#include <string.h>
#include "allheaders.h"
#include "readbarcode.h"

Macros
#define	DEBUG_DESKEW 0

#define	DEBUG_WIDTHS 0

Functions
static PIX *	pixGenerateBarcodeMask (PIX *pixs, l_int32 maxspace, l_int32 nwidth, l_int32 nheight)

static NUMA *	pixAverageRasterScans (PIX *pixs, l_int32 nscans)

static l_int32	numaGetCrossingDistances (NUMA nas, NUMA pnaedist, NUMA pnaodist, l_float32 pmindist, l_float32 *pmaxdist)

static NUMA *	numaLocatePeakRanges (NUMA *nas, l_float32 minfirst, l_float32 minsep, l_float32 maxmin)

static NUMA *	numaGetPeakCentroids (NUMA nahist, NUMA narange)

static NUMA *	numaGetPeakWidthLUT (NUMA narange, NUMA nacent)

static l_int32	numaEvalBestWidthAndShift (NUMA nas, l_int32 nwidth, l_int32 nshift, l_float32 minwidth, l_float32 maxwidth, l_float32 pbestwidth, l_float32 pbestshift, l_float32 pbestscore)

static l_int32	numaEvalSyncError (NUMA nas, l_int32 ifirst, l_int32 ilast, l_float32 width, l_float32 shift, l_float32 pscore, NUMA **pnad)

SARRAY *	pixProcessBarcodes (PIX pixs, l_int32 format, l_int32 method, SARRAY *psaw, l_int32 debugflag)

PIXA *	pixExtractBarcodes (PIX *pixs, l_int32 debugflag)

SARRAY *	pixReadBarcodes (PIXA pixa, l_int32 format, l_int32 method, SARRAY *psaw, l_int32 debugflag)

NUMA *	pixReadBarcodeWidths (PIX *pixs, l_int32 method, l_int32 debugflag)

BOXA *	pixLocateBarcodes (PIX pixs, l_int32 thresh, PIX ppixb, PIX *ppixm)

PIX *	pixDeskewBarcode (PIX pixs, PIX pixb, BOX box, l_int32 margin, l_int32 threshold, l_float32 pangle, l_float32 *pconf)

NUMA *	pixExtractBarcodeWidths1 (PIX pixs, l_float32 thresh, l_float32 binfract, NUMA pnaehist, NUMA *pnaohist, l_int32 debugflag)

NUMA *	pixExtractBarcodeWidths2 (PIX pixs, l_float32 thresh, l_float32 pwidth, NUMA **pnac, l_int32 debugflag)

NUMA *	pixExtractBarcodeCrossings (PIX *pixs, l_float32 thresh, l_int32 debugflag)

NUMA *	numaQuantizeCrossingsByWidth (NUMA nas, l_float32 binfract, NUMA pnaehist, NUMA *pnaohist, l_int32 debugflag)

NUMA *	numaQuantizeCrossingsByWindow (NUMA nas, l_float32 ratio, l_float32 pwidth, l_float32 pfirstloc, NUMA *pnac, l_int32 debugflag)

Variables
static const l_int32	MAX_SPACE_WIDTH = 19

static const l_int32	MAX_NOISE_WIDTH = 50

static const l_int32	MAX_NOISE_HEIGHT = 30

static const l_int32	MIN_BC_WIDTH = 50

static const l_int32	MIN_BC_HEIGHT = 50

Detailed Description


     Basic operations to locate and identify the line widths
     in 1D barcodes.

     Top level
         SARRAY          *pixProcessBarcodes()

     Next levels
         PIXA            *pixExtractBarcodes()
         SARRAY          *pixReadBarcodes()
         l_int32          pixReadBarcodeWidths()

     Location
         BOXA            *pixLocateBarcodes()
         static PIX      *pixGenerateBarcodeMask()

     Extraction and deskew
         PIXA            *pixDeskewBarcodes()

     Process to get line widths
         NUMA            *pixExtractBarcodeWidths1()
         NUMA            *pixExtractBarcodeWidths2()
         NUMA            *pixExtractBarcodeCrossings()

     Average adjacent rasters
         static NUMA     *pixAverageRasterScans()

