app.py

import gradio as gr
import numpy as np
from huggingface_hub import from_pretrained_keras


def loss(margin=1):
    """Provides 'constrastive_loss' an enclosing scope with variable 'margin'.

    Arguments:
        margin: Integer, defines the baseline for distance for which pairs
                should be classified as dissimilar. - (default is 1).

    Returns:
        'constrastive_loss' function with data ('margin') attached.
    """

    # Contrastive loss = mean( (1-true_value) * square(prediction) +
    #                         true_value * square( max(margin-prediction, 0) ))
    def contrastive_loss(y_true, y_pred):
        """Calculates the constrastive loss.

      Arguments:
          y_true: List of labels, each label is of type float32.
          y_pred: List of predictions of same length as of y_true,
                  each label is of type float32.

      Returns:
          A tensor containing constrastive loss as floating point value.
      """

        square_pred = tf.math.square(y_pred)
        margin_square = tf.math.square(tf.math.maximum(margin - (y_pred), 0))
        return tf.math.reduce_mean(
            (1 - y_true) * square_pred + (y_true) * margin_square
        )

    return contrastive_loss

siamese = from_pretrained_keras("keras-io/siamese-contrastive",  custom_objects={"contrastive_loss": loss})

def predict_image(img1, img2):
  assert img1.shape == (28, 28)
  assert img1.shape == img2.shape
  print('img 1 shape', img1.shape)
  img1 = np.expand_dims(img1, 0)
  img2 = np.expand_dims(img2, 0)
  lab = str(siamese.predict([img1, img2])[0][0])
  return lab
  
title = "Image similarity estimation using a Siamese Network with a contrastive loss"
description = "This space implements a siamese network to compare similar images of the MNIST dataset. To use it simply draw two numbers in the input boxes."
article = """<p style='text-align: center'>
        <a href='https://keras.io/examples/vision/siamese_contrastive/' target='_blank'>Keras Example given by Mehdi</a>
        <br>
        Space by @rushic24
    </p>
    """

iface = gr.Interface(predict_image, inputs=["sketchpad", "sketchpad"], outputs="label", title=title, description=description, article=article)
iface.launch(debug='True')