eVision.ECannyEdgeDetector Class Reference

Manages a complete context for the Canny edge detector. More...

Public Member Functions
None	__init__ (self)
	Constructs a eVision.ECannyEdgeDetector object initialized to its default values.
None	ResetSmoothingScale (self)
	Prevents the smoothing of the source image by a Gaussian filter.
None	Apply (self, eVision.EROIBW8 source, eVision.EROIBW8 result)
	Apply the Canny edge detector on an image/ROI.
None	Apply (self, eVision.EROIBW8 source, eVision.ERegion region, eVision.EROIBW8 result)
	Apply the Canny edge detector on an image/ROI.
None	Apply (self, eVision.EROIBW8 source, eVision.ERegion region, eVision.EFrame frame, eVision.EROIBW8 result)
	Apply the Canny edge detector on an image/ROI.
float	SmoothingScale (self)
	The scale of the features of interest.
	SmoothingScale (self, float value)
	The scale of the features of interest.
eVision.ECannyThresholdingMode	ThresholdingMode (self)
	Returns the mode of the hysteresis thresholding.
	ThresholdingMode (self, eVision.ECannyThresholdingMode value)
	Returns the mode of the hysteresis thresholding.
float	LowThreshold (self)
	Returns the low hysteresis threshold for a pixel to be considered as an edge.
	LowThreshold (self, float value)
	Returns the low hysteresis threshold for a pixel to be considered as an edge.
float	HighThreshold (self)
	Returns the high hysteresis threshold for a pixel to be considered as an edge.
	HighThreshold (self, float value)
	Returns the high hysteresis threshold for a pixel to be considered as an edge.

Detailed Description

Manages a complete context for the Canny edge detector.

Remarks:

The Canny edge detector operates on a grayscale BW8 image and delivers a black-and-white BW8 image where pixels have only 2 possible values: 0 and 255. Pixels corresponding to edges in the source image are set to value 255 in the output image; The other pixels are set to value 0.

License(s): EasyImage

Constructor & Destructor Documentation

__init__()

None eVision.ECannyEdgeDetector.__init__

(

self

)

Constructs a eVision.ECannyEdgeDetector object initialized to its default values.

Member Function Documentation

Apply() [1/3]

None eVision.ECannyEdgeDetector.Apply	(		self,
		eVision.EROIBW8	source,
		eVision.ERegion	region,
		eVision.EFrame	frame,
		eVision.EROIBW8	result )

Apply the Canny edge detector on an image/ROI.

Remarks:

The output ROI must have the same size than the input ROI.

Parameters

source	The source image/ROI.
region	The region on which to apply the method.
frame	The reference frame of the region.
result	The output image/ROI.

Apply() [2/3]

None eVision.ECannyEdgeDetector.Apply	(		self,
		eVision.EROIBW8	source,
		eVision.ERegion	region,
		eVision.EROIBW8	result )

Apply the Canny edge detector on an image/ROI.

Remarks:

The output ROI must have the same size than the input ROI.

Parameters

source	The source image/ROI.
region	The region on which to apply the method.
result	The output image/ROI.

Apply() [3/3]

None eVision.ECannyEdgeDetector.Apply	(		self,
		eVision.EROIBW8	source,
		eVision.EROIBW8	result )

Apply the Canny edge detector on an image/ROI.

Remarks:

The output ROI must have the same size than the input ROI.

Parameters

source	The source image/ROI.
result	The output image/ROI.

HighThreshold() [1/2]

float eVision.ECannyEdgeDetector.HighThreshold

(

self

)

Returns the high hysteresis threshold for a pixel to be considered as an edge.

HighThreshold() [2/2]

eVision.ECannyEdgeDetector.HighThreshold	(		self,
		float	value )

Returns the high hysteresis threshold for a pixel to be considered as an edge.

LowThreshold() [1/2]

float eVision.ECannyEdgeDetector.LowThreshold

(

self

)

Returns the low hysteresis threshold for a pixel to be considered as an edge.

LowThreshold() [2/2]

eVision.ECannyEdgeDetector.LowThreshold	(		self,
		float	value )

Returns the low hysteresis threshold for a pixel to be considered as an edge.

ResetSmoothingScale()

None eVision.ECannyEdgeDetector.ResetSmoothingScale

(

self

)

Prevents the smoothing of the source image by a Gaussian filter.

Remarks:

Calling this method is equivalent to set eVision.ECannyEdgeDetector.SmoothingScale to zero. It disables the use of the Gaussian filter.

SmoothingScale() [1/2]

float eVision.ECannyEdgeDetector.SmoothingScale

(

self

)

The scale of the features of interest.

Remarks:

This scale corresponds to the standard deviation of the Gaussian filter that is used to smooth the source image before the computation of the gradient, hereby selecting the scale of the features of interest.

If this scale is set to zero, no smoothing is achieved: The gradient is computed directly on the raw source image, speeding up the detector, but making the process much less reliable.

SmoothingScale() [2/2]

eVision.ECannyEdgeDetector.SmoothingScale	(		self,
		float	value )

The scale of the features of interest.

Remarks:

This scale corresponds to the standard deviation of the Gaussian filter that is used to smooth the source image before the computation of the gradient, hereby selecting the scale of the features of interest.

If this scale is set to zero, no smoothing is achieved: The gradient is computed directly on the raw source image, speeding up the detector, but making the process much less reliable.

ThresholdingMode() [1/2]

eVision.ECannyThresholdingMode eVision.ECannyEdgeDetector.ThresholdingMode

(

self

)

Returns the mode of the hysteresis thresholding.

ThresholdingMode() [2/2]

eVision.ECannyEdgeDetector.ThresholdingMode	(		self,
		eVision.ECannyThresholdingMode	value )

Returns the mode of the hysteresis thresholding.