Gray8 image pyramid: a base image and its successively halved levels. More...

#include <SimdPyramid.hpp>

Public Types
typedef A< uint8_t >	Allocator

Public Member Functions
	Pyramid ()

	Pyramid (const Point< ptrdiff_t > &size, size_t levelCount)

	Pyramid (size_t width, size_t height, size_t levelCount)

void	Recreate (Point< ptrdiff_t > size, size_t levelCount)

void	Recreate (size_t width, size_t height, size_t levelCount)

size_t	Size () const

View< A > &	operator[] (size_t level)

const View< A > &	operator[] (size_t level) const

View< A > &	At (size_t level)

const View< A > &	At (size_t level) const

View< A > &	Top ()

const View< A > &	Top () const

void	Swap (Pyramid< A > &pyramid)

Detailed Description

template<template< class > class A>
struct Simd::Pyramid< A >

Gray8 image pyramid: a base image and its successively halved levels.

Pyramid stores 8-bit gray views. Level 0 is the base, the largest image. Each following level is half of the previous one on both sides. The half-size is Simd::Scale: each side n becomes (n + 1) / 2, so an odd side rounds up. A 16x16 pyramid of 3 levels is 16x16, 8x8 and 4x4 (TestCheckCpp). A 15x9 pyramid of 3 levels is 15x9, 8x5 and 4x3. Those sizes are the sizes written by Simd::ReduceGray, so Simd::Build fills the views allocated here.

The template argument A is the allocator template of the levels. In-tree code uses Simd::Allocator. Every level is a View of format Gray8. Recreate allocates the buffers and leaves the pixels uninitialized. Callers write level 0 and then fill the upper levels with Simd::Build, or they write every level with Simd::Fill. Simd::Copy copies a whole pyramid onto another pyramid of the same level count. Fill, Copy and Build are declared in SimdLib.hpp.

Size() is the number of levels. The base image size is operator[](0).Size(). At(level) and operator[](level) return the same view. The index must be less than Size(). Top() is the last level, the smallest image.

Motion::Detector keeps several of these pyramids. Calibration walks the frame size with Simd::Scale until the top level is smaller than the top-level size minimum or the estimated object area is below its minimum. The number of skipped fine levels is then clamped by Options::CalibrationScaleLevelMax (the default 3 is an 8-times downscale). The scaled pyramid is recreated at the original frame size. SetFrame converts the input frame into scaled[0] and calls Simd::Build(scaled, SimdReduce2x2). The texture pyramid then copies scaled.Top() into its own level 0 and is reduced with SimdReduce4x4. The ROI mask, difference image and segmentation mask are pyramids of the working frame size. The ROI mask is either resized from Model::mask into level 0 or filled with Simd::Fill and a polygon on level 0, then built with SimdReduce4x4. Options::DebugDrawLevel selects the pyramid level copied into the debug inset (difference, gray, dx or dy, chosen by Options::DebugDrawBottomRight).

ShiftDetector::ShiftDetector recreates a background pyramid and a current pyramid at the background size. SetBackground writes level 0 and calls Simd::Build with SimdReduce2x2. Estimate writes the current image into a region of current[0] and reduces that region into the upper levels. The search starts at the coarsest level and doubles the shift on the way to the next finer level.

Font::Resize builds a temporary pyramid when a glyph has to be reduced. Level 0 is a bilinear resize of the original glyph. Simd::Build with SimdReduce2x2 writes the reduced glyph at the last level, and that view is copied into the glyph cache.

TestCheckCpp creates two pyramids of 16x16 and 3 levels, fills the first with the byte 1, builds it with SimdReduce2x2 and copies it onto the second.

Recreate on an existing pyramid returns immediately when level 0 already has the requested size. The level count is not part of that comparison, so a second Recreate with the same base size keeps the old levels and their pixels. A default-constructed pyramid is empty: Size() is 0, and operator[], At and Top require at least one level.

