MPSImageHistogram(3)

NAME
MPSImageHistogram -

SYNOPSIS

#import <MPSImageHistogram.h>

Inherits MPSKernel.

  Instance Methods
(nonnull instancetype) - initWithDevice:histogramInfo:
(void) - encodeToCommandBuffer:sourceTexture:histogram:histogramOffset:
(size_t) - histogramSizeForSourceFormat:

  Properties
MTLRegion clipRectSource
BOOL zeroHistogram
MPSImageHistogramInfo histogramInfo

  Additional Inherited Members

Detailed Description

The MPSImageHistogram computes the histogram of an image.

Method Documentation

  - (void) encodeToCommandBuffer: (nonnull id< MTLCommandBuffer >) commandBuffer(nonnull id< MTLTexture >) source(nonnull id< MTLBuffer >) histogram(NSUInteger) histogramOffset
Encode the filter to a command buffer using a MTLComputeCommandEncoder. The filter will not begin to execute until after the command buffer has been enqueued and committed.

Parameters:
    commandBuffer A valid MTLCommandBuffer.
    source A valid MTLTexture containing the source image for the filter
    histogram A valid MTLBuffer to receive the histogram results.
    histogramOffset Byte offset into histogram buffer at which to write the histogram results. Must be a multiple of 32 bytes. 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.

  - (size_t) histogramSizeForSourceFormat: (MTLPixelFormat) sourceFormat
The amount of space in the output MTLBuffer the histogram will take up. This convenience function calculates the minimum amount of space needed in the output histogram for the results. The MTLBuffer should be at least this length, longer if histogramOffset is non-zero.

Parameters:
    sourceFormat The MTLPixelFormat of the source image. This is the source parameter of -encodeToCommandBuffer: sourceTexture:histogram:histogramOffset

Returns:
    The number of bytes needed to store the result histograms.

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

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

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

Property Documentation

  - clipRectSource [read], [write], [nonatomic], [assign]
The source rectangle to use when reading data. A MTLRegion that indicates which part of the source to read. If the clipRectSource does not lie completely within the source image, the intersection of the image bounds and clipRectSource will be used. The clipRectSource replaces the MPSUnaryImageKernel offset parameter for this filter. The latter is ignored. Default: MPSRectNoClip, use the entire source texture.

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

  - zeroHistogram [read], [write], [nonatomic], [assign]
Zero-initalize the histogram results Indicates that the memory region in which the histogram results are to be written in the histogram buffer are to be zero-initialized or not. Default: YES.

Author

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