app.py

import gradio as gr
import torch
from torch import nn
from torchvision import models, transforms
from huggingface_hub import hf_hub_download
from PIL import Image
import os
import logging
import requests
from io import BytesIO
import numpy as np

# Setup logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Define the number of classes
num_classes = 3

# Confidence threshold for reliable predictions
CONFIDENCE_THRESHOLD = 0.8  # 80%

# Entropy threshold for flat probability distribution (to detect non-maize/rice images)
ENTROPY_THRESHOLD = 0.9  # Lower entropy means a more peaked distribution (more confident)

# Download model from Hugging Face
def download_model():
    model_path = hf_hub_download(repo_id="jays009/Resnet3", filename="model.pth")
    return model_path

# Load the model from Hugging Face
def load_model(model_path):
    model = models.resnet50(pretrained=False)
    num_features = model.fc.in_features
    model.fc = nn.Sequential(
        nn.Dropout(0.5),
        nn.Linear(num_features, num_classes)  # 3 classes
    )

    # Load the checkpoint
    checkpoint = torch.load(model_path, map_location=torch.device("cpu"))
    
    # Adjust for state dict mismatch by renaming keys
    state_dict = checkpoint['model_state_dict']
    new_state_dict = {}
    for k, v in state_dict.items():
        if k == "fc.weight" or k == "fc.bias":
            new_state_dict[f"fc.1.{k.split('.')[-1]}"] = v
        else:
            new_state_dict[k] = v

    model.load_state_dict(new_state_dict, strict=False)
    model.eval()
    return model

# Path to your model
model_path = download_model()
model = load_model(model_path)

# Define the transformation for the input image
transform = transforms.Compose([
    transforms.Resize(256),
    transforms.CenterCrop(224),
    transforms.ToTensor(),
    transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225]),
])

# Function to compute entropy of the probability distribution
def compute_entropy(probabilities):
    probs = probabilities.numpy()  # Convert to numpy array
    # Avoid log(0) by adding a small epsilon
    probs = np.clip(probs, 1e-10, 1.0)
    entropy = -np.sum(probs * np.log(probs))
    # Normalize entropy by the maximum possible entropy (log(num_classes))
    max_entropy = np.log(num_classes)
    return entropy / max_entropy

# Prediction function for an uploaded image
def predict_from_image_url(image_url):
    try:
        # Download the image from the provided URL
        response = requests.get(image_url)
        response.raise_for_status()
        image = Image.open(BytesIO(response.content)).convert("RGB")  # Convert to RGB (3 channels)

        # Apply transformations
        image_tensor = transform(image).unsqueeze(0)  # Shape: [1, 3, 224, 224]
        logger.info(f"Input image tensor shape: {image_tensor.shape}")

        # Perform prediction
        with torch.no_grad():
            outputs = model(image_tensor)  # Shape: [1, 3]
            logger.info(f"Model output shape: {outputs.shape}")
            probabilities = torch.softmax(outputs, dim=1)[0]  # Convert to probabilities
            predicted_class = torch.argmax(outputs, dim=1).item()

        # Define class information
        class_info = {
            0: {"name": "Fall Army Worm", "problem_id": "126", "crop": "maize"},
            1: {"name": "Phosphorus Deficiency", "problem_id": "142", "crop": "maize"},
            2: {"name": "Bacterial Leaf Blight", "problem_id": "203", "crop": "rice"}
        }

        # Validate predicted class index
        if predicted_class not in class_info:
            logger.warning(f"Unexpected class prediction: {predicted_class} for image URL: {image_url}")
            return {
                "status": "invalid",
                "predicted_class": None,
                "problem_id": None,
                "confidence": None
            }

        # Get predicted class info
        predicted_info = class_info[predicted_class]
        predicted_name = predicted_info["name"]
        problem_id = predicted_info["problem_id"]
        confidence = probabilities[predicted_class].item()  # Confidence score for the predicted class

        # Compute entropy of the probability distribution
        entropy = compute_entropy(probabilities)
        logger.info(f"Prediction entropy: {entropy:.4f}, confidence: {confidence:.4f} for image URL: {image_url}")

        # Check if the image is likely maize or rice based on entropy and confidence
        # High entropy (flat distribution) suggests the image may not be maize or rice
        if entropy > ENTROPY_THRESHOLD:
            logger.warning(
                f"High entropy ({entropy:.4f} > {ENTROPY_THRESHOLD}) for image URL: {image_url}. "
                "Image may not be of maize or rice."
            )
            return {
                "status": "invalid",
                "predicted_class": predicted_name,
                "problem_id": problem_id,
                "confidence": f"{confidence*100:.2f}%"
            }

        # Check confidence threshold
        if confidence < CONFIDENCE_THRESHOLD:
            logger.warning(
                f"Low confidence prediction: {predicted_name} with confidence {confidence*100:.2f}% "
                f"for image URL: {image_url}"
            )
            return {
                "status": "invalid",
                "predicted_class": predicted_name,
                "problem_id": problem_id,
                "confidence": f"{confidence*100:.2f}%"
            }

        # Return successful prediction
        return {
            "status": "valid",
            "predicted_class": predicted_name,
            "problem_id": problem_id,
            "confidence": f"{confidence*100:.2f}%"
        }

    except Exception as e:
        logger.error(f"Error processing image URL {image_url}: {str(e)}")
        return {
            "status": "invalid",
            "predicted_class": None,
            "problem_id": None,
            "confidence": None
        }

# Gradio interface
demo = gr.Interface(
    fn=predict_from_image_url,
    inputs="text",
    outputs="json",
    title="Crop Anomaly Classification",
    description="Enter a URL to an image for classification (Fall Army Worm, Phosphorus Deficiency, or Bacterial Leaf Blight).",
)

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