IMAQ Label VI

LabView NI Vision

IMAQ Label VI

Owning Palette: ProcessingInstalled With: NI Vision Development Module

Labels the particles in a binary image.

Details Examples

IMAQ Label

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Image Src is a reference to the source image.

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Image Dst is a reference to the destination image.

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Connectivity 4/8 (8) specifies the type of connectivity used by the algorithm for particle detection. The connectivity mode directly determines whether an adjacent pixel belongs to the same particle or a different particle. The default is 8. The following values are possible:

8 (TRUE) Particle detection is performed in connectivity mode 8
4 (FALSE) Particle detection is performed in connectivity mode 4
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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.

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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.

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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.

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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.

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Image Dst Out is a reference to the destination image. If Image Dst is connected, Image Dst Out is the same as Image Dst. Otherwise, Image Dst Out refers to the image referenced by Image Src.

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Number of Particles indicates the number of particles detected in the image.

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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.

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status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.

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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.

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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.

Details

This operation applies a unique grayscale value to all pixels composing the same group of pixels (a particle). This value is encoded in 8 or 16 bits, depending on the image type. Therefore, 255 particles can be labeled in an 8-bit image and 65,535 particles in a 16-bit image.

If you want to label more than 255 particles in an 8-bit image, you can cast the image into a 16-bit image using the IMAQ Cast Image VI and then label the particles.

Examples

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

  • LabVIEW\examples\Vision\2. Functions\Grayscale Processing\Label Example.vi

  • LabVIEW\examples\Vision\2. Functions\Calibration\Nonlinear Calibration Example.llb