MPSImageHistogramSpecification(3)
NAME
MPSImageHistogramSpecification
SYNOPSIS
#import <MPSImageHistogram.h>
Inherits MPSUnaryImageKernel.
Instance Methods
(nonnull instancetype) - initWithDevice:histogramInfo:
(nullable instancetype) - initWithCoder:device:
(void) -
encodeTransformToCommandBuffer:sourceTexture:sourceHistogram:sourceHistogramOffset:desiredHistogram:desiredHistogramOffset:
Properties
MPSImageHistogramInfo histogramInfo
Additional Inherited Members
Detailed Description
The MPSImageHistogramSpecification performs a histogram specification
operation on an image. It is a generalized version of histogram
equalization operation. The histogram specificaiton filter converts the
image so that its histogram matches the desired histogram.
Method Documentation
- (void) encodeTransformToCommandBuffer: (nonnull id< MTLCommandBuffer >)
commandBuffer(nonnull id< MTLTexture >) source(nonnull id< MTLBuffer >)
sourceHistogram(NSUInteger) sourceHistogramOffset(nonnull id< MTLBuffer
>) desiredHistogram(NSUInteger) desiredHistogramOffset
Encode the transform function to a command buffer using a
MTLComputeCommandEncoder. The transform function computes the
specification 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.
Parameters:
commandBuffer A valid MTLCommandBuffer.
source A valid MTLTexture containing the source image for the
filter.
sourceHistogram A valid MTLBuffer containing the histogram results
for the source 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.
sourceHistogramOffset A byte offset into the sourceHistogram
MTLBuffer where the histogram starts. Must conform to alignment
requirements for [MTLComputeCommandEncoder
setBuffer:offset:atIndex:] offset parameter.
desiredHistogram A valid MTLBuffer containing the desired histogram
results for the source 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.
desiredHistogramOffset A byte offset into the desiredHistogram
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.
The MPSImageHistogramSpecification applies a transfor to convert the
histogram to a specified histogram. The process is divided into three
steps:
1. Call -initWithDevice:histogramInfo: This creates a
MPSImageHistogramSpecification object. It is done when the method
returns.
2. Call
-encodeTransform:sourceTexture:sourceHistogram:sourceHistogramOffset:desiredHistogram:
desiredHistogramOffset: This creates a privately held image
transform which will convert the the distribution of the source
histogram to the desired histogram. 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 sourceTexture argument is used by
encodeTransform to determine the number of channels and therefore
which histogram data in sourceHistogram buffer to use. The
sourceHistogram and desiredHistogram 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 transform to it and write
to destination texture. This step is also done on the GPU on a
MTLCommandQueue.
You can reuse the same specification transform on other images to
perform the same transform on those images. (Since their starting
distribution is probably different, they will probably not arrive at
the same distribution as the desired histogram.) This filter usually
will not be able to work in place.
Parameters:
device The device the filter will run on
histogramInfo Pointer to the MPSHistogramInfo struct
Returns:
A valid MPSImageHistogramSpecification 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 20MPSImageHistogramSpecification(3)
Mac OS X 10.13.1 - Generated Tue Nov 7 07:20:19 CST 2017
