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maxPooling3dLayer

3-D max pooling layer

Description

A 3-D max pooling layer performs downsampling by dividing three-dimensional input into cuboidal pooling regions, then computing the maximum of each region.

The dimensions that the layer pools over depends on the layer input:

  • For 3-D image input (data with five dimensions corresponding to pixels in three spatial dimensions, the channels, and the observations), the layer pools over the spatial dimensions.

  • For 3-D image sequence input (data with six dimensions corresponding to the pixels in three spatial dimensions, the channels, the observations, and the time steps), the layer pools over the spatial dimensions.

  • For 2-D image sequence input (data with five dimensions corresponding to the pixels in two spatial dimensions, the channels, the observations, and the time steps), the layer pools over the spatial and time dimensions.

Creation

Description

layer= maxPooling3dLayer(poolSize)creates a 3-D max pooling layer and sets thePoolSize财产.

example

layer= maxPooling3dLayer(poolSize,Name,Value)sets the optionalStrideandNameproperties using name-value pairs. To specify input padding, use the'Padding'name-value pair argument. For example,maxPooling3dLayer(2,'Stride',3)creates a 3-D max pooling layer with pool size[2 2 2]and stride[3 3 3]. You can specify multiple name-value pairs. Enclose each property name in single quotes.

Input Arguments

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Name-Value Arguments

Specify optional pairs of arguments asName1=Value1,...,NameN=ValueN, whereNameis the argument name andValueis the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and encloseNamein quotes.

Example:maxPooling3dLayer(2,'Stride',3)creates a 3-D max pooling layer with pool size[2 2 2]and stride[3 3 3].

Input edge padding, specified as the comma-separated pair consisting of'Padding'and one of these values:

  • 'same'— Add padding of size calculated by the software at training or prediction time so that the output has the same size as the input when the stride equals 1.If the stride is larger than 1, then the output size isceil(inputSize/stride), whereinputSizeis the height, width, or depth of the input andis the stride in the corresponding dimension. The software adds the same amount of padding to the top and bottom, to the left and right, and to the front and back, if possible. If the padding in a given dimension has an odd value, then the software adds the extra padding to the input as postpadding. In other words, the software adds extra vertical padding to the bottom, extra horizontal padding to the right, and extra depth padding to the back of the input.

  • Nonnegative integerp— Add padding of sizepto all the edges of the input.

  • Three-element vector[a b c]of nonnegative integers — Add padding of sizeato the top and bottom, padding of sizebto the left and right, and padding of sizecto the front and back of the input.

  • 2-by-3 matrix[t l f;b r k]of nonnegative integers — Add padding of sizetto the top,bto the bottom,lto the left,rto the right,fto the front, andkto the back of the input. In other words, the top row specifies the prepadding and the second row defines the postpadding in the three dimensions.

Example:'Padding',1adds one row of padding to the top and bottom, one column of padding to the left and right, and one plane of padding to the front and back of the input.

Example:'Padding','same'adds padding so that the output has the same size as the input (if the stride equals 1).

Properties

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Max Pooling

Dimensions of the pooling regions, specified as a vector of three positive integers[h w d], wherehis the height,wis the width, anddis the depth. When creating the layer, you can specifyPoolSizeas a scalar to use the same value for all three dimensions.

If the stride dimensionsStrideare less than the respective pooling dimensions, then the pooling regions overlap.

The padding dimensionsPaddingSizemust be less than the pooling region dimensionsPoolSize.

Example:[2 1 1]specifies pooling regions of height 2, width 1, and depth 1.

Step size for traversing the input in three dimensions, specified as a vector[a b c]of three positive integers, whereais the vertical step size,bis the horizontal step size, andcis the step size along the depth direction. When creating the layer, you can specifyStride作为标量一步大小我使用相同的值n all three directions.

If the stride dimensionsStrideare less than the respective pooling dimensions, then the pooling regions overlap.

The padding dimensionsPaddingSizemust be less than the pooling region dimensionsPoolSize.

Example:[2 3 1]specifies a vertical step size of 2, a horizontal step size of 3, and a step size along the depth of 1.

