> For the complete documentation index, see [llms.txt](https://deeplearning4j.konduit.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://deeplearning4j.konduit.ai/model-import/overview-1/layers-pooling.md). # Pooling Layers ### Keras Pooling Layer Import Pooling layer support is implemented in the [layers/pooling](https://github.com/eclipse/deeplearning4j/tree/master/deeplearning4j/deeplearning4j-modelimport/src/main/java/org/deeplearning4j/nn/modelimport/keras/layers/pooling) package. All standard Keras pooling layers are supported. #### Support Summary | Keras Layer | DL4J Equivalent | Supported | | ---------------------- | ------------------------ | --------- | | MaxPooling1D | Subsampling1DLayer (MAX) | Yes | | MaxPooling2D | SubsamplingLayer (MAX) | Yes | | MaxPooling3D | Subsampling3DLayer (MAX) | Yes | | AveragePooling1D | Subsampling1DLayer (AVG) | Yes | | AveragePooling2D | SubsamplingLayer (AVG) | Yes | | AveragePooling3D | Subsampling3DLayer (AVG) | Yes | | GlobalMaxPooling1D | GlobalPoolingLayer (MAX) | Yes | | GlobalMaxPooling2D | GlobalPoolingLayer (MAX) | Yes | | GlobalMaxPooling3D | GlobalPoolingLayer (MAX) | Yes | | GlobalAveragePooling1D | GlobalPoolingLayer (AVG) | Yes | | GlobalAveragePooling2D | GlobalPoolingLayer (AVG) | Yes | | GlobalAveragePooling3D | GlobalPoolingLayer (AVG) | Yes | *** ### KerasPooling1D [source](https://github.com/eclipse/deeplearning4j/tree/master/deeplearning4j/deeplearning4j-modelimport/src/main/java/org/deeplearning4j/nn/modelimport/keras/layers/pooling/KerasPooling1D.java) Imports a Keras 1D pooling layer (`MaxPooling1D` or `AveragePooling1D`) as a DL4J `Subsampling1DLayer`. #### Constructor ```java public KerasPooling1D(Map layerConfig) throws InvalidKerasConfigurationException, UnsupportedKerasConfigurationException ``` **Parameters:** * `layerConfig` — dictionary containing the Keras layer configuration #### getSubsampling1DLayer ```java public Subsampling1DLayer getSubsampling1DLayer() ``` Returns the DL4J `Subsampling1DLayer`. The pooling type (MAX or AVG) is inferred from the Keras class name. #### getOutputType ```java public InputType getOutputType(InputType... inputType) throws InvalidKerasConfigurationException ``` *** ### KerasPooling2D [source](https://github.com/eclipse/deeplearning4j/tree/master/deeplearning4j/deeplearning4j-modelimport/src/main/java/org/deeplearning4j/nn/modelimport/keras/layers/pooling/KerasPooling2D.java) Imports a Keras 2D pooling layer (`MaxPooling2D` or `AveragePooling2D`) as a DL4J `SubsamplingLayer`. #### Constructor ```java public KerasPooling2D(Map layerConfig) throws InvalidKerasConfigurationException, UnsupportedKerasConfigurationException ``` #### getSubsampling2DLayer ```java public SubsamplingLayer getSubsampling2DLayer() ``` Returns the DL4J `SubsamplingLayer`. #### getOutputType ```java public InputType getOutputType(InputType... inputType) throws InvalidKerasConfigurationException ``` *** ### KerasPooling3D [source](https://github.com/eclipse/deeplearning4j/tree/master/deeplearning4j/deeplearning4j-modelimport/src/main/java/org/deeplearning4j/nn/modelimport/keras/layers/pooling/KerasPooling3D.java) Imports a Keras 3D pooling layer (`MaxPooling3D` or `AveragePooling3D`) as a DL4J `Subsampling3DLayer`. #### Constructor ```java public KerasPooling3D(Map layerConfig) throws InvalidKerasConfigurationException, UnsupportedKerasConfigurationException ``` #### getSubsampling3DLayer ```java public Subsampling3DLayer getSubsampling3DLayer() ``` *** ### KerasGlobalPooling [source](https://github.com/eclipse/deeplearning4j/tree/master/deeplearning4j/deeplearning4j-modelimport/src/main/java/org/deeplearning4j/nn/modelimport/keras/layers/pooling/KerasGlobalPooling.java) Imports any Keras global pooling layer (GlobalMaxPooling1D/2D/3D, GlobalAveragePooling1D/2D/3D) as a DL4J `GlobalPoolingLayer`. #### Constructor ```java public KerasGlobalPooling(Map layerConfig) throws InvalidKerasConfigurationException, UnsupportedKerasConfigurationException ``` #### getGlobalPoolingLayer ```java public GlobalPoolingLayer getGlobalPoolingLayer() ``` Returns the DL4J `GlobalPoolingLayer`. Pooling type and dimensionality are inferred from the Keras class name. #### getInputPreprocessor ```java public InputPreProcessor getInputPreprocessor(InputType... inputType) throws InvalidKerasConfigurationException ``` Returns the appropriate `InputPreProcessor` when the global pooling layer follows a layer with a different output format (e.g., following a convolutional layer). #### getOutputType ```java public InputType getOutputType(InputType... inputType) throws InvalidKerasConfigurationException ``` *** ### KerasPoolingUtils [source](https://github.com/eclipse/deeplearning4j/tree/master/deeplearning4j/deeplearning4j-modelimport/src/main/java/org/deeplearning4j/nn/modelimport/keras/layers/pooling/KerasPoolingUtils.java) Utility class for pooling layer import. #### mapPoolingType ```java public static PoolingType mapPoolingType(String className, KerasLayerConfiguration conf) throws UnsupportedKerasConfigurationException ``` Maps a Keras pooling class name (e.g., `"MaxPooling2D"`) to the corresponding DL4J `PoolingType` enum value (`PoolingType.MAX` or `PoolingType.AVG`). **Parameters:** * `className` — the Keras layer class name string * `conf` — the `KerasLayerConfiguration` instance **Returns:** DL4J `PoolingType` *** ### Notes * All pooling layers use the `pool_size`, `strides`, and `padding` parameters from the Keras configuration. * The `padding` value `"same"` and `"valid"` are both supported and translated to the equivalent DL4J padding modes. * Global pooling layers collapse the spatial dimensions entirely; DL4J's `GlobalPoolingLayer` handles all three dimensionalities via the same class, parameterized by `PoolingDimensions`.