# MPSCNNSpatialNormalization A spatial normalization kernel. ``` class MPSCNNSpatialNormalization ``` ## Overview The spatial normalization for a feature channel applies the kernel over local regions which extend spatially, but are in separate feature channels (i.e., they have the shape `1 x kernel width x kernel height`). For each feature channel, the function computes the sum of squares of `X` inside each rectangle, `N2(i,j)`. It then divides each element of `X` as follows:  Where `kw` and `kh` are the values of the `kernelWidth` and `kernelHeight` properties, respectively. It is your responsibility to ensure that the combination of the values of the [`delta`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/delta) and [`alpha`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/alpha) `kernelWidth` `kernelHeight` properties does not result in a situation where the denominator becomes zero (in such situations the resulting pixel-value is undefined). > Note: > The encoding methods in the ``doc://com.apple.metalperformanceshaders/documentation/MetalPerformanceShaders/MPSUnaryImageKernel`` class can be used to encode an ``doc://com.apple.metalperformanceshaders/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization`` object to a object. ## Topics ### Initializers [`init(coder:device:)`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/init(coder:device:)) Initializes a spatial normalization kernel. [`init(device:kernelWidth:kernelHeight:)`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/init(device:kernelWidth:kernelHeight:)) Initializes a spatial normalization kernel. ### Instance Properties [`alpha`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/alpha) The “alpha” variable of the kernel function. [`beta`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/beta) The “beta” variable of the kernel function. [`delta`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/delta) The “delta” variable of the kernel function. ### Instance Methods [`init(device:kernelWidth:kernelHeight:)`](/documentation/MetalPerformanceShaders/MPSCNNSpatialNormalization/init(device:kernelWidth:kernelHeight:)) Initializes a spatial normalization kernel. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)