Size of padding to apply to input borders, specified as 2-by-3 matrix[t l f;b r k]of nonnegative integers, wheretandbare the padding applied to the top and bottom in the vertical direction,landrare the padding applied to the left and right in the horizontal direction, andfandkare the padding applied to the front and back along the depth. In other words, the top row specifies the prepadding and the second row defines the postpadding in the three dimensions.

When you create a layer, use the'Padding'name-value pair argument to specify the padding size.

Example:[1 2 4;1 2 4]adds one row of padding to the top and bottom, two columns of padding to the left and right, and four planes of padding to the front and back of the input.

Method to determine padding size, specified as'manual'or'same'.

The software automatically sets the value ofPaddingModebased on the 'Padding' value you specify when creating a layer.

  • If you set the'Padding'option to a scalar or a vector of nonnegative integers, then the software automatically setsPaddingModeto'manual'.

  • If you set the'Padding'option to'same', then the software automatically setsPaddingModeto'same'and calculates the size of the padding at training time so that the output has the same size as the input when the stride equals 1.If the stride is larger than 1, then the output size isceil(inputSize/stride), whereinputSizeis the height, width, or depth of the input andis the stride in the corresponding dimension. The software adds the same amount of padding to the top and bottom, to the left and right, and to the front and back, if possible. If the padding in a given dimension has an odd value, then the software adds the extra padding to the input as postpadding. In other words, the software adds extra vertical padding to the bottom, extra horizontal padding to the right, and extra depth padding to the back of the input.

Layer

Layer name, specified as a character vector or a string scalar. ForLayerarray input, thetrainNetwork,assembleNetwork,layerGraph, anddlnetworkfunctions automatically assign names to layers with name''.

Data Types:char|string

This property is read-only.

Number of inputs of the layer. This layer accepts a single input only.

Data Types:double

This property is read-only.

Input names of the layer. This layer accepts a single input only.

Data Types:cell

This property is read-only.

Number of outputs of the layer. This layer has a single output only.

Data Types:double

This property is read-only.

Output names of the layer. This layer has a single output only.

Data Types:cell

Examples

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Create a max pooling 3-D layer with nonoverlapping pooling regions.

layer = maxPooling3dLayer(2,'Stride',2)
layer = MaxPooling3DLayer with properties: Name: '' NumOutputs: 1 OutputNames: {'out'} Hyperparameters PoolSize: [2 2 2] Stride: [2 2 2] PaddingMode: 'manual' PaddingSize: [2x3 double]

The height, width, and depth of the cuboidal regions (pool size) are 2. The step size for traversing the images (stride) is 2 in all dimensions. The pooling regions do not overlap because the stride is greater than or equal to the corresponding pool size in all dimensions.

包括一个马克斯池层不重叠的再保险gions in aLayerarray.

layers = [...image3dInputLayer([28 28 28 3]) convolution3dLayer(5,20) reluLayer maxPooling3dLayer(2,'Stride',2) fullyConnectedLayer(10) softmaxLayer classificationLayer]
layers = 7x1 Layer array with layers: 1 '' 3-D Image Input 28x28x28x3 images with 'zerocenter' normalization 2 '' Convolution 20 5x5x5 convolutions with stride [1 1 1] and padding [0 0 0; 0 0 0] 3 '' ReLU ReLU 4 '' 3-D Max Pooling 2x2x2 max pooling with stride [2 2 2] and padding [0 0 0; 0 0 0] 5 '' Fully Connected 10 fully connected layer 6 '' Softmax softmax 7 '' Classification Output crossentropyex

Create a max pooling 3-D layer with overlapping pooling regions and padding for the top and bottom of the input.

layer = maxPooling3dLayer([3 2 2],'Stride',2,'Padding',[1 0 0])
layer = MaxPooling3DLayer with properties: Name: '' NumOutputs: 1 OutputNames: {'out'} Hyperparameters PoolSize: [3 2 2] Stride: [2 2 2] PaddingMode: 'manual' PaddingSize: [2x3 double]

This layer creates pooling regions of size 3-by-2-by-2 and takes the maximum of the twelve elements in each region. The stride is 2 in all dimensions. The pooling regions overlap because there are stride dimensionsStridethat are less than the respective pooling dimensionsPoolSize.

Algorithms

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版本历史

Introduced in R2019a