IMAQ Extract VI

LabView NI Vision

IMAQ Extract VI

Owning Palette: Image ManipulationInstalled With: NI Vision Development Module

Extracts (reduces) an image or part of an image with adjustment of the horizontal and vertical resolution.

Details Examples

IMAQ Extract

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Optional Rectangle defines a four-element array that contains the left, top, right, and bottom coordinates of the region to process. The VI applies the operation to the entire image if Optional Rectangle is empty or not connected.

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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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X Step Size is the vertical sampling step, which defines the columns to be extracted (the horizontal reduction ratio). For example, with an X Step Size equal to 3, one out of every three columns is extracted from the Image Src into the Image Dst. Each column is extracted if the default value (1) is used.

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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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Y Step Size is the horizontal sampling step, which defines the lines to be extracted (the vertical reduction ratio). Each row is extracted if the default value (1) is used.

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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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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

For example, if a 512 × 512 image is connected and the X Step Size and Y Step Size are both equal to 2, the resulting image has a resolution of 256 × 256. The resulting image contains the lines from the Image Src 0, 2, 4, ..., 510 and the columns 0, 2, 4, ..., 510 from the Image Src.

Image Src and Image Dst must be of the same image type.

The following figure illustrates an extraction of an image where X Step Size equals 2 and Y Step Size equals 3. Example of Image Extraction

Examples

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

  • LabVIEW\examples\Vision\2. Functions\Image Management\Extract Example.vi

  • LabVIEW\examples\Vision\3. Applications\Mechanical Assembly Example.vi