     Signal processing for barcode widths
         NUMA            *numaQuantizeCrossingsByWidth()
         static l_int32   numaGetCrossingDistances()
         static NUMA     *numaLocatePeakRanges()
         static NUMA     *numaGetPeakCentroids()
         static NUMA     *numaGetPeakWidthLUT()
         NUMA            *numaQuantizeCrossingsByWindow()
         static l_int32   numaEvalBestWidthAndShift()
         static l_int32   numaEvalSyncError()


 NOTE CAREFULLY: This is "early beta" code.  It has not been tuned
 to work robustly on a large database of barcode images.  I'm putting
 it out so that people can play with it, find out how it breaks, and
 contribute decoders for other barcode formats.  Both the functional
 interfaces and ABI will almost certainly change in the coming
 few months.  The actual decoder, in bardecode.c, at present only
 works on the following codes: Code I2of5, Code 2of5, Code 39, Code 93
 Codabar and UPCA.  To add another barcode format, it is necessary
 to make changes in readbarcode.h and bardecode.c.
 The program prog/barcodetest shows how to run from the top level
 (image --> decoded data).

Definition in file readbarcode.c.

Macro Definition Documentation

◆ DEBUG_DESKEW

#define DEBUG_DESKEW 0

Definition at line 123 of file readbarcode.c.

◆ DEBUG_WIDTHS

#define DEBUG_WIDTHS 0

Definition at line 124 of file readbarcode.c.

Function Documentation

◆ numaEvalBestWidthAndShift()

static l_int32 numaEvalBestWidthAndShift	(	NUMA *	nas,
		l_int32	nwidth,
		l_int32	nshift,
		l_float32	minwidth,
		l_float32	maxwidth,
		l_float32 *	pbestwidth,
		l_float32 *	pbestshift,
		l_float32 *	pbestscore )

static

numaEvalBestWidthAndShift()

Parameters

[in]	nas	numa of crossing locations
[in]	nwidth	number of widths to consider
[in]	nshift	number of shifts to consider for each width
[in]	minwidth	smallest width to consider
[in]	maxwidth	largest width to consider
[out]	pbestwidth	best size of window
[out]	pbestshift	best shift for the window
[out]	pbestscore	[optional] average squared error of dist of crossing signal from the center of the window

Returns: 0 if OK, 1 on error

Notes:
     (1) This does a linear sweep of widths, evaluating at nshift
         shifts for each width, finding the (width, shift) pair that
         gives the minimum score.

Definition at line 1379 of file readbarcode.c.

References numaEvalSyncError().

Referenced by numaQuantizeCrossingsByWindow().

◆ numaEvalSyncError()

static l_int32 numaEvalSyncError	(	NUMA *	nas,
		l_int32	ifirst,
		l_int32	ilast,
		l_float32	width,
		l_float32	shift,
		l_float32 *	pscore,
		NUMA **	pnad )

static

numaEvalSyncError()

Parameters

[in]	nas	numa of crossing locations
[in]	ifirst	first crossing to use
[in]	ilast	last crossing to use; use 0 for all crossings
[in]	width	size of window
[in]	shift	of center of window w/rt first crossing
[out]	pscore	[optional] average squared error of dist of crossing signal from the center of the window
[out]	pnad	[optional] numa of 1s and 0s for crossings

Returns: 0 if OK, 1 on error

Notes:
     (1) The score is computed only on the part of the signal from the
         ifirst to ilast crossings.  Use 0 for both of these to
         use all the crossings.  The score is normalized for
         the number of crossings and with half-width of the window.
     (2) The optional return nad is a sequence of 0s and 1s, where a '1'
         indicates a crossing in the window.

Definition at line 1451 of file readbarcode.c.

Referenced by numaEvalBestWidthAndShift(), and numaQuantizeCrossingsByWindow().

◆ numaGetCrossingDistances()

static l_int32 numaGetCrossingDistances	(	NUMA *	nas,
		NUMA **	pnaedist,
		NUMA **	pnaodist,
		l_float32 *	pmindist,
		l_float32 *	pmaxdist )

static

numaGetCrossingDistances()

Parameters

[in]	nas	numa of crossing locations
[out]	pnaedist	[optional] even distances between crossings
[out]	pnaodist	[optional] odd distances between crossings
[out]	pmindist	[optional] min distance between crossings
[out]	pmaxdist	[optional] max distance between crossings

Returns: 0 if OK, 1 on error

Definition at line 1001 of file readbarcode.c.

