Background Subtractor

Separate foreground and background from video. More...

Data Structures
struct	VPIBackgroundSubtractorParams
	Structure that defines the parameters for vpiCreateBackgroundSubtractor. More...

Functions
VPIStatus	vpiInitBackgroundSubtractorParams (VPIBackgroundSubtractorParams *params)
	Initializes VPIBackgroundSubtractorParams with default values. More...
VPIStatus	vpiCreateBackgroundSubtractor (uint64_t backends, int32_t imageWidth, int32_t imageHeight, VPIImageFormat inputFormat, VPIPayload *payload)
	Creates payload for vpiSubmitBackgroundSubtractor. More...
VPIStatus	vpiSubmitBackgroundSubtractor (VPIStream stream, uint64_t backend, VPIPayload payload, VPIImage inFrame, VPIImage outFGMask, VPIImage outBGImage, const VPIBackgroundSubtractorParams *params)
	Submits a Background Subtractor operation to the stream. More...

Detailed Description

Separate foreground and background from video.

Refer to Background Subtractor for more details and usage examples.

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Data Structure Documentation

VPIBackgroundSubtractorParams

struct VPIBackgroundSubtractorParams

Structure that defines the parameters for vpiCreateBackgroundSubtractor.

Definition at line 82 of file BackgroundSubtractor.h.

Collaboration diagram for VPIBackgroundSubtractorParams:

Data Fields
float	varThreshold	Threshold on the squared Mahalanobis distance between the pixel and the model to decide whether a pixel is well described by the background model. This parameter does not affect the background update.
uint8_t	detectShadow	The algorithm will detect shadows and mark them if this is set to non-zero value.
uint8_t	shadowPixelValue	Pixel value representing shadow.
float	learningRate	Learning rate that indicates how fast the background model is learnt. This value must be between 0 and 1. Minimum of 0 means that the background model is not updated at all Maximum of 1 means that the background model is completely reinitialized from the last frame.

Function Documentation

vpiInitBackgroundSubtractorParams()

VPIStatus vpiInitBackgroundSubtractorParams

(

VPIBackgroundSubtractorParams *

params

)

#include <vpi/algo/BackgroundSubtractor.h>

Initializes VPIBackgroundSubtractorParams with default values.

Defaults:

• varThreshold: 16
• detectShadow: 1
• shadowPixelValue: 127
• learningRate: 0.001

Parameters

[out]

params

Structure to be filled with default values.

Return values

VPI_ERROR_INVALID_ARGUMENT	params is NULL
VPI_SUCCESS	Operation executed successfully.

vpiCreateBackgroundSubtractor()

VPIStatus vpiCreateBackgroundSubtractor	(	uint64_t	backends,
		int32_t	imageWidth,
		int32_t	imageHeight,
		VPIImageFormat	inputFormat,
		VPIPayload *	payload
	)

#include <vpi/algo/BackgroundSubtractor.h>

Creates payload for vpiSubmitBackgroundSubtractor.

Parameters

[in]	backends	VPI backend that will execute the algorithm. Valid values: VPI_BACKEND_CPU VPI_BACKEND_CUDA Backend must be enabled in current context.
[in]	imageWidth,imageHeight	Input image dimensions. Must be > 0.
[in]	inputFormat	Input image format. The accepted image formats are: VPI_IMAGE_FORMAT_U8 VPI_IMAGE_FORMAT_U16 VPI_IMAGE_FORMAT_NV12 VPI_IMAGE_FORMAT_NV12_ER VPI_IMAGE_FORMAT_RGB8 VPI_IMAGE_FORMAT_RGBA8
[out]	payload	Pointer to the payload variable that receives the created handle.

Return values

VPI_ERROR_INVALID_ARGUMENT	payload is NULL.
VPI_ERROR_INVALID_ARGUMENT	imageWidth or imageHeight outside valid range.
VPI_ERROR_INVALID_ARGUMENT	backend refers to an invalid backend.
VPI_IMAGE_FORMAT_INVALID	inputFormat is not supported.
VPI_ERROR_NOT_IMPLEMENTED	Background Subtractor algorithm is not supported by given backend.
VPI_ERROR_INVALID_CONTEXT	Current context was destroyed.
VPI_ERROR_INVALID_OPERATION	Backend isn't enabled in current context.
VPI_ERROR_OUT_OF_MEMORY	Cannot allocate required resources.
VPI_SUCCESS	Operation executed successfully.

vpiSubmitBackgroundSubtractor()

VPIStatus vpiSubmitBackgroundSubtractor	(	VPIStream	stream,
		uint64_t	backend,
		VPIPayload	payload,
		VPIImage	inFrame,
		VPIImage	outFGMask,
		VPIImage	outBGImage,
		const VPIBackgroundSubtractorParams *	params
	)

#include <vpi/algo/BackgroundSubtractor.h>

Submits a Background Subtractor operation to the stream.

Runs background subtractor on the incoming image from the video and outputs an estimate of the foreground mask.

Parameters

[in]	stream	The stream where the operation will be queued in. Must not be NULL. Stream must have enabled the backends that will execute the algorithm.
[in]	backend	Backend that will execute the algorithm. Must be the backend specified during payload creation or 0 as a shorthand to use this backend.
[in]	payload	Payload to be submitted along the other parameters.
[in]	inFrame	Incoming frame from the video. Must not be NULL. Must have same dimensions as the one specified during payload creation. Image must have enabled the backends that will execute the algorithm.
[out]	outFGMask	The output foreground mask as an 8-bit binary image. Must not be NULL. Must have same dimensions as input image. The only accepted format is VPI_IMAGE_FORMAT_U8. Image must have enabled the backends that will execute the algorithm.
[out]	outBGImage	Background image. Pass NULL if not needed. Must have same format and dimensions as input image. Image must have enabled the backends that will execute the algorithm.
[in]	params	Algorithm control parameters. Pass NULL to use the defaults given by vpiInitBackgroundSubtractorParams.

Return values

VPI_ERROR_INVALID_ARGUMENT	stream is NULL.
VPI_ERROR_INVALID_ARGUMENT	params is NULL.
VPI_ERROR_INVALID_ARGUMENT	inFrame or outFGMask are NULL.
VPI_ERROR_INVALID_ARGUMENT	payload is not created by vpiCreateBackgroundSubtractor.
VPI_ERROR_INVALID_ARGUMENT	inFrame image dimension does not match the one associated with payload.
VPI_ERROR_INVALID_ARGUMENT	outFGMask dimension does not match the one associated with payload.
VPI_ERROR_INVALID_ARGUMENT	Learning rate in params outside valid range.
VPI_ERROR_INVALID_IMAGE_FORMAT	inFrame image format does not match the one associated with payload.
VPI_ERROR_INVALID_IMAGE_FORMAT	outFGMask format not supported.
VPI_ERROR_INVALID_IMAGE_FORMAT	outBGImage format does not match the one associated with payload.
VPI_ERROR_INVALID_ARGUMENT	payload is invalid.
VPI_ERROR_INVALID_OPERATION	The needed backends aren't enabled in stream, inFrame, outFGMask or outBGImage.
VPI_SUCCESS	Operation executed successfully.