MPSImageHistogramEqualization(3)

NAME

       MPSImageHistogramEqualization

SYNOPSIS

       #import <MPSImageHistogram.h>

       Inherits MPSUnaryImageKernel.

   Instance Methods
       (nonnull instancetype) - initWithDevice:histogramInfo:
       (nullable instancetype) - initWithCoder:device:
       (void) -
           encodeTransformToCommandBuffer:sourceTexture:histogram:histogramOffset:

   Properties
       MPSImageHistogramInfo histogramInfo

   Additional Inherited Members

Detailed Description

       The MPSImageHistogramEqualization performs equalizes the histogram of
       an image. The process is divided into three steps.


       1.  Call -initWithDevice:histogramInfo: This creates a
           MPSImageHistogramEqualization object. It is done when the method
           returns.

       2.  Call -encodeTransform:sourceTexture:histogram:histogramOffset: This
           creates a privately held image transform (i.e. a cumulative
           distribution function of the histogram) which will be used to
           equalize the distribution of the histogram of the source image.
           This process runs on a MTLCommandBuffer when it is committed to a
           MTLCommandQueue. It must complete before the next step can be run.
           It may be performed on the same MTLCommandBuffer. The histogram
           argument specifies the histogram buffer which contains the
           histogram values for sourceTexture. The sourceTexture argument is
           used by encodeTransform to determine the number of channels and
           therefore which histogram data in histogram buffer to use. The
           histogram for sourceTexture must have been computed either on the
           CPU or using the MPSImageHistogram kernel

       3.  Call -encodeToCommandBuffer:sourceTexture:destinationTexture: to
           read data from sourceTexture, apply the equalization transform to
           it and write to destination texture. This step is also done on the
           GPU on a MTLCommandQueue.


       You can reuse the same equalization transform on other images to
       perform the same transform on those images. (Since their distribution
       is probably different, they will probably not be equalized by it.) This
       filter usually will not be able to work in place.

Method Documentation

   - (void) encodeTransformToCommandBuffer: (nonnull id< MTLCommandBuffer >)
       commandBuffer(nonnull id< MTLTexture >) source(nonnull id< MTLBuffer >)
       histogram(NSUInteger) histogramOffset
       Encode the transform function to a command buffer using a
       MTLComputeCommandEncoder. The transform function computes the
       equalization lookup table.  The transform function will not begin to
       execute until after the command buffer has been enqueued and committed.
       This step will need to be repeated with the new MPSKernel if
       -copyWithZone:device or -copyWithZone: is called. The transform is
       stored as internal state to the object. You still need to call
       -encodeToCommandBuffer:sourceTexture:destinationTexture: afterward to
       apply the transform to produce a result texture.

       Parameters:
           commandBuffer A valid MTLCommandBuffer.
           source A valid MTLTexture containing the source image for the
           filter.
           histogram A valid MTLBuffer containing the histogram results for an
           image. This filter will use these histogram results to generate the
           cumulative histogram for equalizing the image. The histogram
           results / channel are stored together. The number of channels for
           which histogram results are stored is determined by the number of
           channels in the image. If histogramInfo.histogramForAlpha is false
           and the source image is RGBA then only histogram results for RGB
           channels are stored.
           histogramOffset A byte offset into the histogram MTLBuffer where
           the histogram starts. Must conform to alignment requirements for
           [MTLComputeCommandEncoder setBuffer:offset:atIndex:] offset
           parameter.



   - (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 MPSUnaryImageKernel.

   - (nonnull instancetype) initWithDevice: (nonnull id< MTLDevice >)
       device(const MPSImageHistogramInfo *__nonnull) histogramInfo
       Specifies information about the histogram for the channels of an image.

       Parameters:
           device The device the filter will run on
           histogramInfo Pointer to the MPSHistogramInfo struct

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

Property Documentation

   - histogramInfo [read],  [nonatomic],  [assign]
       Return a structure describing the histogram content  Returns a
       MPSImageHistogramInfo structure describing the format of the histogram.

Author

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





Version MetalPerformanceShaders-Thu2Jul 13 201MPSImageHistogramEqualization(3)


Mac OS X 10.13.1 - Generated Tue Nov  7 07:19:30 CST 2017