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 (uint32_t backends, int32_t imageWidth, int32_t imageHeight, VPIImageFormat inputFormat, VPIPayload *payload)
	Creates payload for vpiSubmitBackgroundSubtractor. More...
VPIStatus	vpiSubmitBackgroundSubtractor (VPIStream stream, uint32_t backend, VPIPayload payload, VPIImage inFrame, VPIImage outFGMask, VPIImage outBGImage, const VPIBackgroundSubtractorParams *params)
	Submits a background subtractor operation to the stream associated with the given payload. More...

Detailed Description

Separate foreground and background from video.

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Data Structure Documentation

VPIBackgroundSubtractorParams

struct VPIBackgroundSubtractorParams

Structure that defines the parameters for vpiCreateBackgroundSubtractor.

Definition at line 80 of file BackgroundSubtractor.h.

Collaboration diagram for VPIBackgroundSubtractorParams:

Data Fields
uint8_t	detectShadow	The algorithm will detect shadows and mark them if this is set to non-zero value.
float	learningRate	Learning rate that indicates how fast the background model is learnt. This value should be between 0 and 1. 0 means that the background model is not updated at all, 1 means that the background model is completely reinitialized from the last frame.
uint8_t	shadowPixelValue	Pixel value for shadow.
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.

Function Documentation

vpiCreateBackgroundSubtractor()

VPIStatus vpiCreateBackgroundSubtractor	(	uint32_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 backends that are eligible to execute the algorithm. Currently only one backend is accepted.
[in]	imageWidth,imageHeight	Input image dimensions
[in]	inputFormat	Input image format.
[out]	payload	Pointer to memory where the created payload handle will be written to.

Returns

an error code on failure else VPI_SUCCESS

vpiInitBackgroundSubtractorParams()

VPIStatus vpiInitBackgroundSubtractorParams

(

VPIBackgroundSubtractorParams *

params

)

#include <vpi/algo/BackgroundSubtractor.h>

Initializes VPIBackgroundSubtractorParams with default values.

Defaults:

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

Parameters

[in]

params

Structure to be filled with default values.

Returns

an error code on failure else VPI_SUCCESS

vpiSubmitBackgroundSubtractor()

VPIStatus vpiSubmitBackgroundSubtractor	(	VPIStream	stream,
		uint32_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 associated with the given payload.

Runs background subtractor on the incoming image from the video and outputs a foreground mask. Please refer to Limitations and Constraints for information on limitations for some parameters.

Parameters

[in]	stream	The stream where the operation will be queued in.
[in]	backend	Backend that will execute the algorithm. Must be one of the backends specified during payload creation. If 0, VPI will select one of the eligible backends from the payload that accepts the given parameters, usually the fastest one.
[in]	payload	Payload to be submitted along the other parameters.
[in]	inFrame	Incoming frame from the video.
[out]	outFGMask	The output foreground mask as an 8-bit binary image.
[out]	outBGImage	Background image, can pass nullptr if not needed.
[in]	params	algorithm control parameters. Pass NULL to use defaults.

Returns

an error code on failure else VPI_SUCCESS