ReadBarcodeRoi
Detect and interpret a 1d barcode within the provided image. For best performance, the code should be horizontally aligned and in the image center.
Syntax
Definition:
HRESULT ReadBarcodeRoi(
HRESULT hrPrev,
ITcVnImage* ipSrcImage,
ITcVnContainer*& ipDecodedData,
ETcVnBarcodeType eBarcodeType,
float& fAngleDeg,
ETcVnBarcodeSearchDirection eSearchDirection = BSD_ANY,
ITcVnContainer** pipContour = nullptr,
LONG nMaxScans = 30
)Parameters
|
Name |
Type |
Default |
Description |
|---|---|---|---|
|
hrPrev |
|
HRESULT indicating the result of previous operations (If SUCCEEDED(hrPrev) equals false, no operation is executed.) | |
|
ipSrcImage |
|
Source image (USINT, 1 channel) | |
|
ipDecodedData |
|
Returns the decoded data (ContainerType_String_SINT) | |
|
eBarcodeType |
|
Type of the barcode (supported: CODE39, CODE128, EAN8, EAN13, ITF, UPCA, UPCE) | |
|
fAngleDeg |
float& |
|
Returns the approximate clockwise rotation angle in degree |
|
eSearchDirection |
BSD_ANY |
Barcode search direction (BSD_ANY first tries horizontal, then vertical) | |
|
pipContour |
nullptr |
Returns 4 approximate code corner points, including the quiet zone. The width is accurate, but the actual height is not measured for performance reasons. Instead, it is statically set to 10% of the width, centered around the scan line that was decoded. (optional, set to 0 if not required; ContainerType_Vector_TcVnPoint2_DINT) | |
|
nMaxScans |
LONG |
30 |
Maximum number of scan lines that are evaluated to find the barcode. The scan always starts at the image center and then alternates up- and downwards with increasing distance, using steps of (ipSrcImage height / nMaxScans). |
Further information
The F_VN_ReadBarcodeRoi function is optimized for the detection of a single barcode within a defined image area (ROI).
Algorithm
To do this, the function uses a customized algorithm that requires the code to be centered in the transferred image. The function first searches for horizontally aligned codes and then for vertically aligned codes in the image.
Parameter
Input image
The ipSrcImage input image must be an 1-channel image with USINT element type (8 bits). The code must be aligned horizontally or vertically in the center of the image.
Read data
The data read from the code are returned as a string in the ipDecodedData container. The container is of the type ContainerType_String_SINT. Once the code has been successfully found and decoded, the content can be exported to a string using the F_VN_ExportContainer_String function.
hr := F_VN_ExportContainer_String(ipDecodedData, sText, nMaxLength, hr);Barcode type
The eBarcodeType parameter defines the barcode type to be read. Only one barcode type can be transferred per function call. The following barcode types from the ETcVnBarcodeType enum are supported:
TCVN_BT_CODE39TCVN_BT_CODE128TCVN_BT_EAN8TCVN_BT_EAN13TCVN_BT_ITFTCVN_BT_UPCATCVN_BT_UPCE
Rotation angle (Return value)
The fAngleDeg return value returns the clockwise rotation angle in 90° steps.
Expert parameters
The expert version F_VN_ReadBarcodeRoiExp contains additional parameters.
Related functions
Required License
TC3 Vision Code Reading