app/Hackathon_setup/exp_recognition.py

import numpy as np
import cv2
from matplotlib import pyplot as plt
import torch
# In the below line,remove '.' while working on your local system.However Make sure that '.' is present before face_recognition_model while uploading to the server, Do not remove it.
from .exp_recognition_model import *
from PIL import Image
import base64
import io
import os
## Add more imports if required

#############################################################################################################################
#   Caution: Don't change any of the filenames, function names and definitions                                              #
#   Always use the current_path + file_name for refering any files, without it we cannot access files on the server         #
#############################################################################################################################

# Current_path stores absolute path of the file from where it runs.
current_path = os.path.dirname(os.path.abspath(__file__))


#1) The below function is used to detect faces in the given image.
#2) It returns only one image which has maximum area out of all the detected faces in the photo.
#3) If no face is detected,then it returns zero(0).

def detected_face(image):
    eye_haar = current_path + '/haarcascade_eye.xml'
    face_haar = current_path + '/haarcascade_frontalface_default.xml'
    face_cascade = cv2.CascadeClassifier(face_haar)
    eye_cascade = cv2.CascadeClassifier(eye_haar)
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    faces = face_cascade.detectMultiScale(gray, 1.3, 5)
    face_areas=[]
    images = []
    required_image = None
    
    if len(faces) == 0:
        return None
        
    for i, (x,y,w,h) in enumerate(faces):
        face_cropped = gray[y:y+h, x:x+w]
        face_areas.append(w*h)
        images.append(face_cropped)
    
    if face_areas:
        max_area_idx = np.argmax(face_areas)
        required_image = images[max_area_idx]
        required_image = Image.fromarray(required_image)
        return required_image
    
    return None
    

#1) Images captured from mobile is passed as parameter to the below function in the API call, It returns the Expression detected by your network.
#2) The image is passed to the function in base64 encoding, Code for decoding the image is provided within the function.
#3) Define an object to your network here in the function and load the weight from the trained network, set it in evaluation mode.
#4) Perform necessary transformations to the input(detected face using the above function), this should return the Expression in string form ex: "Anger"
#5) For loading your model use the current_path+'your model file name', anyhow detailed example is given in comments to the function 
##Caution: Don't change the definition or function name; for loading the model use the current_path for path example is given in comments to the function
def get_expression(img):
    device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
    print(f"LOG: Using device: {device}")
    
    # Get face from image
    face = detected_face(img)
    if face is None:
        print("LOG: No face detected, using full image")
        face = Image.fromarray(cv2.cvtColor(img, cv2.COLOR_BGR2GRAY))
    else:
        print("LOG: Face detected successfully")
    
    try:
        # Load the Expression model
        model = ExpressionCNN(num_classes=7).to(device)
        model_path = current_path + '/expression_model.t7'
        print(f"LOG: Looking for model at: {model_path}")
        
        if os.path.exists(model_path):
            # Load model weights
            model.load_state_dict(torch.load(model_path, map_location=device))
            model.eval()
            print("LOG: Model loaded successfully")
            
            # Preprocess the face image
            face_tensor = trnscm(face).unsqueeze(0).to(device)
            print(f"LOG: Input tensor shape: {face_tensor.shape}")
            
            # Get prediction
            with torch.no_grad():
                outputs = model(face_tensor)
                _, predicted = torch.max(outputs.data, 1)
                predicted_class_idx = predicted.item()
                
                # Get prediction probabilities
                probabilities = torch.nn.functional.softmax(outputs, dim=1)[0]
                confidence = probabilities[predicted_class_idx].item() * 100
                
                # Convert index to class name
                expression = classes[predicted_class_idx]
                print(f"LOG: Predicted expression: {expression} with {confidence:.1f}% confidence")
                return expression
        else:
            print(f"ERROR: Model file not found: {model_path}")
            return "Unknown"
    except Exception as e:
        print(f"ERROR: Error in expression recognition: {str(e)}")
        import traceback
        traceback.print_exc()
        return "Unknown"