imaqReadQRCode

NI Vision for LabWindows/CVI Function

imaqReadQRCode

Usage

QRCodeReport* imaqReadQRCode(Image* image, const ROI* roi, QRGradingMode reserved, const QRCodeDescriptionOptions* descriptionOptions, const QRCodeSizeOptions* sizeOptions, const QRCodeSearchOptions* searchOptions);

Purpose

Locates and reads the value encoded in a QR code. You can compare the decoded data to a reference string or check whether the data contains a specific pattern. Many of the options provided by this function allow for automatic detection of properties of the QR code or what methods the function should use to locate and decode the code. Selecting specific properties and methods for these options will greatly increase the performance of the function.

Image Types Supported

IMAQ_IMAGE_U8

Parameters

Name

Type

Description

image Image* The image containing the QR code to be detected.
roi const ROI* A region of interest specifying the location of the code in the image. The first contour of roi must be a rectangle, rotated rectangle, or closed contour. If skipLocation of the searchOptions parameter is set to TRUE, a closed contour has an additional constraint of being four-sided. Set this parameter to NULL to use the entire image.
reserved QRGradingMode This is reserved for future use. Set this parameter to IMAQ_QR_NO_GRADING.
descriptionOptions const QRCodeDescriptionOptions* Describes the QR code the function should look for.
sizeOptions const QRCodeSizeOptions* Describes sizing information for the QR code the function should look for.
searchOptions const QRCodeSearchOptions* Describes the methods and limitations the function should use when searching for the QR code.

Return Value

Type

Description

QRCodeReport* On success, this function returns a structure containing information about the QR code. On failure, this function returns NULL. To get extended error information, call imaqGetLastError(). When you are finished with this structure, dispose of it by calling imaqDispose().

Parameter Discussion

descriptionOptions—Set descriptionOptions to NULL to use the following default values:

dimensions IMAQ_QR__DIMENSIONS_AUTO_DETECT
polarity IMAQ_QR_POLARITY_AUTO_DETECT
mirror IMAQ_QR_MIRROR_MODE_AUTO_DETECT
modelType IMAQ_QR_MODELTYPE_AUTO_DETECT

sizeOptions—Set sizeOptions to NULL to use the following default values:

minSize 0
maxSize 0

searchOptions—Set searchOptions to NULL to use the following default values:

rotationMode IMAQ_QR_ROTATION_MODE_UNLIMITED
skipLocation FALSE
edgeThreshold 30
demodulationMode IMAQ_QR_DEMODULATION_MODE_AUTO_DETECT
cellSampleSize IMAQ_QR_CELL_SAMPLE_SIZE_AUTO_DETECT
cellFilterMode IMAQ_QR_CELL_FILTER_MODE_AUTO_DETECT
skewDegreesAllowed 5