mojave man page for mpscnncrosschannelnormalizationgradient

MPSCNNCrossChannelNormalizationGradient(3)		 MetalPerformanceShaders.framework		MPSCNNCrossChannelNormalizationGradient(3)

NAME
       MPSCNNCrossChannelNormalizationGradient

SYNOPSIS
       #import <MPSCNNNormalization.h>

       Inherits MPSCNNGradientKernel.

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

   Properties
       float alpha
       float beta
       float delta
       NSUInteger kernelSize

   Additional Inherited Members
Detailed Description
       This depends on Metal.framework	Specifies the normalization gradient filter across feature channels. This normalization filter applies the
       filter to a local region across nearby feature channels, but with no spatial extent (i.e., they have shape kernelSize x 1 x 1). The
       normalized output is given by: Y(i,j,k) = X(i,j,k) / L(i,j,k)^beta, where the normalizing factor is: L(i,j,k) = delta + alpha/N * (sum_{q
       in Q(k)} X(i,j,q)^2, where N is the kernel size. The window Q(k) itself is defined as: Q(k) = [max(0, k-floor(N/2)), min(D-1,
       k+floor((N-1)/2)], where

       k is the feature channel index (running from 0 to D-1) and D is the number of feature channels, and alpha, beta and delta are paremeters.
       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.

       OutputGradient: dZ/dX(i,j,k) = dZ/dY(i,j,k) * (L(i,j,k)^-beta) - 2 * alpha * beta * X(i,j,k) * ( sum_{r in R(k)} dZ/dY(i,j,r) * X(i,j,r) *
       (L(i,j,r) ^ (-beta-1)) ) N is the kernel size. The window L(i) and K(j) itself is defined as: R(k) = [max(0, k-floor((N-1)/2)), min(D-1,
       k+floor(N/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) kernelSize
       Initialize a cross channel normalization gradient filter

       Parameters:
	   device The device the filter will run on
	   kernelSize The kernel filter size in each dimension.

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

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

   - kernelSize [read],  [nonatomic],  [assign]
       The size of the square filter window. Default is 5

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

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