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ReadSingleDataMatrixCode

Header:	FIL.h
Namespace:	fil

Detects and recognizes one Data Matrix code.

Syntax

void fil::ReadSingleDataMatrixCode
(
	const fil::Image& inImage,
	ftl::Optional<const fil::Rectangle2D&> inRoi,
	ftl::Optional<const fil::CoordinateSystem2D&> inRoiAlignment,
	const fil::DataMatrixCodeParams& inCodeParams,
	const fil::DataMatrixDetectionParams& inDetectionParams,
	ftl::Conditional<fil::DataCode>& outDataMatrixCode,
	ftl::Array<fil::Path>& outCandidates,
	ftl::Optional<fil::Rectangle2D&> outAlignedRoi = ftl::NIL
)

Parameters

Name	Type	Default	Description
inImage	const Image&		Input image
inRoi	Optional<const Rectangle2D&>	NIL	Region of interest
inRoiAlignment	Optional<const CoordinateSystem2D&>	NIL	Coordinate system for the region of interest
inCodeParams	const DataMatrixCodeParams&		Specification of codes that can be detected
inDetectionParams	const DataMatrixDetectionParams&		Specification of the way the codes are being detected
outDataMatrixCode	Conditional<DataCode>&
outCandidates	Array<Path>&		Diagnostic information about detection results
outAlignedRoi	Optional<Rectangle2D&>	NIL	Input ROI after transformation (in the image coordinates)

Optional Outputs

The computation of following outputs can be switched off by passing value ftl::NIL to these parameters: outAlignedRoi.

Description

This filter detects and recognizes one data matrix code on an image.

Supported code types: ECC 200 and ECC 000-140.

Hints

Specify the range of possible codes on an image by setting the inCodeParams input. The more narrow is the specification, the faster the filter works.

Set inCodeParams.Polarity to specify whether dark-on-bright or bright-on-dark codes are to be read.
Specify the range of possible code sizes with inCodeParams.MinRowCount, inCodeParams.MaxRowCount, inCodeParams.MinColumnCount, inCodeParams.MinColumnCount.
Specify the range of possible module sizes (in pixels) with inCodeParams.MinModuleSize and inCodeParams.MaxModuleSize.
Set inCodeParams.ExpectedGapSize according to the following rules:
- Zero – no gaps at all (modules are fully filled).
- Small – gaps up to 25% of the module size.
- Medium – gaps up to 50% of the module size; it may require a bigger Quiet Zone.
- Large – gaps up to 75%; comes with no guarantee.
Modify inCodeParams.MaxRectangleRatio if you expect to work also with non-square codes. The value specifies maximal ratio between the length of the longer side to the length of the shorter side.

If some codes are not detected, try modifying inDetectionParams:

Increase inDetectionParams.ContrastThreshold if the noise is high. Decrease it, if the noise is low and the difference between the bright and the dark modules is low.
Use inDetectionParams.DynamicSNRatio if there is non uniform illumination or background contamination near the quiet zone.
Turn on inDetectionParams.NonBinarySegmentation if there are very dark or very bright pixels close to the quiet zone.
Choose "FinderPattern" value for inDetectionParams.DetectionMethod if the quiet zone can be distorted or contaminated.
Set inDetectionParams.PyramidStrategy to "Strict" if you want to increase reliability at the cost of higher execution time.