User Facing Pyramid API

The Public Pyramid API. More...

Macros
#define	VX_SCALE_PYRAMID_HALF   (0.5f)
	Use to indicate a half-scale pyramid.
#define	VX_SCALE_PYRAMID_ORB   ((vx_float32)0.8408964f)
	Use to indicate a ORB scaled pyramid whose scaling factor is \( \frac{1}{\root 4 \of {2}} \).

Typedefs
typedef struct Pyramid *	vx_pyramid
	The Image Pyramid object. A set of scaled images.

Enumerations
enum	vx_pyramid_attribute_e {   VX_PYRAMID_LEVELS = VX_ATTRIBUTE_BASE(VX_ID_KHRONOS, VX_TYPE_PYRAMID) + 0x0 ,   VX_PYRAMID_SCALE = VX_ATTRIBUTE_BASE(VX_ID_KHRONOS, VX_TYPE_PYRAMID) + 0x1 ,   VX_PYRAMID_WIDTH = VX_ATTRIBUTE_BASE(VX_ID_KHRONOS, VX_TYPE_PYRAMID) + 0x2 ,   VX_PYRAMID_HEIGHT = VX_ATTRIBUTE_BASE(VX_ID_KHRONOS, VX_TYPE_PYRAMID) + 0x3 ,   VX_PYRAMID_FORMAT = VX_ATTRIBUTE_BASE(VX_ID_KHRONOS, VX_TYPE_PYRAMID) + 0x4 }
	The pyramid object attributes. More...

Functions
VX_API_ENTRY vx_pyramid VX_API_CALL	vxCreatePyramid (vx_context context, vx_size levels, vx_float32 scale, vx_uint32 width, vx_uint32 height, vx_df_image format)
	Creates a reference to a pyramid object of the supplied number of levels.
VX_API_ENTRY vx_pyramid VX_API_CALL	vxCreateVirtualPyramid (vx_graph graph, vx_size levels, vx_float32 scale, vx_uint32 width, vx_uint32 height, vx_df_image format)
	Creates a reference to a virtual pyramid object of the supplied number of levels.
VX_API_ENTRY vx_status VX_API_CALL	vxReleasePyramid (vx_pyramid *pyr)
	Releases a reference to a pyramid object. The object may not be garbage collected until its total reference count is zero.
VX_API_ENTRY vx_status VX_API_CALL	vxQueryPyramid (vx_pyramid pyr, vx_enum attribute, void *ptr, vx_size size)
	Queries an attribute from an image pyramid.
VX_API_ENTRY vx_image VX_API_CALL	vxGetPyramidLevel (vx_pyramid pyr, vx_uint32 index)
	Retrieves a level of the pyramid as a vx_image, which can be used elsewhere in OpenVX. A call to vxReleaseImage is necessary to release an image for each call of vxGetPyramidLevel.

Detailed Description

The Public Pyramid API.

Macro Definition Documentation

VX_SCALE_PYRAMID_HALF

#define VX_SCALE_PYRAMID_HALF   (0.5f)

#include <vx_types.h>

Use to indicate a half-scale pyramid.

VX_SCALE_PYRAMID_ORB

#define VX_SCALE_PYRAMID_ORB   ((vx_float32)0.8408964f)

#include <vx_types.h>

Use to indicate a ORB scaled pyramid whose scaling factor is \( \frac{1}{\root 4 \of {2}} \).

Typedef Documentation

vx_pyramid

typedef struct Pyramid* vx_pyramid

#include <vx_types.h>

The Image Pyramid object. A set of scaled images.

Enumeration Type Documentation

vx_pyramid_attribute_e

enum vx_pyramid_attribute_e

#include <vx_types.h>

The pyramid object attributes.

Enumerator
VX_PYRAMID_LEVELS	The number of levels of the pyramid. Read-only. Use a vx_size parameter.
VX_PYRAMID_SCALE	The scale factor between each level of the pyramid. Read-only. Use a vx_float32 parameter.
VX_PYRAMID_WIDTH	The width of the 0th image in pixels. Read-only. Use a vx_uint32 parameter.
VX_PYRAMID_HEIGHT	The height of the 0th image in pixels. Read-only. Use a vx_uint32 parameter.
VX_PYRAMID_FORMAT	The vx_df_image_e format of the image. Read-only. Use a vx_df_image parameter.

Function Documentation

vxCreatePyramid()

VX_API_ENTRY vx_pyramid VX_API_CALL vxCreatePyramid	(	vx_context	context,
		vx_size	levels,
		vx_float32	scale,
		vx_uint32	width,
		vx_uint32	height,
		vx_df_image	format )

#include <vx_api.h>

Creates a reference to a pyramid object of the supplied number of levels.

