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This package shows how to train a siamese network using Lasagne and Theano and includes network definitions for state-of-the-art networks including: DeepID, DeepID2, Chopra et. al, and Hani et. al. We also include one pre-trained model using a custom convolutional network.

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Siamese Net



The siamese network is a method for training a distance function discriminatively. Its use is popularized in many facial verification models including ones developed by Facebook and Google. The basic idea is to run a deep net on pairs of images describing either matched or unmatched pairs. The same network is run separately for the left and right images, but the loss is computed on the pairs of images rather than a single image. This is done by making use of the "batch" dimension of the input tensor, and computing loss on interleaved batches. If the left image is always the even idx (0, 2, 4, ...) and the right image is always the odd idxs, (1, 3, 5, ...), then the loss is computed on the alternating batches:

loss = output[::2] - output[1::2]
, for instance. By feeding in pairs of images that are either true or false pairs, the output of the networks should try to push similar matching pairs closer to together, while keeping unmatched pairs farther away.

This package shows how to train a siamese network using Lasagne and Theano and includes network definitions for state-of-the-art networks including: DeepID, DeepID2, Chopra et. al, and Hani et. al. We also include one pre-trained model using a custom convolutional network.

We are releasing all of this to the community in the hopes that it will encourage more models to be shared and appropriated for other possible uses. The framework we share here should allow one to train their own network, compute results, and visualize the results. We encourage the community to explore its use, submit pull requests on any issues within the package, and to contribute pre-trained models.



Siamese Network for performing training of a Deep Convolutional Network for Face Verification on the Olivetti and LFW Faces datasets.


python 3.4+, numpy>=1.10.4, sklearn>=0.17, scipy>=0.17.0, theano>=0.7.0, lasagne>=0.1, cv2, dlib>=18.18 (only required if using the 'trees' crop mode).

Part of the package siamesenet: siamesenet/ siamesenet/ siamesenet/ siamesenet/ siamesenet/

Look at the notebook file

for how to use the pre-trained model to predict pairs of images or visualize layers of the model.

images/layers.png images/gradient.png

Also look at
for training your own model. The default parameters will train a model on LFW without any face localization.
$ python3 --help
usage: [-h] [-m MODEL_TYPE] [-of N_OUT] [-bs BATCH_SIZE]
                      [-e N_EPOCHS] [-lr LEARNING_RATE] [-dp DROPOUT_PCT]
                      [-norm NORMALIZATION] [-f FILENAME] [-path PATH_TO_DATA]
                      [-hm HYPERPARAMETER_MARGIN]
                      [-ht HYPERPARAMETER_THRESHOLD] [-ds DATASET]
                      [-nl NONLINEARITY] [-fn DISTANCE_FN] [-cf CROP_FACTOR]
                      [-sp SPATIAL] [-r RESOLUTION] [-nf NUM_FILES]
                      [-gray B_CONVERT_TO_GRAYSCALE]

optional arguments: -h, --help show this help message and exit -m MODEL_TYPE, --model_type MODEL_TYPE Choose the Deep Network to use. ["hani"], "chopra", or "custom" (default: hani) -of N_OUT, --output_features N_OUT Number of features in the final siamese network layer (default: 40) -bs BATCH_SIZE, --batch_size BATCH_SIZE Number of observations per batch. (default: 100) -e N_EPOCHS, --epochs N_EPOCHS Number of epochs to train for. (default: 5) -lr LEARNING_RATE, --learning_rate LEARNING_RATE Initial learning rate to apply to the gradient update. (default: 0.0001) -dp DROPOUT_PCT, --dropout_pct DROPOUT_PCT Percentage of connections to drop in between Convolutional layers. (default: 0.0) -norm NORMALIZATION, --normalization NORMALIZATION Normalization of the dataset using either ["-1:1"], "LCN", "LCN-", or "ZCA". (default: -1:1) -f FILENAME, --filename FILENAME Resulting pickle file to store results. If none is given, a filename is created based on the combination of all parameters. (default: None) -path PATH_TO_DATA, --path_to_data PATH_TO_DATA Path to the dataset. If none is given it is assumed to be in the current working directory (default: None) -hm HYPERPARAMETER_MARGIN, --hyperparameter_margin HYPERPARAMETER_MARGIN Contrastive Loss parameter describing the total free energy. (default: 2.0) -ht HYPERPARAMETER_THRESHOLD, --hyperparameter_threshold HYPERPARAMETER_THRESHOLD Threshold to apply to the difference in the final output layer. (default: 5.0) -ds DATASET, --dataset DATASET The dataset to train/test with. Choose from ["lfw"], or "olivetti" (default: lfw) -nl NONLINEARITY, --nonlinearity NONLINEARITY Non-linearity to apply to convolution layers. (default: rectify) -fn DISTANCE_FN, --distance_fn DISTANCE_FN Distance function to apply to final siamese layer. (default: l2) -cf CROP_FACTOR, --cropfactor CROP_FACTOR Scale factor of amount of image around the face to use. (default: 1.0) -sp SPATIAL, --spatial_transform SPATIAL Whether or not to prepend a spatial transform network (default: False) -r RESOLUTION, --resolution RESOLUTION Rescale images to this fixed square pixel resolution (e.g. 64 will mean images, after any crops, are rescaled to 64 x 64). (default: 64) -nf NUM_FILES, --num_files NUM_FILES Number of files to load for each person. (default: 2) -gray B_CONVERT_TO_GRAYSCALE, --grayscale B_CONVERT_TO_GRAYSCALE Convert images to grayscale. (default: True)

