WebCam as BarCode Reader

[andybiochem]

WebCam as BarCode Reader

===================

This is a project I've just started to try to get my webcam to recognise barcodes.

Eventually I hope to be able to get the script to automatically detect barcodes of

any type, and quickly return the encoded text.

Ok, first some disclaimers:

1) This only works with simple CODE128 barcodes in code C at the moment.

2) It is not 100% effective, I get 1 in 5 reads as successful.

3) Upon exit, sometimes the script hangs (anyone know what I'm doing wrong???)

Consider this very much a work-in-progress.

Example useage:

This is a barcode I created using my Barcode Generator (see sig) and then printed out :

Note: the text in the barcode is "123456"

This is how it looks in the GUI having successfully 'read' the barcode:

expandcollapse popup

#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <StaticConstants.au3>
#include <Array.au3>
#Include <Color.au3>

Opt("GUIOnEventMode",1)
Opt("PixelCoordMode",2)

HotKeySet("{F1}","_Cap")

;************************************************
; Variables
;************************************************




;----- Open DLLs ----- 
$dAviCap32 = DllOpen("avicap32.dll")
$dUser32 = DllOpen("user32.dll")

;----- Arrays -----
Global $aPixels[321]
Global $aLabels[321]
Global $aSplit[1]

Global $aBC128[104]
$aBC128[1] = "0¬ ¬00¬11011001100"
$aBC128[2] = "1¬!¬01¬11001101100"
$aBC128[3] = '2¬"¬02¬11001100110'
$aBC128[4] = "3¬#¬03¬10010011000"
$aBC128[5] = "4¬$¬04¬10010001100"
$aBC128[6] = "5¬%¬05¬10001001100"
$aBC128[7] = "6¬&¬06¬10011001000"
$aBC128[8] = "7¬'¬07¬10011000100"
$aBC128[9] = "8¬(¬08¬10001100100"
$aBC128[10] = "9¬)¬09¬11001001000"
$aBC128[11] = "10¬*¬10¬11001000100"
$aBC128[12] = "11¬+¬11¬11000100100"
$aBC128[13] = "12¬,¬12¬10110011100"
$aBC128[14] = "13¬-¬13¬10011011100"
$aBC128[15] = "14¬.¬14¬10011001110"
$aBC128[16] = "15¬/¬15¬10111001100"
$aBC128[17] = "16¬0¬16¬10011101100"
$aBC128[18] = "17¬1¬17¬10011100110"
$aBC128[19] = "18¬2¬18¬11001110010"
$aBC128[20] = "19¬3¬19¬11001011100"
$aBC128[21] = "20¬4¬20¬11001001110"
$aBC128[22] = "21¬5¬21¬11011100100"
$aBC128[23] = "22¬6¬22¬11001110100"
$aBC128[24] = "23¬7¬23¬11101101110"
$aBC128[25] = "24¬8¬24¬11101001100"
$aBC128[26] = "25¬9¬25¬11100101100"
$aBC128[27] = "26¬:¬26¬11100100110"
$aBC128[28] = "27¬;¬27¬11101100100"
$aBC128[29] = "28¬<¬28¬11100110100"
$aBC128[30] = "29¬=¬29¬11100110010"
$aBC128[31] = "30¬>¬30¬11011011000"
$aBC128[32] = "31¬?¬31¬11011000110"
$aBC128[33] = "32¬@¬32¬11000110110"
$aBC128[34] = "33¬A¬33¬10100011000"
$aBC128[35] = "34¬B¬34¬10001011000"
$aBC128[36] = "35¬C¬35¬10001000110"
$aBC128[37] = "36¬D¬36¬10110001000"
$aBC128[38] = "37¬E¬37¬10001101000"
$aBC128[39] = "38¬F¬38¬10001100010"
$aBC128[40] = "39¬G¬39¬11010001000"
$aBC128[41] = "40¬H¬40¬11000101000"
$aBC128[42] = "41¬I¬41¬11000100010"
$aBC128[43] = "42¬J¬42¬10110111000"
$aBC128[44] = "43¬K¬43¬10110001110"
$aBC128[45] = "44¬L¬44¬10001101110"
$aBC128[46] = "45¬M¬45¬10111011000"
$aBC128[47] = "46¬N¬46¬10111000110"
$aBC128[48] = "47¬O¬47¬10001110110"
$aBC128[49] = "48¬P¬48¬11101110110"
$aBC128[50] = "49¬Q¬49¬11010001110"
$aBC128[51] = "50¬R¬50¬11000101110"
$aBC128[52] = "51¬S¬51¬11011101000"
$aBC128[53] = "52¬T¬52¬11011100010"
$aBC128[54] = "53¬U¬53¬11011101110"
$aBC128[55] = "54¬V¬54¬11101011000"
$aBC128[56] = "55¬W¬55¬11101000110"
$aBC128[57] = "56¬X¬56¬11100010110"
$aBC128[58] = "57¬Y¬57¬11101101000"
$aBC128[59] = "58¬Z¬58¬11101100010"
$aBC128[60] = "59¬[¬59¬11100011010"
$aBC128[61] = "60¬\¬60¬11101111010"
$aBC128[62] = "61¬]¬61¬11001000010"
$aBC128[63] = "62¬^¬62¬11110001010"
$aBC128[64] = "63¬_¬63¬10100110000"
$aBC128[65] = "64¬`¬64¬10100001100"
$aBC128[66] = "65¬a¬65¬10010110000"
$aBC128[67] = "66¬b¬66¬10010000110"
$aBC128[68] = "67¬c¬67¬10000101100"
$aBC128[69] = "68¬d¬68¬10000100110"
$aBC128[70] = "69¬e¬69¬10110010000"
$aBC128[71] = "70¬f¬70¬10110000100"
$aBC128[72] = "71¬g¬71¬10011010000"
$aBC128[73] = "72¬h¬72¬10011000010"
$aBC128[74] = "73¬i¬73¬10000110100"
$aBC128[75] = "74¬j¬74¬10000110010"
$aBC128[76] = "75¬k¬75¬11000010010"
$aBC128[77] = "76¬l¬76¬11001010000"
$aBC128[78] = "77¬m¬77¬11110111010"
$aBC128[79] = "78¬n¬78¬11000010100"
$aBC128[80] = "79¬o¬79¬10001111010"
$aBC128[81] = "80¬p¬80¬10100111100"
$aBC128[82] = "81¬q¬81¬10010111100"
$aBC128[83] = "82¬r¬82¬10010011110"
$aBC128[84] = "83¬s¬83¬10111100100"
$aBC128[85] = "84¬t¬84¬10011110100"
$aBC128[86] = "85¬u¬85¬10011110010"
$aBC128[87] = "86¬v¬86¬11110100100"
$aBC128[88] = "87¬w¬87¬11110010100"
$aBC128[89] = "88¬x¬88¬11110010010"
$aBC128[90] = "89¬y¬89¬11011011110"
$aBC128[91] = "90¬z¬90¬11011110110"
$aBC128[92] = "91¬{¬91¬11110110110"
$aBC128[93] = "92¬|¬92¬10101111000"
$aBC128[94] = "93¬}¬93¬10100011110"
$aBC128[95] = "94¬~¬94¬10001011110"
$aBC128[96] = "95¬del¬95¬10111101000"
$aBC128[97] = "96¬Fnc3¬96¬10111100010"
$aBC128[98] = "97¬Fnc2¬97¬11110101000"
$aBC128[99] = "98¬Shift¬98¬11110100010"
$aBC128[100] = "99¬Code C¬99¬10111011110"
$aBC128[101] = "100¬Fnc 4¬Code B¬10111101110"
$aBC128[102] = "101¬Code A¬Code A¬11101011110"
$aBC128[103] = "102¬Fnc 1¬Fnc 1¬11110101110"



