app.py

import gradio as gr
import torch
from torchvision import transforms
from PIL import Image

# Import your model class from the model.py file
from model import SimpleCNN

# --- 1. SETUP ---
# Define the path to your model and the number of classes
MODEL_PATH = "air_analyzer_cnn_iden_7m.pth" # Make sure this file is in your repository
NUM_CLASSES = 3
# Define your class names
class_names = ["Cat", "Dog", "Bird"]

# --- 2. LOAD THE MODEL ---
# Instantiate the model (must be the same architecture as the one you saved)
model = SimpleCNN(num_classes=NUM_CLASSES)

# Load the trained weights
# Use map_location=torch.device('cpu') to ensure the model runs on the CPU
# This is crucial for Hugging Face Spaces' free tier
model.load_state_dict(torch.load(MODEL_PATH, map_location=torch.device('cpu')))

# Set the model to evaluation mode
model.eval()

# --- 3. DEFINE IMAGE TRANSFORMATIONS ---
# This should be the same transformation as used during training/validation
transform = transforms.Compose([
    transforms.Resize((224, 224)), # Resize the image to 224x224 pixels
    transforms.ToTensor(),         # Convert the image to a PyTorch tensor
    transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225]) # Normalize
])

# --- 4. DEFINE THE PREDICTION FUNCTION ---
def predict(input_image: Image.Image):
    """
    Takes a PIL image, processes it, and returns a dictionary of class probabilities.
    """
    # Apply the transformations to the input image
    image_tensor = transform(input_image).unsqueeze(0) # Add a batch dimension

    # Make a prediction
    with torch.no_grad(): # Disable gradient calculation for inference
        outputs = model(image_tensor)
        
    # Apply softmax to get probabilities
    probabilities = torch.nn.functional.softmax(outputs[0], dim=0)
    
    # Create a dictionary of class names and their probabilities
    confidences = {class_names[i]: float(prob) for i, prob in enumerate(probabilities)}
    
    return confidences

# --- 5. CREATE THE GRADIO INTERFACE ---
# Define the input and output components
image_input = gr.Image(type="pil", label="Upload an Image")
label_output = gr.Label(num_top_classes=3, label="Predictions")

# Example images (optional but highly recommended)
# Make sure you upload these images to your Space repository
example_images = [
    "sample_cat.jpg",
    "sample_dog.jpg",
    "sample_bird.jpg"
]

# Create and launch the interface
iface = gr.Interface(
    fn=predict,
    inputs=image_input,
    outputs=label_output,
    title="Image Classifier",
    description="Upload an image of a cat, dog, or bird to see the model's prediction.",
    examples=example_images
)

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