Using example:

#include "Simd/SimdLib.hpp"
 
int main()
{
    typedef Simd::View<Simd::Allocator> View;
    typedef Simd::Pyramid<Simd::Allocator> Pyramid;
    typedef Simd::Point<ptrdiff_t> Point;
 
    View image(320, 240, View::Gray8);
    Pyramid pyramid(image.Size(), 4);
    Simd::Copy(image, pyramid[0]);
    Simd::Build(pyramid, SimdReduce2x2);
 
    View coarse = pyramid.Top();
    Point half = Simd::Scale(image.Size());
 
    Pyramid copy(image.Size(), pyramid.Size());
    Simd::Copy(pyramid, copy);
    return (int)pyramid.Size() + (int)coarse.width + (int)half.x;
}

Related Functions.

Member Typedef Documentation

◆ Allocator

typedef A<uint8_t> Allocator

Allocator of the Gray8 levels. In-tree code passes Simd::Allocator.

Constructor & Destructor Documentation

◆ Pyramid() [1/3]

SIMD_INLINE Pyramid

Creates an empty pyramid.

Size() is 0. Recreate, or a constructor with a base size and a level count, allocates the levels. operator[], At and Top require a pyramid that already has levels.

◆ Pyramid() [2/3]

SIMD_INLINE Pyramid	(	const Point< ptrdiff_t > &	size,
		size_t	levelCount
	)

Creates a pyramid and allocates its levels.

Equivalent to an empty pyramid followed by Recreate(size, levelCount). Level 0 has the given size and format Gray8. Each next level has size Simd::Scale of the previous level. The pixel buffers are allocated and left uninitialized. Motion texture features allocate through Recreate. Font::Resize and TestCheckCpp use the width/height constructor.

Parameters

[in]	size	- width and height of level 0.
[in]	levelCount	- number of levels, including level 0.

◆ Pyramid() [3/3]

SIMD_INLINE Pyramid	(	size_t	width,
		size_t	height,
		size_t	levelCount
	)

Creates a pyramid and allocates its levels.

Forwards to Recreate(Point<ptrdiff_t>(width, height), levelCount). TestCheckCpp uses Pyramid(16, 16, 3): level 0 is 16x16, level 1 is 8x8 and level 2 is 4x4. Font::Resize uses Pyramid(size, level + 1), where size is the current glyph size shifted left by level, so the last level is the reduced glyph.

Parameters

[in]	width	- width of level 0.
[in]	height	- height of level 0.
[in]	levelCount	- number of levels, including level 0.

Member Function Documentation

◆ Recreate() [1/2]

SIMD_INLINE void Recreate	(	Point< ptrdiff_t >	size,
		size_t	levelCount
	)

Allocates or replaces the pyramid levels.

When the pyramid already has levels and size equals the size of level 0, the function returns and leaves the levels and their pixels unchanged. The level count is not compared. Motion::Detector::Calibrate returns before Recreate when the input frame size is unchanged, and recreates the pyramids after the frame size changes. The first Recreate on an empty pyramid always allocates.

Otherwise the pyramid is resized to levelCount views. Level 0 is recreated as Gray8 of the given size. Each next level is Gray8 of Simd::Scale of the previous size. The new buffers are uninitialized. ShiftDetector::ShiftDetector calls the width/height overload for the background and current pyramids. Motion::Detector recreates the scaled pyramid at the original frame size with scaleLevel + 1 levels, and recreates the texture, difference, buffer, segmentation mask and ROI mask pyramids at the working frame size.

Parameters

[in]	size	- width and height of level 0.
[in]	levelCount	- number of levels, including level 0.

◆ Recreate() [2/2]

SIMD_INLINE void Recreate	(	size_t	width,
		size_t	height,
		size_t	levelCount
	)

Allocates or replaces the pyramid levels.

Forwards to Recreate(Point<ptrdiff_t>(width, height), levelCount). The same early return applies: an existing pyramid whose level 0 already has this width and height is left unchanged.