Referenced by numaQuantizeCrossingsByWidth(), and numaQuantizeCrossingsByWindow().

◆ numaGetPeakCentroids()

static NUMA * numaGetPeakCentroids	(	NUMA *	nahist,
		NUMA *	narange )

static

numaGetPeakCentroids()

Parameters

[in]	nahist	numa of histogram of crossing widths
[in]	narange	numa of ranges of x-values for the peaks in nahist

Returns: nad centroids for each peak found; max of 4, corresponding to 4 different barcode line widths, or NULL on error

Definition at line 1140 of file readbarcode.c.

Referenced by numaQuantizeCrossingsByWidth().

◆ numaGetPeakWidthLUT()

static NUMA * numaGetPeakWidthLUT	(	NUMA *	narange,
		NUMA *	nacent )

static

numaGetPeakWidthLUT()

Parameters

[in]	narange	numa of x-val ranges for the histogram width peaks
[in]	nacent	numa of centroids of each peak – up to 4

Returns: nalut lookup table from the width of a bar to one of the four integerized barcode units, or NULL on error

Notes:
     (1) This generates the lookup table that maps from a sequence of widths
         (in some units) to the integerized barcode units (1, 2, 3, 4),
         which are the output integer widths between transitions.
     (2) The smallest width can be lost in float roundoff.  To avoid
         losing it, we expand the peak range of the smallest width.

Definition at line 1189 of file readbarcode.c.

References L_NOCOPY.

Referenced by numaQuantizeCrossingsByWidth().

◆ numaLocatePeakRanges()

static NUMA * numaLocatePeakRanges	(	NUMA *	nas,
		l_float32	minfirst,
		l_float32	minsep,
		l_float32	maxmin )

static

numaLocatePeakRanges()

Parameters

[in]	nas	numa of histogram of crossing widths
[in]	minfirst	min location of center of first peak
[in]	minsep	min separation between peak range centers
[in]	maxmin	max allowed value for min histo value between peaks

Returns: nad ranges for each peak found, in pairs, or NULL on error

Notes:
     (1) Units of minsep are the index into nas.
         This puts useful constraints on peak-finding.
     (2) If maxmin == 0.0, the value of nas[i] must go to 0.0 (or less)
         between peaks.
     (3) All calculations are done in units of the index into nas.
         The resulting ranges are therefore integers.
     (4) The output nad gives pairs of range values for successive peaks.
         Any location [i] for which maxmin = nas[i] = 0.0 will NOT be
         included in a peak range.  This works fine for histograms where
         if nas[i] == 0.0, it means that there are no samples at [i].
     (5) For barcodes, when this is used on a histogram of barcode
         widths, use maxmin = 0.0.  This requires that there is at
         least one histogram bin corresponding to a width value between
         adjacent peak ranges that is unpopulated, making the separation
         of the histogram peaks unambiguous.

Definition at line 1089 of file readbarcode.c.

Referenced by numaQuantizeCrossingsByWidth().

◆ numaQuantizeCrossingsByWidth()

NUMA * numaQuantizeCrossingsByWidth	(	NUMA *	nas,
		l_float32	binfract,
		NUMA **	pnaehist,
		NUMA **	pnaohist,
		l_int32	debugflag )

numaQuantizeCrossingsByWidth()

Parameters

[in]	nas	numa of crossing locations, in pixel units
[in]	binfract	histo binsize as a fraction of minsize; e.g., 0.25
[out]	pnaehist	[optional] histo of even (black) bar widths
[out]	pnaohist	[optional] histo of odd (white) bar widths
[in]	debugflag	1 to generate plots of histograms of bar widths

Returns: nad sequence of widths, in unit sizes, or NULL on error

Notes:
     (1) This first computes the histogram of black and white bar widths,
         binned in appropriate units.  There should be well-defined
         peaks, each corresponding to a specific width.  The sequence
         of barcode widths (namely, the integers from the set {1,2,3,4})
         is returned.
     (2) The optional returned histograms are binned in width units
         that are inversely proportional to binfract.  For example,
         if binfract = 0.25, there are 4.0 bins in the distance of
         the width of the narrowest bar.

Definition at line 848 of file readbarcode.c.

