mojave man page for mpscnnspatialnormalizationgradient

MPSCNNSpatialNormalizationGradient(3)			 MetalPerformanceShaders.framework		     MPSCNNSpatialNormalizationGradient(3)

NAME
       MPSCNNSpatialNormalizationGradient

SYNOPSIS
       #import <MPSCNNNormalization.h>

       Inherits MPSCNNGradientKernel.

   Instance Methods
       (nonnull instancetype) - initWithDevice:kernelWidth:kernelHeight:
       (nullable instancetype) - initWithCoder:device:

   Properties
       float alpha
       float beta
       float delta
       NSUInteger kernelWidth
       NSUInteger kernelHeight

   Additional Inherited Members
Detailed Description
       This depends on Metal.framework	Specifies the spatial normalization gradient filter. The spatial normalization for a feature channel
       applies the filter over local regions which extend spatially, but are in separate feature channels (i.e., they have shape 1 x kernelWidth x
       kernelHeight). 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: Y(i,j) = X(i,j) / (delta + alpha/(kw*kh) * N2(i,j))^beta, where kw and kh are the kernelWidth and the
       kernelHeight. It is the end-users responsibility to ensure that the combination of the parameters delta and alpha does not result in a
       situation where the denominator becomes zero - in such situations the resulting pixel-value is undefined.

       T(i,j) = (delta + alpha/(kw*kh) * N2(i,j)) N = kw * kh

       OutputGradient: dZ/dX(i,j) = T(i,j)^(-beta) * ( dZ/dY(i,j) - (2*alpha*beta*X(i,j)/T(i,j)) * (sum_{l,k in L(i),K(j)} dZ/dY(l,k)*X(l,k)) ) N
       is the kernel size. The window R(k) itself is defined as: L(i) = [i-floor((kw-1)/2), i+floor(kw/2] K(j) = [j-floor((kh-1)/2), j+floor(kh/2]

       For correct gradient computation all parameters must be the same as the original normalization filter.

Method Documentation
   - (nullable instancetype) initWithCoder: (NSCoder *__nonnull) aDecoder(nonnull id< MTLDevice >) device
       NSSecureCoding compatability  While the standard NSSecureCoding/NSCoding method -initWithCoder: should work, since the file can't know
       which device your data is allocated on, we have to guess and may guess incorrectly. To avoid that problem, use initWithCoder:device
       instead.

       Parameters:
	   aDecoder The NSCoder subclass with your serialized MPSKernel
	   device The MTLDevice on which to make the MPSKernel

       Returns:
	   A new MPSKernel object, or nil if failure.

       Reimplemented from MPSCNNGradientKernel.

   - (nonnull instancetype) initWithDevice: (nonnull id< MTLDevice >) device(NSUInteger) kernelWidth(NSUInteger) kernelHeight
       Initialize a spatial normalization filter

       Parameters:
	   device The device the filter will run on
	   kernelWidth The width of the kernel
	   kernelHeight The height of the kernel

       Returns:
	   A valid MPSCNNSpatialNormalization object or nil, if failure.

       NOTE: For now, kernelWidth must be equal to kernelHeight

Property Documentation
   - alpha [read],  [write],  [nonatomic],  [assign]
       The value of alpha. Default is 1.0. Must be non-negative.

   - beta [read],  [write],  [nonatomic],  [assign]
       The value of beta. Default is 5.0

   - delta [read],  [write],  [nonatomic],  [assign]
       The value of delta. Default is 1.0

   - kernelHeight [read],  [nonatomic],  [assign]
       The height of the filter window

   - kernelWidth [read],  [nonatomic],	[assign]
       The width of the filter window

Author
       Generated automatically by Doxygen for MetalPerformanceShaders.framework from the source code.

Version MetalPerformanceShaders-100				  Thu Feb 8 2018			     MPSCNNSpatialNormalizationGradient(3)