Parameters

[in]	context	The reference to the overall context.
[in]	levels	The number of levels desired. This is required to be a non-zero value.
[in]	scale	Used to indicate the scale between pyramid levels. This is required to be a non-zero positive value. VX_SCALE_PYRAMID_HALF and VX_SCALE_PYRAMID_ORB must be supported.
[in]	width	The width of the 0th level image in pixels.
[in]	height	The height of the 0th level image in pixels.
[in]	format	The format of all images in the pyramid. NV12, NV21, IYUV, UYVY and YUYV formats are not supported.

Returns

A pyramid reference vx_pyramid containing the sub-images. Any possible errors preventing a successful creation should be checked using vxGetStatus.

Examples

optical_flow.cpp.

vxCreateVirtualPyramid()

VX_API_ENTRY vx_pyramid VX_API_CALL vxCreateVirtualPyramid	(	vx_graph	graph,
		vx_size	levels,
		vx_float32	scale,
		vx_uint32	width,
		vx_uint32	height,
		vx_df_image	format )

#include <vx_api.h>

Creates a reference to a virtual pyramid object of the supplied number of levels.

Virtual Pyramids can be used to connect Nodes together when the contents of the pyramids will not be accessed by the user of the API. All of the following constructions are valid:

vx_context context = vxCreateContext();
vx_graph graph = vxCreateGraph(context);
vx_pyramid virt[] = {
    vxCreateVirtualPyramid(graph, 4, VX_SCALE_PYRAMID_HALF, 0, 0, VX_DF_IMAGE_VIRT), // no dimension and format specified for level 0
    vxCreateVirtualPyramid(graph, 4, VX_SCALE_PYRAMID_HALF, 640, 480, VX_DF_IMAGE_VIRT), // no format specified.
    vxCreateVirtualPyramid(graph, 4, VX_SCALE_PYRAMID_HALF, 640, 480, VX_DF_IMAGE_U8), // no access
};

Parameters

[in]	graph	The reference to the parent graph.
[in]	levels	The number of levels desired. This is required to be a non-zero value.
[in]	scale	Used to indicate the scale between pyramid levels. This is required to be a non-zero positive value. VX_SCALE_PYRAMID_HALF and VX_SCALE_PYRAMID_ORB must be supported.
[in]	width	The width of the 0th level image in pixels. This may be set to zero to indicate to the interface that the value is unspecified.
[in]	height	The height of the 0th level image in pixels. This may be set to zero to indicate to the interface that the value is unspecified.
[in]	format	The format of all images in the pyramid. This may be set to VX_DF_IMAGE_VIRT to indicate that the format is unspecified.

Returns

A pyramid reference vx_pyramid. Any possible errors preventing a successful creation should be checked using vxGetStatus.

Note

Images extracted with vxGetPyramidLevel behave as Virtual Images and cause vxMapImagePatch to return errors.

vxGetPyramidLevel()

VX_API_ENTRY vx_image VX_API_CALL vxGetPyramidLevel	(	vx_pyramid	pyr,
		vx_uint32	index )

#include <vx_api.h>

Retrieves a level of the pyramid as a vx_image, which can be used elsewhere in OpenVX. A call to vxReleaseImage is necessary to release an image for each call of vxGetPyramidLevel.

Parameters

[in]	pyr	The pyramid object.
[in]	index	The index of the level, such that index is less than levels.

Returns

A vx_image reference. Any possible errors preventing a successful function completion should be checked using vxGetStatus.

vxQueryPyramid()

VX_API_ENTRY vx_status VX_API_CALL vxQueryPyramid	(	vx_pyramid	pyr,
		vx_enum	attribute,
		void *	ptr,
		vx_size	size )

#include <vx_api.h>

Queries an attribute from an image pyramid.

Parameters

[in]	pyr	The pyramid to query.
[in]	attribute	The attribute for which to query. Use a vx_pyramid_attribute_e enumeration.
[out]	ptr	The location at which to store the resulting value.
[in]	size	The size in bytes of the container to which ptr points.

Returns

A vx_status_e enumeration.

Return values

VX_SUCCESS	No errors; any other value indicates failure.
VX_ERROR_INVALID_REFERENCE	pyr is not a valid vx_pyramid reference.

vxReleasePyramid()

VX_API_ENTRY vx_status VX_API_CALL vxReleasePyramid

(

vx_pyramid *

pyr

)

#include <vx_api.h>

Releases a reference to a pyramid object. The object may not be garbage collected until its total reference count is zero.

Parameters

[in]

pyr

The pointer to the pyramid to release.

Returns

A vx_status_e enumeration.

Return values

VX_SUCCESS	No errors; any other value indicates failure.
VX_ERROR_INVALID_REFERENCE	pyr is not a valid vx_pyramid reference.

Postcondition

After returning from this function the reference is zeroed.

Examples

optical_flow.cpp.