References numaGetCrossingDistances(), numaGetPeakCentroids(), numaGetPeakWidthLUT(), and numaLocatePeakRanges().

Referenced by pixExtractBarcodeWidths1().

◆ numaQuantizeCrossingsByWindow()

NUMA * numaQuantizeCrossingsByWindow	(	NUMA *	nas,
		l_float32	ratio,
		l_float32 *	pwidth,
		l_float32 *	pfirstloc,
		NUMA **	pnac,
		l_int32	debugflag )

numaQuantizeCrossingsByWindow()

Parameters

[in]	nas	numa of crossing locations
[in]	ratio	of max window size over min window size in search; typ. 2.0
[out]	pwidth	[optional] best window width
[out]	pfirstloc	[optional] center of window for first xing
[out]	pnac	[optional] array of window crossings (0, 1, 2)
[in]	debugflag	1 to generate various plots of intermediate results

Returns: nad sequence of widths, in unit sizes, or NULL on error

Notes:
     (1) The minimum size of the window is set by the minimum
         distance between zero crossings.
     (2) The optional return signal nac is a sequence of 0s, 1s,
         and perhaps a few 2s, giving the number of crossings in each window.
         On the occasion where there is a '2', it is interpreted as
         ending two runs: the previous one and another one that has length 1.

Definition at line 1279 of file readbarcode.c.

References numaEvalBestWidthAndShift(), numaEvalSyncError(), and numaGetCrossingDistances().

Referenced by pixExtractBarcodeWidths2().

◆ pixAverageRasterScans()

static NUMA * pixAverageRasterScans	(	PIX *	pixs,
		l_int32	nscans )

static

pixAverageRasterScans()

Parameters

[in]	pixs	input image; 8 bpp
[in]	nscans	number of adjacent scans, about the center vertically

Returns: numa of average pixel values across image, or NULL on error

Definition at line 782 of file readbarcode.c.

References GET_DATA_BYTE, and L_NOCOPY.

Referenced by pixExtractBarcodeCrossings().

◆ pixDeskewBarcode()

PIX * pixDeskewBarcode	(	PIX *	pixs,
		PIX *	pixb,
		BOX *	box,
		l_int32	margin,
		l_int32	threshold,
		l_float32 *	pangle,
		l_float32 *	pconf )

pixDeskewBarcode()

Parameters

[in]	pixs	input image; 8 bpp
[in]	pixb	binarized edge-filtered input image
[in]	box	identified region containing barcode
[in]	margin	of extra pixels around box to extract
[in]	threshold	for binarization; ~20
[out]	pangle	[optional] in degrees, clockwise is positive
[out]	pconf	[optional] confidence

Returns: pixd deskewed barcode, or NULL on error

Notes:
    (1) The (optional) angle returned is the angle in degrees (cw positive)
        necessary to rotate the image so that it is deskewed.

Definition at line 500 of file readbarcode.c.

References L_BRING_IN_WHITE, L_CLONE, L_ROTATE_AREA_MAP, L_SORT_BY_AREA, L_SORT_DECREASING, and pixLocateBarcodes().

Referenced by pixExtractBarcodes().

◆ pixExtractBarcodeCrossings()

NUMA * pixExtractBarcodeCrossings	(	PIX *	pixs,
		l_float32	thresh,
		l_int32	debugflag )

pixExtractBarcodeCrossings()

Parameters

[in]	pixs	input image; 8 bpp
[in]	thresh	estimated pixel threshold for crossing white <--> black; typ. ~120
[in]	debugflag	use 1 to generate debug output

Returns: numa of crossings, in pixel units, or NULL on error

Notes:
     (1) Require at least 10 crossings.

Definition at line 722 of file readbarcode.c.

References L_QUADRATIC_INTERP, and pixAverageRasterScans().

Referenced by pixExtractBarcodeWidths1(), and pixExtractBarcodeWidths2().

◆ pixExtractBarcodes()

PIXA * pixExtractBarcodes	(	PIX *	pixs,
		l_int32	debugflag )

pixExtractBarcodes()

Parameters

[in]	pixs	8 bpp, no colormap
[in]	debugflag	use 1 to generate debug output

Returns: pixa deskewed and cropped barcodes, or NULL if none found or on error

Definition at line 186 of file readbarcode.c.

