Supported Keras Operators

The Keras frontend supports Sequential() Keras models. The list of supported operations is as follows:

  • Conv2D

  • DepthwiseConv2D

  • Dense

  • BatchNormalization

  • MaxPooling2D

  • AveragePooling2D

  • Flatten

  • Add

  • ZeroPadding2D

  • Activation

    • relu

    • tanh

    • softmax

Limitations

  • Currently, we support Convolutional Neural Networks (CNNs) that include the supported operators (above) - RNNs/LSTMs not supported

  • We currently only support models in NCHW format (NHWC is not supported)

  • Softmax operator should be the last operation in the CNN pipeline

  • Softmax operation must be a separate operator (not specified as activation to another type of Keras operator). Example of what works:

Activation ("softmax")

Example of what is NOT supported:

Dense(num_classes, activation="softmax")

  • For convolutions with stride > 1 same convolution is NOT supported. Explicitly add ZeroPadding2D layer before Conv2D or DepthwiseConv2D operators. Example of what does NOT work:

Conv2D(num_filters, kernel_size=(3, 3), strides=(2, 2), padding="same")

Example of what works instead:

# NOTE: Amount of padding varies with kernel sizes and strides
ZeroPadding2D(padding=(1, 1), data_format="channels_first") # only support NCHW
Conv2D(num_filters, kernel_size=(3, 3), strides=(2, 2), padding="valid")