Example output of training w/ default parameters:

$ python3
Namespace(b_convert_to_grayscale=True, batch_size=100, crop_factor=1.0, dataset='lfw', distance_fn='l2', dropout_pct=0.0, filename=None, hyperparameter_margin=2.0, hyperparameter_threshold=5.0, learning_rate=0.0001, model_type='hani', n_epochs=5, n_out=40, nonlinearity='rectify', normalization='-1:1', num_files=2, path_to_data=None, resolution=64, spatial=False)
Dataset: lfw
Spatial: 0
Batch Size: 100
Num Features: 40
Model Type: hani
Num Epochs: 5
Num Files: 2
Learning Rate: 0.000100
Normalization: -1:1
Crop Factor: 1
Resolution: 64
Hyperparameter Margin: 2.000000
Hyperparameter Threshold: 5.000000
Dropout Percent: 0.000000
Non-Linearity: rectify
Grayscale: 1
Distance Function: l2

Writing results to: results/dataset_lfw_transform_0_batch_100_lr_0.000100_model_hani_epochs_5_normalization_-1:1_cropfactor_1.00_nout_40_resolution_64_numfiles_2_q_2.00_t_5.00_d_0.00_nonlinearity_rectify_distancefn_l2_grayscale_1.pkl

Loading dataset... Preprocessing dataset Loading data in siamese-net/lfw Person: 5749/5749 (11498, 1, 64, 64) Initializing Siamese Network... (11498, 1, 64, 64)

Epoch 1 of 5 took 20.952s training loss: 0.008983 validation loss: 0.007918 validation AUC: 0.64 validation F1: 0.69

... training will begin after downloading the dataset, pre-processing faces, and compilation (can take ~30 minutes!). Each epoch will then take ~ 21 seconds using these default parameters using a GeForce GT 750M GPU.


Chopra, S., Hadsell, R., & Y., L. (2005). Learning a similiarty metric discriminatively, with application to face verification. Proceedings of IEEE Conference on Computer Vision and Pattern Recognition, 349–356.

Donahue, J., Jia, Y., Vinyals, O., Hoffman, J., Zhang, N., Tzeng, E., & Darrell, T. (2014). DeCAF: A Deep Convolutional Activation Feature for Generic Visual Recognition. arXiv Preprint. Retrieved from

El-bakry, H. M., & Zhao, Q. (2005). Fast Object / Face Detection Using Neural Networks and Fast Fourier Transform, 8580(11), 503–508.

Huang, G. B., Mattar, M. a., Lee, H., & Learned-Miller, E. (2012). Learning to Align from Scratch. Proc. Neural Information Processing Systems, 1–9.

Khalil-Hani, M., & Sung, L. S. (2014). A convolutional neural network approach for face verification. High Performance Computing & Simulation (HPCS), 2014 International Conference on, (3), 707–714. doi:10.1109/HPCSim.2014.6903759

Kostinger, M., Hirzer, M., Wohlhart, P., Roth, P. M., & Bischof, H. (2012). Large scale metric learning from equivalence constraints. Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition, (Ldml), 2288–2295. doi:10.1109/CVPR.2012.6247939

Li, H., & Hua, G. (2015). Hierarchical-PEP Model for Real-world Face Recognition, 4055–4064. doi:10.1109/CVPR.2015.7299032

Parkhi, O. M., Vedaldi, A., Zisserman, A., Vedaldi, A., Lenc, K., Jaderberg, M., … others. (2015). Deep face recognition. Proceedings of the British Machine Vision, (Section 3).

Sun, Y., Wang, X., & Tang, X. (2014). Deep Learning Face Representation by Joint Identification-Verification. Nips, 1–9. doi:10.1109/CVPR.2014.244

Taigman, Y., Yang, M., Ranzato, M., & Wolf, L. (2014). DeepFace: Closing the Gap to Human-Level Performance in Face Verification. Conference on Computer Vision and Pattern Recognition (CVPR), 8. doi:10.1109/CVPR.2014.220

Wheeler, F. W., Liu, X., & Tu, P. H. (2007). Multi-Frame Super-Resolution for Face Recognition. 2007 First IEEE International Conference on Biometrics: Theory, Applications, and Systems, 1–6. doi:10.1109/BTAS.2007.4401949

Yi, D., Lei, Z., Liao, S., & Li, S. Z. (2014). Learning Face Representation from Scratch. arXiv.


Parag K. Mital Copyright 2016 Kadenze, Inc. Kadenze(R) and Kannu(R) are Registered Trademarks of Kadenze, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Apache License

Version 2.0, January 2004


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