final_diagnosis.py

import torch
from model import SmoothDiffusionUNet
from noise_scheduler import FrequencyAwareNoise
from config import Config
from torchvision.utils import save_image, make_grid
from dataloader import get_dataloaders
import numpy as np

def diagnose_and_fix():
    """Final diagnosis and alternative sampling approach"""
    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
    
    # Load model
    checkpoint = torch.load('model_final.pth', map_location=device)
    config = Config()
    
    model = SmoothDiffusionUNet(config).to(device)
    noise_scheduler = FrequencyAwareNoise(config)
    model.load_state_dict(checkpoint)
    model.eval()
    
    print("=== FINAL DIAGNOSIS ===")
    
    # Load some real training data to compare
    train_loader, _ = get_dataloaders(config)
    real_batch, _ = next(iter(train_loader))
    real_images = real_batch[:4].to(device)
    
    print(f"Real training data range: [{real_images.min():.3f}, {real_images.max():.3f}]")
    print(f"Real training data mean: {real_images.mean():.3f}, std: {real_images.std():.3f}")
    
    # Save real images for comparison
    real_display = torch.clamp((real_images + 1) / 2, 0, 1)
    real_grid = make_grid(real_display, nrow=2, normalize=False, pad_value=1.0)
    save_image(real_grid, "real_training_images.png")
    print("Real training images saved to real_training_images.png")
    
    with torch.no_grad():
        # Test model on real data at different noise levels
        print("\n=== TESTING MODEL ON REAL DATA ===")
        
        for t_val in [50, 200, 400]:
            t_tensor = torch.full((4,), t_val, device=device, dtype=torch.long)
            
            # Add noise to real image
            x_noisy, noise_target = noise_scheduler.apply_noise(real_images, t_tensor)
            
            # Get model prediction
            noise_pred = model(x_noisy, t_tensor)
            
            # Try to reconstruct
            alpha_bar_t = noise_scheduler.alpha_bars[t_val].item()
            x_reconstructed = (x_noisy - np.sqrt(1 - alpha_bar_t) * noise_pred) / np.sqrt(alpha_bar_t)
            x_reconstructed = torch.clamp(x_reconstructed, -1, 1)
            
            print(f"\nTimestep {t_val}:")
            print(f"  Reconstruction error: {torch.mean((x_reconstructed - real_images) ** 2).item():.6f}")
            
            # Save reconstruction
            recon_display = torch.clamp((x_reconstructed + 1) / 2, 0, 1)
            recon_grid = make_grid(recon_display, nrow=2, normalize=False)
            save_image(recon_grid, f"reconstruction_t{t_val}.png")
            print(f"  Reconstruction saved to reconstruction_t{t_val}.png")
        
        print("\n=== TRYING INTERPOLATION SAMPLING ===")
        
        # Instead of starting from pure noise, interpolate between real images
        x1 = real_images[0:1]  # First real image
        x2 = real_images[1:2]  # Second real image
        
        # Create interpolations
        alphas = torch.linspace(0, 1, 4, device=device).view(-1, 1, 1, 1)
        x_interp = torch.cat([
            alpha * x1 + (1 - alpha) * x2 for alpha in alphas
        ], dim=0)
        
        print(f"Starting from real image interpolation...")
        print(f"Interpolation range: [{x_interp.min():.3f}, {x_interp.max():.3f}]")
        
        # Apply light denoising starting from these interpolated real images
        timesteps = [100, 80, 60, 40, 25, 15, 8, 3, 1]
        
        x = x_interp.clone()
        
        for t_val in timesteps:
            t_tensor = torch.full((4,), t_val, device=device, dtype=torch.long)
            
            # Get model prediction
            predicted_noise = model(x, t_tensor)
            
            # Apply denoising step
            alpha_bar_t = noise_scheduler.alpha_bars[t_val].item()
            x = (x - np.sqrt(1 - alpha_bar_t) * predicted_noise * 0.3) / np.sqrt(alpha_bar_t)  # Gentle denoising
            x = torch.clamp(x, -1, 1)
        
        print(f"Interpolation result range: [{x.min():.3f}, {x.max():.3f}]")
        
        # Save interpolation result
        interp_display = torch.clamp((x + 1) / 2, 0, 1)
        interp_grid = make_grid(interp_display, nrow=2, normalize=False)
        save_image(interp_grid, "interpolation_sampling.png")
        print("Interpolation sampling saved to interpolation_sampling.png")
        
        print("\n=== TRYING MINIMAL NOISE SAMPLING ===")
        
        # Start from very light noise around zero
        x_minimal = torch.randn(4, 3, 64, 64, device=device) * 0.1  # Very light noise
        
        # Apply just a few denoising steps
        light_timesteps = [50, 30, 15, 5, 1]
        
        for t_val in light_timesteps:
            t_tensor = torch.full((4,), t_val, device=device, dtype=torch.long)
            
            # Get model prediction
            predicted_noise = model(x_minimal, t_tensor)
            
            # Light denoising
            alpha_bar_t = noise_scheduler.alpha_bars[t_val].item()
            x_minimal = (x_minimal - np.sqrt(1 - alpha_bar_t) * predicted_noise * 0.5) / np.sqrt(alpha_bar_t)
            x_minimal = torch.clamp(x_minimal, -1, 1)
        
        print(f"Minimal noise result range: [{x_minimal.min():.3f}, {x_minimal.max():.3f}]")
        print(f"Minimal noise result std: {x_minimal.std():.3f}")
        
        # Save minimal noise result
        minimal_display = torch.clamp((x_minimal + 1) / 2, 0, 1)
        minimal_grid = make_grid(minimal_display, nrow=2, normalize=False)
        save_image(minimal_grid, "minimal_noise_sampling.png")
        print("Minimal noise sampling saved to minimal_noise_sampling.png")
        
        print("\n=== SUMMARY ===")
        print("Generated files:")
        print("- real_training_images.png (what we want to achieve)")
        print("- reconstruction_t*.png (model's denoising ability)")
        print("- interpolation_sampling.png (interpolation approach)")
        print("- minimal_noise_sampling.png (light noise approach)")

if __name__ == "__main__":
    diagnose_and_fix()