Parameters

[in]	width	- width of level 0.
[in]	height	- height of level 0.
[in]	levelCount	- number of levels, including level 0.

◆ Size()

SIMD_INLINE size_t Size

Returns the number of levels.

This is the level count. The image size of the base is operator[](0).Size(). An empty pyramid returns 0. Simd::Fill, Simd::Copy and Simd::Build loop while the index is less than Size(). Simd::Copy requires both pyramids to have the same Size(). ShiftDetector counts levels of the current pyramid while the search rectangle still has enough area.

Returns: the number of levels.

◆ operator[]() [1/2]

SIMD_INLINE View< A > & operator[] ( size_t level )

Returns the Gray8 view at the given level.

Level 0 is the base. The index must be less than Size(). At(level) returns the same view. Motion, ShiftDetector and Font index pyramids with this operator: scaled[0] receives the converted frame, roiMask[0] receives the ROI image, and the font copies pyramid[level] after Simd::Build. Simd::Fill(difference[i], 0) fills that one view.

Parameters

[in] level - a level index, from 0 up to Size() - 1.

Returns: a reference to the Gray8 image at that level.

◆ operator[]() [2/2]

SIMD_INLINE const View< A > & operator[] ( size_t level ) const

Returns the Gray8 view at the given level.

Equivalent to the non-constant operator[]. Difference estimation reads texture levels through a constant pyramid. The index must be less than Size().

Parameters

[in] level - a level index, from 0 up to Size() - 1.

Returns: a constant reference to the Gray8 image at that level.

◆ At() [1/2]

SIMD_INLINE View< A > & At ( size_t level )

Returns the Gray8 view at the given level.

Equivalent to operator[](level). Simd::Fill, Simd::Copy and Simd::Build in SimdLib.hpp call At to walk the levels.

Parameters

[in] level - a level index, from 0 up to Size() - 1.

Returns: a reference to the Gray8 image at that level.

◆ At() [2/2]

SIMD_INLINE const View< A > & At ( size_t level ) const

Returns the Gray8 view at the given level.

Equivalent to the constant operator[](level).

Parameters

[in] level - a level index, from 0 up to Size() - 1.

Returns: a constant reference to the Gray8 image at that level.

◆ Top() [1/2]

SIMD_INLINE View< A > & Top

Returns the last level, the smallest image.

The pyramid must contain at least one level. For levels 0 .. Size() - 1 this is operator[](Size() - 1). Motion copies scaled.Top() into level 0 of the texture pyramid: that view is the working resolution after the calibration downscale. Font::Resize reads the reduced glyph from the last level, the same view Top() returns.

Returns: a reference to the smallest Gray8 level.

◆ Top() [2/2]

SIMD_INLINE const View< A > & Top

Returns the last level, the smallest image.

Equivalent to the non-constant Top(). The pyramid must contain at least one level.

Returns: a constant reference to the smallest Gray8 level.

◆ Swap()

SIMD_INLINE void Swap ( Pyramid< A > & pyramid )

Exchanges the levels of two pyramids.

Both level vectors are swapped. Each pyramid then has the other pyramid's level count, image sizes and pixel buffers. An empty pyramid can be exchanged with a pyramid that already has levels.

Parameters

[in,out] pyramid - a pyramid whose levels are exchanged with this one.

Simd Library Documentation.

Public Types

Public Member Functions

Detailed Description

Member Typedef Documentation

◆ Allocator

Constructor & Destructor Documentation

◆ Pyramid() [1/3]

◆ Pyramid() [2/3]

◆ Pyramid() [3/3]

Member Function Documentation

◆ Recreate() [1/2]

◆ Recreate() [2/2]

◆ Size()

◆ operator[]() [1/2]

◆ operator[]() [2/2]

◆ At() [1/2]

◆ At() [2/2]

◆ Top() [1/2]

◆ Top() [2/2]

◆ Swap()