# instance_norm¶

api_attr

declarative programming (static graph)

paddle.fluid.layers.instance_norm(input, epsilon=1e-05, param_attr=None, bias_attr=None, name=None)[source]

Instance Normalization Layer

Can be used as a normalizer function for convolution or fully_connected operations. The required data format for this layer is one of the following:

DataLayout: NCHW [batch, in_channels, in_height, in_width]

Refer to Instance Normalization: The Missing Ingredient for Fast Stylization for more details.

$$input$$ is the input features over a mini-batch.

$\begin{split}\mu_{\beta} &\gets \frac{1}{HW} \sum_{i=1}^{HW} x_i \qquad &//\ \ mean\ of\ one\ feature\ map\ in\ mini-batch \\ \sigma_{\beta}^{2} &\gets \frac{1}{HW} \sum_{i=1}^{HW}(x_i - \ \mu_{\beta})^2 \qquad &//\ variance\ of\ one\ feature\ map\ in\ mini-batch \\ \hat{x_i} &\gets \frac{x_i - \mu_\beta} {\sqrt{\ \sigma_{\beta}^{2} + \epsilon}} \qquad &//\ normalize \\ y_i &\gets \gamma \hat{x_i} + \beta \qquad &//\ scale\ and\ shift\end{split}$

Note

H means height of feature map, W means width of feature map.

Parameters
• input (variable) – The rank of input variable can be 2, 3, 4, 5. The data type is float32 or float64.

• epsilon (float, Default 1e-05) – A value added to the denominator for numerical stability. Default is 1e-5.

• param_attr (ParamAttr|None) – The parameter attribute for Parameter scale of instance_norm. If it is set to None or one attribute of ParamAttr, instance_norm will create ParamAttr as param_attr, the name of scale can be set in ParamAttr. If the Initializer of the param_attr is not set, the parameter is initialized with Xavier. Default: None.

• bias_attr (ParamAttr|None) – The parameter attribute for the bias of instance_norm. If it is set to None or one attribute of ParamAttr, instance_norm will create ParamAttr as bias_attr, the name of bias can be set in ParamAttr. If the Initializer of the bias_attr is not set, the bias is initialized zero. Default: None.

• name (string, Default None) – A name for this layer(optional). If set None, the layer will be named automatically.

Returns

A Variable holding Tensor which is the result after applying instance normalization on the input, has same shape and data type with input.

Examples

import paddle.fluid as fluid
x = fluid.data(name='x', shape=[3, 7, 3, 7], dtype='float32')
hidden1 = fluid.layers.fc(input=x, size=200, param_attr='fc1.w')
hidden2 = fluid.layers.instance_norm(input=hidden1)