References L_CLONE, L_INSERT, pixDeskewBarcode(), and pixLocateBarcodes().

Referenced by pixProcessBarcodes().

◆ pixExtractBarcodeWidths1()

NUMA * pixExtractBarcodeWidths1	(	PIX *	pixs,
		l_float32	thresh,
		l_float32	binfract,
		NUMA **	pnaehist,
		NUMA **	pnaohist,
		l_int32	debugflag )

pixExtractBarcodeWidths1()

Parameters

[in]	pixs	input image; 8 bpp
[in]	thresh	estimated pixel threshold for crossing white <--> black; typ. ~120
[in]	binfract	histo binsize as a fraction of minsize; e.g., 0.25
[out]	pnaehist	[optional] histogram of black widths; NULL ok
[out]	pnaohist	[optional] histogram of white widths; NULL ok
[in]	debugflag	use 1 to generate debug output

Returns: nad numa of barcode widths in encoded integer units, or NULL on error

Notes:
    (1) The widths are alternating black/white, starting with black
        and ending with black.
    (2) This method uses the widths of the bars directly, in terms
        of the (float) number of pixels between transitions.
        The histograms of these widths for black and white bars is
        generated and interpreted.

Definition at line 628 of file readbarcode.c.

References numaQuantizeCrossingsByWidth(), and pixExtractBarcodeCrossings().

Referenced by pixReadBarcodeWidths().

◆ pixExtractBarcodeWidths2()

NUMA * pixExtractBarcodeWidths2	(	PIX *	pixs,
		l_float32	thresh,
		l_float32 *	pwidth,
		NUMA **	pnac,
		l_int32	debugflag )

pixExtractBarcodeWidths2()

Parameters

[in]	pixs	input image; 8 bpp
[in]	thresh	estimated pixel threshold for crossing white <--> black; typ. ~120
[out]	pwidth	[optional] best decoding window width, in pixels
[out]	pnac	[optional] number of transitions in each window
[in]	debugflag	use 1 to generate debug output

Returns: nad numa of barcode widths in encoded integer units, or NULL on error

Notes:
     (1) The widths are alternating black/white, starting with black
         and ending with black.
     (2) The optional best decoding window width is the width of the window
         that is used to make a decision about whether a transition occurs.
         It is approximately the average width in pixels of the narrowest
         white and black bars (i.e., those corresponding to unit width).
     (3) The optional return signal nac is a sequence of 0s, 1s,
         and perhaps a few 2s, giving the number of crossings in each window.
         On the occasion where there is a '2', it is interpreted as
         as ending two runs: the previous one and another one that has length 1.

Definition at line 682 of file readbarcode.c.

References numaQuantizeCrossingsByWindow(), and pixExtractBarcodeCrossings().

Referenced by pixReadBarcodeWidths().

◆ pixGenerateBarcodeMask()

static PIX * pixGenerateBarcodeMask	(	PIX *	pixs,
		l_int32	maxspace,
		l_int32	nwidth,
		l_int32	nheight )

static

pixGenerateBarcodeMask()

Parameters

[in]	pixs	1 bpp
[in]	maxspace	largest space in the barcode, in pixels
[in]	nwidth	opening 'width' to remove noise
[in]	nheight	opening 'height' to remove noise

Returns: pixm mask over barcodes, or NULL if none found or on error

Notes:
     (1) For noise removal, 'width' and 'height' are referred to the
         barcode orientation.
     (2) If there is skew, the mask will not cover the barcode corners.

Definition at line 446 of file readbarcode.c.

Referenced by pixLocateBarcodes().

◆ pixLocateBarcodes()

BOXA * pixLocateBarcodes	(	PIX *	pixs,
		l_int32	thresh,
		PIX **	ppixb,
		PIX **	ppixm )

pixLocateBarcodes()

Parameters

[in]	pixs	any depth
[in]	thresh	for binarization of edge filter output; typ. 20
[out]	ppixb	[optional] binarized edge filtered input image
[out]	ppixm	[optional] mask over barcodes

Returns: boxa location of barcodes, or NULL if none found or on error

Definition at line 388 of file readbarcode.c.

References L_ALL_EDGES, and pixGenerateBarcodeMask().

Referenced by pixDeskewBarcode(), and pixExtractBarcodes().

