IMAQ FPGA SimpleEdge VI

Sub-Pixel Accuracy determines the accuracy required for the location of the edge coordinates. Setting this control to FALSE enables fast edge detection. A subpixel localization of the edges is obtained when this control is TRUE. The subpixel result is computed using a local quadratic interpolation. The default is FALSE.

Process determines the type of search. Choose from the following values:

Pixel Bus In when Input Valid is TRUE, contains one of the following: valid pixel data, an end of line signal, or an end of image signal.

	Pixel Data is the value of the pixel.
	DV Data valid. Determines whether the Pixel Data element should be use (TRUE) or ignored (FALSE).
	EOL End of line. When TRUE, indicates that the end of the line has been reached.
	EOI End of image. When TRUE, indicates that the end of the image has been reached.
	Data Type is used in the block diagram for determining the type of the Pixel Bus. Unused during processing and gets optimized out of the compiled bit stream.

Line specifies the pixel coordinates of the input line. The maximum length allowed is 2600 pixels. The VI accepts new line coordinates at the first valid pixel (start) of each image. The coordinates of all the points along the line are recomputed for each new image.

Note  The point of the line that is closet to the bottom of the image must be separated from the last pixel in the image by at least the length of the line.

	Start X specifies the x-coordinate of the beginning point of the line.
	Start Y specifies the y-coordinate of the beginning point of the line.
	End X specifies the x-coordinate of the end point of the line.
	End Y specifies the y-coordinate of the end point of the line.

Threshold Parameters is a cluster containing information used to determine whether a change in pixel value is considered as an edge.

	Level Type chooses between looking for peaks (positive-going bumps) and valleys (negative-going bumps).
	Threshold Level can be either absolute or relative. Absolute threshold is based on the pixel values. Relative threshold is expressed as a percentage of the pixel-value range found along the path defined by the pixel coordinates.
	Hysteresis can be either absolute or relative. This parameter determines the difference in threshold level between a rising and a falling edge, enabling accurate detection in noisy images.

Input Valid specifies whether the next data point has arrived for processing. Wire the Output Valid output of an upstream node to this input to transfer data from the upstream node to this node.

Ready For Output specifies whether downstream nodes are ready for this node to return a new value. The default is TRUE. Use a Feedback Node to wire the Ready for Input output of a downstream node to this input of the current node.

Note  If this terminal is FALSE during a given cycle, the output valid terminal returns FALSE during that cycle.

Edge Coordinates contains information about the edge that is found. This cluster returns the x- and y-coordinate of the edge and the position (ID) of the edge along the line. The edges found along the line are output after all the edges along the line have been detected. The detected edges are output in consecutive cycles and during this period Output Valid is TRUE.

	X is the X-coordinate of the edge.
	Y is the Y-coordinate of the edge.
	ID is an identifier for the edge found.

Number of Edges specifies the number of edges found. This output remains constant while Output Valid is TRUE. The maximum number of edges that can be found is 256.

Output Valid returns TRUE if this node has computed a result that downstream nodes can use. Wire this output to the Input Valid input of a downstream node to transfer data from the node to the downstream node.

Ready for Input returns TRUE if this node is ready to accept new input data. Use a Feedback Node to wire this output to the Ready for Output input of an upstream node.

Note  If this terminal returns FALSE during a given cycle, LabVIEW discards any data that other nodes send to this node during the following cycle. LabVIEW discards this data even if the Input Valid terminal is TRUE during the following cycle.

Subpixel? determines the accuracy required for the location of the edge coordinates. Setting this control to FALSE enables fast edge detection. A subpixel localization of the edges is obtained when this control is TRUE. The subpixel result is computed using a local quadratic interpolation. The default is FALSE.

Process determines the type of search. Choose from the following values:

Pixel Bus In when Input Valid is TRUE, contains one of the following: valid pixel data, an end of line signal, or an end of image signal.

	Pixel Data is the value of the pixel.
	DV Data valid. Determines whether the Pixel Data element should be use (TRUE) or ignored (FALSE).
	EOL End of line. When TRUE, indicates that the end of the line has been reached.
	EOI End of image. When TRUE, indicates that the end of the image has been reached.
	Data Type is used in the block diagram for determining the type of the Pixel Bus. Unused during processing and gets optimized out of the compiled bit stream.

Line specifies the pixel coordinates of the input line. The maximum length allowed is 2600 pixels. The VI accepts new line coordinates at the first valid pixel (start) of each image. The coordinates of all the points along the line are recomputed for each new image.

Note  The point of the line that is closet to the bottom of the image must be separated from the last pixel in the image by at least the length of the line.

	Start X specifies the x-coordinate of the beginning point of the line.
	Start Y specifies the y-coordinate of the beginning point of the line.
	End X specifies the x-coordinate of the end point of the line.
	End Y specifies the y-coordinate of the end point of the line.

Threshold Parameters is a cluster containing information used to determine whether a change in pixel value is considered as an edge.

	Level Type chooses between looking for peaks (positive-going bumps) and valleys (negative-going bumps).
	Threshold Level can be either absolute or relative. Absolute threshold is based on the pixel values. Relative threshold is expressed as a percentage of the pixel-value range found along the path defined by the pixel coordinates.
	Hysteresis can be either absolute or relative. This parameter determines the difference in threshold level between a rising and a falling edge, enabling accurate detection in noisy images.

Input Valid specifies whether the next data point has arrived for processing. Wire the Output Valid output of an upstream node to this input to transfer data from the upstream node to this node.

Ready For Output specifies whether downstream nodes are ready for this node to return a new value. The default is TRUE. Use a Feedback Node to wire the Ready for Input output of a downstream node to this input of the current node.

Note  If this terminal is FALSE during a given cycle, the output valid terminal returns FALSE during that cycle.

Edge Coordinates contains information about the edge that is found. This cluster returns the x- and y-coordinate of the edge and the position (ID) of the edge along the line. The edges found along the line are output after all the edges along the line have been detected. The detected edges are output in consecutive cycles and during this period Output Valid is TRUE.

	X is the X-coordinate of the edge.
	Y is the Y-coordinate of the edge.
	ID is an identifier for the edge found.

Number of Edges specifies the number of edges found. This output remains constant while Output Valid is TRUE. The maximum number of edges that can be found is 256.

Output Valid returns TRUE if this node has computed a result that downstream nodes can use. Wire this output to the Input Valid input of a downstream node to transfer data from the node to the downstream node.

Ready for Input returns TRUE if this node is ready to accept new input data. Use a Feedback Node to wire this output to the Ready for Output input of an upstream node.

Note  If this terminal returns FALSE during a given cycle, LabVIEW discards any data that other nodes send to this node during the following cycle. LabVIEW discards this data even if the Input Valid terminal is TRUE during the following cycle.