IMAQ Read LCD VI

LabView NI Vision

IMAQ Read LCD VI

Owning Palette: Instrument ReadersInstalled With: NI Vision Development Module

Reads an LCD display in an input image using the descriptor of the ROI calculated by the IMAQ Get LCD ROI. IMAQ Read LCD returns the number as a double and as a string. The Segments status output indicates whether the number is recognized properly or any of the digits are not recognized fully. This output returns the status of each of the digits in the display. This VI reads LCD or LED indicators and tolerates light drift.

Examples

IMAQ Read LCD

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LCD/LED (LCD) is a Boolean that controls the indicator type. FALSE corresponds to LCD indicators, and TRUE corresponds to LED indicators. The default is FALSE.

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Image is a reference to the source image.

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ROI Descriptor is a descriptor that defines the region of interest that contains the quadrilaterals surrounding each digit. The ROI is calculated by the IMAQ Get LCD ROI VI.

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Global Rectangle contains the coordinates of the bounding rectangle.

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

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ID refers to whether the contour is the external or internal edge of an ROI.

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Type is the shape type of the contour.

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Coordinates indicates the relative position of the contour.

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Threshold is the threshold that determines whether a segment is ON or OFF. A segment is considered ON if the standard deviation of the pixels along a line profile across the segment is greater than this threshold. Increase this value when using images with high contrast. Lower this value when using images with low contrast. The default is 8.

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Search Sign indicates whether the algorithm must read the sign of the indicator.

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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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Search Decimal Separator determines whether to look for a decimal separator after each digit. The default is FALSE.

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Output string contains the number that has been read from the display. If the decimal separator is ON and the control Search Decimal Separator is TRUE, it is represented in the string by a dot (.) symbol.

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Output value contains the value of the number represented by the display.

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Segments status is an array of clusters containing the state of the segments of each digit. The order of the cluster is illustrated below.

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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.

Examples

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

  • LabVIEW\examples\Vision\3. Applications\LCD Example.vi