◆ pixProcessBarcodes()

SARRAY * pixProcessBarcodes	(	PIX *	pixs,
		l_int32	format,
		l_int32	method,
		SARRAY **	psaw,
		l_int32	debugflag )

pixProcessBarcodes()

Parameters

[in]	pixs	any depth
[in]	format	L_BF_ANY, L_BF_CODEI2OF5, L_BF_CODE93, ...
[in]	method	L_USE_WIDTHS, L_USE_WINDOWS
[out]	psaw	[optional] sarray of bar widths
[in]	debugflag	use 1 to generate debug output

Returns: sarray text of barcodes, or NULL if none found or on error

Definition at line 142 of file readbarcode.c.

References pixExtractBarcodes(), and pixReadBarcodes().

◆ pixReadBarcodes()

SARRAY * pixReadBarcodes	(	PIXA *	pixa,
		l_int32	format,
		l_int32	method,
		SARRAY **	psaw,
		l_int32	debugflag )

pixReadBarcodes()

Parameters

[in]	pixa	of 8 bpp deskewed and cropped barcodes
[in]	format	L_BF_ANY, L_BF_CODEI2OF5, L_BF_CODE93, ...
[in]	method	L_USE_WIDTHS, L_USE_WINDOWS;
[out]	psaw	[optional] sarray of bar widths
[in]	debugflag	use 1 to generate debug output

Returns: sa sarray of widths, one string for each barcode found, or NULL on error

Definition at line 257 of file readbarcode.c.

References L_CLONE, L_COPY, L_INSERT, and pixReadBarcodeWidths().

Referenced by pixProcessBarcodes().

◆ pixReadBarcodeWidths()

NUMA * pixReadBarcodeWidths	(	PIX *	pixs,
		l_int32	method,
		l_int32	debugflag )

pixReadBarcodeWidths()

Parameters

[in]	pixs	of 8 bpp deskewed and cropped barcode
[in]	method	L_USE_WIDTHS, L_USE_WINDOWS;
[in]	debugflag	use 1 to generate debug output

Returns: na numa of widths (each in set {1,2,3,4}, or NULL on error

Definition at line 341 of file readbarcode.c.

References pixExtractBarcodeWidths1(), and pixExtractBarcodeWidths2().

Referenced by pixReadBarcodes().

Variable Documentation

◆ MAX_NOISE_HEIGHT

const l_int32 MAX_NOISE_HEIGHT = 30

static

Definition at line 94 of file readbarcode.c.

◆ MAX_NOISE_WIDTH

const l_int32 MAX_NOISE_WIDTH = 50

static

Definition at line 93 of file readbarcode.c.

◆ MAX_SPACE_WIDTH

const l_int32 MAX_SPACE_WIDTH = 19

static

Definition at line 92 of file readbarcode.c.

◆ MIN_BC_HEIGHT

const l_int32 MIN_BC_HEIGHT = 50

static

Definition at line 98 of file readbarcode.c.

◆ MIN_BC_WIDTH

const l_int32 MIN_BC_WIDTH = 50

static

Definition at line 97 of file readbarcode.c.

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ DEBUG_DESKEW

◆ DEBUG_WIDTHS

Function Documentation

◆ numaEvalBestWidthAndShift()

◆ numaEvalSyncError()

◆ numaGetCrossingDistances()

◆ numaGetPeakCentroids()

◆ numaGetPeakWidthLUT()

◆ numaLocatePeakRanges()

◆ numaQuantizeCrossingsByWidth()

◆ numaQuantizeCrossingsByWindow()

◆ pixAverageRasterScans()

◆ pixDeskewBarcode()

◆ pixExtractBarcodeCrossings()

◆ pixExtractBarcodes()

◆ pixExtractBarcodeWidths1()

◆ pixExtractBarcodeWidths2()

◆ pixGenerateBarcodeMask()

◆ pixLocateBarcodes()

◆ pixProcessBarcodes()

◆ pixReadBarcodes()

◆ pixReadBarcodeWidths()

Variable Documentation

◆ MAX_NOISE_HEIGHT

◆ MAX_NOISE_WIDTH

◆ MAX_SPACE_WIDTH

◆ MIN_BC_HEIGHT

◆ MIN_BC_WIDTH