MP_Tr_BCE.pth"}
    elif mode_name == "MP+Tr+Dice":
        return {"downsample": "maxpool", "upsample": "transpose", "filename": "unet_MP_Tr_Dice.pth"}
    elif mode_name == "StrConv+Tr+BCE":
        return {"downsample": "strided", "upsample": "transpose", "filename": "unet_StrConv_Tr_BCE.pth"}
    elif mode_name == "StrConv+Ups+Dice":
        return {"downsample": "strided", "upsample": "upsample", "filename": "unet_StrConv_Ups_Dice.pth"}
    else:
        raise ValueError(f"Unknown mode: {mode_name}")

# --- Load Models Once (Optional optimization, but safer to load on demand if memory is tight) ---
# For immediate responsiveness, let's load them on demand inside the functions or keep them cached.
# Given it's a demo, loading 4 models might be heavy on CPU/RAM if hosted on free tier. 
# But let's try to run them sequentially.

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

def run_inference_single_model(model, image_tensor):
    with torch.no_grad():
        output = model(image_tensor)
        output = torch.sigmoid(output)
        output = output.squeeze().cpu().numpy()
    mask = (output > 0.5).astype(np.float32)
    return mask

def predict_all(image):
    if image is None:
        return [None] * 4
    
    # Preprocess
    transform = transforms.Compose([
        transforms.Resize((128, 128)),
        transforms.ToTensor()
    ])
    input_tensor = transform(image).unsqueeze(0).to(device)
    
    # Create overlay
    # Transform image to numpy for blending. We need it in [0,1] or [0,255]
    img_resized = image.resize((128, 128))
    img_np = np.array(img_resized)
    
    results = []
    
    for mode in MODES:
        config = get_config(mode)
        # Initialize model structure
        model = UNet(n_channels=3, n_classes=1, 
                     downsample_mode=config['downsample'], 
                     upsample_mode=config['upsample']).to(device)
        
        # Load weights
        try:
            model.load_state_dict(torch.load(config['filename'], map_location=device))
            model.eval()
            mask = run_inference_single_model(model, input_tensor)
            
            # Create Overlay
            # Mask is (128, 128). We want to make it Red where mask is 1.
            # Convert mask to RGBA
            overlay = np.zeros_like(img_np)
            # Set Red channel to 255 where mask is 1
            overlay[:,:,0] = mask * 255 
            # overlay[:,:,1] = 0
            # overlay[:,:,2] = 0
            
            # Blend: 0.7 * Original + 0.3 * Red Overlay (where mask is present)
            # Actually simplest is just simpler blending
            
            # Where mask == 1, add red tint
            # Let's perform a weighted add using OpenCV logic manually
            
            blended = img_np.copy()
            # Indices where mask is active
            idx = (mask > 0)
            
            # Increase Red component, decrease Green/Blue to make it pop
            blended[idx, 0] = np.clip(blended[idx, 0] * 0.5 + 255 * 0.5, 0, 255)
            blended[idx, 1] = blended[idx, 1] * 0.5
            blended[idx, 2] = blended[idx, 2] * 0.5
            
            results.append(blended)

        except Exception as e:
            print(f"Error for {mode}: {e}")
            results.append(img_np) # Return original image on error

    return results

# --- Gradio App ---
title = "UNet Oxford-IIIT Pet Separation - Model Comparison"
description = "Compare the segmentation results of 4 different UNet configurations on the same input image."

iface = gr.Interface(
    fn=predict_all,
    inputs=gr.Image(type="pil", label="Input Image"),
    outputs=[
        gr.Image(label="MP + Tr + BCE"),
        gr.Image(label="MP + Tr + Dice"),
        gr.Image(label="StrConv + Tr + BCE"),
        gr.Image(label="StrConv + Ups + Dice")
    ],
    title=title,
    description=description
)

if __name__ == "__main__":
    iface.launch()