app.py

import numpy as np
import tensorflow as tf
from tensorflow import keras
from keras.layers import Input , Lambda , Dense , Flatten , Rescaling
from keras.models import Model
import gradio as gr
# Display
from IPython.display import Image, display
import matplotlib.pyplot as plt
import matplotlib.cm as cm


##### Configureable variabels ###########
model_weights_path = "./model_weights.h5"

####################################################################
############       Creating new model  #############################
####################################################################
base_model = keras.applications.Xception(input_shape=(160,160,3) , include_top=False)
base_model.trainable = False

def create_model():
  input_layer = keras.Input(shape=(160,160,3))
  R1 = Rescaling(scale=1/255)(input_layer)
  B = base_model(R1 , training=False)
  P1 = keras.layers.GlobalAveragePooling2D()(B)
  output_layer = Dense(1 , activation="sigmoid")(P1)
  model = keras.Model(input_layer , output_layer)
  model.compile(optimizer=keras.optimizers.Adam(0.001) , loss=keras.losses.BinaryCrossentropy() , metrics=["accuracy"])
  return model , input_layer, R1 , B , P1 , output_layer
  
print("Creating new model ...")
model , input_layer , R1 , B , P1 , output_layer = create_model()
print("Loading weights ....")
model.load_weights(model_weights_path)

####################################################################
############     Creating gradcam model    #########################
####################################################################
def make_gradcam_heatmap(img_array, model):

    # we compute the gradient of the top predicted class for our input image
    # with respect to the activations of the last conv layer
    preds = None
    with tf.GradientTape() as tape:
        preds , last_conv_layer_output = grad_model(img_array)

    # This is the gradient of the output neuron (top predicted or chosen)
    # with regard to the output feature map of the last conv layer
    grads = tape.gradient(preds, last_conv_layer_output)

    # This is a vector where each entry is the mean intensity of the gradient
    # over a specific feature map channel
    pooled_grads = tf.reduce_mean(grads, axis=(0, 1, 2))

    # We multiply each channel in the feature map array
    # by "how important this channel is" with regard to the top predicted class
    # then sum all the channels to obtain the heatmap class activation
    last_conv_layer_output = last_conv_layer_output[0]
    heatmap = last_conv_layer_output @ pooled_grads[..., tf.newaxis]
    heatmap = tf.squeeze(heatmap)

    # For visualization purpose, we will also normalize the heatmap between 0 & 1
    heatmap = tf.maximum(heatmap, 0) / tf.math.reduce_max(heatmap)
    return preds , heatmap.numpy()
	
def get_gradcam(img, heatmap , alpha=0.4):

    # Rescale heatmap to a range 0-255
    heatmap = np.uint8(255 * heatmap)

    # Use jet colormap to colorize heatmap
    jet = cm.get_cmap("jet")

    # Use RGB values of the colormap
    jet_colors = jet(np.arange(256))[:, :3]
    jet_heatmap = jet_colors[heatmap]

    # Create an image with RGB colorized heatmap
    jet_heatmap = keras.utils.array_to_img(jet_heatmap)
    jet_heatmap = jet_heatmap.resize((img.shape[1], img.shape[0]))
    jet_heatmap = keras.utils.img_to_array(jet_heatmap)

    # Superimpose the heatmap on original image
    superimposed_img = jet_heatmap * alpha + img
    superimposed_img = keras.utils.array_to_img(superimposed_img)

    return superimposed_img

print("Creating Gradcam model ....")
grad_model = keras.Model(
        input_layer , [output_layer , B]
    )
grad_model.layers[-1].activation = None
grad_model.summary()

######################################################
def sigmoid(x):
    return 1 / (1 + np.exp(-x))
#######################################################
def predict_image(image):

    try:
      pred , heatmap = make_gradcam_heatmap(image.reshape((1, 160, 160, 3)) , grad_model)
      gradcam_image = get_gradcam(image , heatmap)

      pred = sigmoid(pred)
      predicted_label = f"{(1-pred[0][0])*100:.2f}% Dog \n{pred[0][0]*100:.2f}% Cat \nFinal Prediction : {'Dog' if pred[0][0] < 0.5 else 'Cat'}"
      
      # Return the predicted label
      return predicted_label , gradcam_image
    except Exception as error:
      return str(error)


image_input = gr.inputs.Image(shape=(160,160))
label_output = gr.outputs.Textbox(label="Prediction")
image_output = gr.outputs.Image(type="pil" , label="Heatmap")

# Create the Gradio interface
gr.Interface(fn=predict_image, inputs=image_input, outputs=[label_output , image_output]).launch()