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ReadSingleBarcode

Header:	AVL.h
Namespace:	avl
Module:	Barcodes

Detects and recognizes a single barcode on the input image.

Applications: To be used as an easy all-in-one solution for typical barcode reading applications.

Syntax

void avl::ReadSingleBarcode
(
	const avl::Image& inImage,
	atl::Optional<const avl::Rectangle2D&> inRoi,
	atl::Optional<const avl::CoordinateSystem2D&> inRoiAlignment,
	atl::Optional<avl::BarcodeFormat::Type> inBarcodeFormat,
	float inMinGradientLength,
	int inBaseBarWidth,
	int inDetectionScanCount,
	const int inReadingScanCount,
	const int inScanWidth,
	const float inMinStrength,
	const float inSmoothingStdDev,
	avl::Polarity::Type inPolarity,
	atl::Conditional<avl::Rectangle2D>& outBarcodePosition,
	atl::Conditional<atl::String>& outDecodedText,
	atl::Conditional<avl::BarcodeFormat::Type>& outBarcodeFormat,
	atl::Optional<atl::Conditional<avl::Polarity::Type>&> outBarcodePolarity = atl::NIL,
	atl::Optional<avl::Rectangle2D&> outAlignedRoi = atl::NIL,
	atl::Optional<atl::Array<avl::Rectangle2D>&> outBarcodeCandidates = atl::NIL,
	avl::Image& diagGradientImage,
	atl::Array<avl::Segment2D>& diagScheduledScanSegments
)

Parameters

Name	Type	Range	Default	Description
inImage	const Image&			Input image
inRoi	Optional<const Rectangle2D&>		NIL	Region of interest
inRoiAlignment	Optional<const CoordinateSystem2D&>		NIL	Adjusts the region of interest to the position of the inspected object
inBarcodeFormat	Optional<BarcodeFormat::Type>		EAN13	Format of the barcode
inMinGradientLength	float	0.0 -	8.0f	Minimal gradient length of edge pixels used for detecting barcodes
inBaseBarWidth	int	1 -	3	Estimated width of the thinnest bar
inDetectionScanCount	int	1 -	5	Number of scan lines used in detecting barcode
inReadingScanCount	const int	1 -	5	Number of parallel scans run until first successful read
inScanWidth	const int	1 -	5	Width of the single scan
inMinStrength	const float	0.0 -	5.0f	Minimal strength of an extracted edge
inSmoothingStdDev	const float	0.0 -	0.25f	Standard deviation of the gaussian smoothing applied to the profile extracted in each scan
inPolarity	Polarity::Type		Dark	Specifies whether code is darker or brighter than the background
outBarcodePosition	Conditional<Rectangle2D>&			Position of the found barcode
outDecodedText	Conditional<String>&			Decoded barcode content or nothing if all of the scans failed
outBarcodeFormat	Conditional<BarcodeFormat::Type>&			Decoded barcode format or nothing if all of the scans failed
outBarcodePolarity	Optional<Conditional<Polarity::Type>&>		NIL	Decoded barcode polarity or nothing if all of the scans failed
outAlignedRoi	Optional<Rectangle2D&>		NIL	Input ROI after transformation (in the image coordinates)
outBarcodeCandidates	Optional<Array<Rectangle2D>&>		NIL	Places with high gradient values that are further investigated
diagGradientImage	Image&			Image of gradient directions
diagScheduledScanSegments	Array<Segment2D>&			Scheduled scan segments

Optional Outputs

The computation of following outputs can be switched off by passing value atl::NIL to these parameters: outBarcodePolarity, outAlignedRoi, outBarcodeCandidates.

Description

This filter works as a composition of DetectSingleBarcode and RecognizeBarcode filters.

Hints

Connect inImage with the output of your image acquisition filter.
Select inBarcodeFormat according to the type of codes you want to read. If you choose the wrong format, the codes will not be recognized. Setting its value to Auto can increase the computation time considerably. Furthermore, the Auto value causes detection of UPC-A codes as EAN-13 codes.

If the image quality is low, increase inMinGradientLength or increase inSmoothingStdDev. The diagGradientImage output shows how this affects an intermediate image.
If the image resolution is high, increase inBaseBarWidth or resize/downsample the input image.

Examples

Rotated barcode.

Low quality barcode printed on plastic foil.

Barcode on package wrapped in plastic foil.

Barcode in a blurry image.

Barcode on standard 330ml can.

Barcode on reflective and wrapped surface.

EAN-13 with add-on 2 used to indicate a book edition.

EAN-13 with add-on 5 to give a suggestion for the price.

Remarks

Minimal bar width requirement

To provide precise detection of the barcode width of the thinnest bar should be at least 1.5 pixels.

Depending on the barcode format guard or start/end code patterns must be readable.

Pharmacode usage

The pharmacode barcode type can be read correctly in both directions. To get results from both directions use a Pharmacode and PharmacodeInversed barcode types.

Before decoding a Pharmacode the code orientation angle is normalized to a range from -45° to 135° what makes the code decoding more stable

Results of reading using a different Pharmacode directions: Pharmacode = 23 and PharmacodeInversed = 16.

Using a relative coordinate systems

Read more about Local Coordinate Systems in Machine Vision Guide: Local Coordinate Systems.

Hardware Acceleration

This operation supports automatic parallelization for multicore and multiprocessor systems.