IMAQ Extract HOG Feature Vector VI

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Updated2023-02-21
5 minute(s) read

Owning Palette: Analysis
Requires: NI Vision Development Module

Extracts features from an image using the histogram of oriented gradients (HOG) algorithm.

Examples

Supported Image Types

8-bit unsigned grayscale 16-bit unsigned grayscale 16-bit signed grayscale

IMAQ Extract HOG Feature Vector

Image is a reference to the source image.

ROI Descriptor is a descriptor that defines the region within which to search for corners.

Global Rectangle contains the coordinates of the bounding rectangle.

Contours are each of the individual shapes that define an ROI.

	ID refers to whether the contour is the external or internal edge of an ROI.
	Type is the shape type of the contour.
	Coordinates indicates the relative position of the contour.

Feature Extraction Options specifies how the features are extracted from the image.

Grid Size is a cluster that specifies the size, in number, of the blocks along X and Y directions that the VI uses when extracting the features. The default size is 1 x 1 block. For example, if the Grid Size is X = 3 and Y = 5, the image or the ROI is divided into 3 x 5 blocks, 3 in the X direction and 5 in the Y direction.

	X is the grid size in the X-dimension.
	Y is the grid size in the Y-dimension.

Histogram Bins specifies the number of bins per band to use for the object description. The default is 9.

error in (no error) describes the error status before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.

	status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
	code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
	source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

Image (duplicate) is the reference to the image from which features were extracted.

Feature Vector contains the extracted features in the image

error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.

	status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
	code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
	source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

Examples

Refer to the following for an example that uses this VI.

LabVIEW\examples\Vision\HOG-LBP Texture Classification.vi

NI Vision for LabVIEW

Table of Contents

IMAQ Extract HOG Feature Vector VI

Supported Image Types

Examples