;************************************************
; GUI
;************************************************

$GUI = GUICreate("",350,200)
GUISetOnEvent($GUI_EVENT_CLOSE,"_Close")



;************************************************
; WebCam
;************************************************

$dWebCam = DllCall($dAviCap32,"int","capCreateCaptureWindow","str","cap","int", _ 
BitOR($WS_CHILD,$WS_VISIBLE),"int",15,"int",15,"int",320,"int",50,"hwnd",$GUI,"int",1)
DllCall($dUser32,"int","SendMessage","hWnd",$dWebCam[0],"int",0x400 + 10,"int",0,"int",0)
DllCall($dUser32,"int","SendMessage","hWnd",$dWebCam[0],"int",0x400 + 50,"int",1,"int",0)
DllCall($dUser32,"int","SendMessage","hWnd",$dWebCam[0],"int",0x400 + 52,"int",1,"int",0)


;************************************************
; Labels
;************************************************

For $i = 1 to 320
    If IsInt($i / 50) Then
        $aLabels[$i] = GUICtrlCreateLabel("",14 + $i,80,1,10)
    Else
        $aLabels[$i] = GUICtrlCreateLabel("",14 + $i,80,1,5)
    EndIf
    GUICtrlSetBkColor(-1,0x000000)
Next

$interpretation = GUICtrlCreateLabel("",15,130,320,15)





GUISetState(@SW_SHOW)
;################################################################
; LOOP
;################################################################
While 1
    Sleep(100)
Wend
;################################################################
; END LOOP
;################################################################



Func _Cap()
    
;----- Stop WebCam -----
    DllCall($dUser32,"int","SendMessage","hWnd",$dWebCam[0],"int",0x400 + 52,"int",0,"int",0)
    
;----- Get pixels across center -----
    $sString = ""
    For $i = 1 to 320
        $aPixels[$i] = PixelGetColor(14 + $i, 15 + 25)
        GUICtrlSetBkColor($aLabels[$i], $aPixels[$i])
        If _ColorGetRed($aPixels[$i]) > 100 Then
            $sString &= 0
        Else
            $sString &= 1
        EndIf
    Next
    
;_ArrayDisplay($aPixels)
    
;----- split up -----
    $sString = StringReplace($sString,"10","1|0")
    $sString = StringReplace($sString,"01","0|1")
    
    $aSplit = StringSplit($sString,"|")
    
;----- get wdith -----
    $iWidth = StringLen($aSplit[2]) / 2
    
;----- apply width -----
    For $i = 1 to (UBound($aSplit) - 1)
        
        $iDiv = StringLen($aSplit[$i]) / $iWidth
        
        Select
            Case $iDiv <= 1.4
                $iDiv = 1
            Case $iDiv >= 2.5
                $iDiv = 3
            Case Else
                $iDiv = 2
        EndSelect
        
        $aSplit[$i] = $iDiv
        
    Next

;_ArrayDisplay($aSplit)
    
;----- keep only code -----
    _ArrayPop($aSplit)
    _ArrayDelete($aSplit,1)
    
;_ArrayDisplay($aSplit)
    
;----- build 1/0 code -----
    $sCode = ""
    $iBool = 1
    For $i = 1 to (UBound($aSplit) - 1)
        
        For $j = 1 to $aSplit[$i]
            $sCode &= $iBool
        Next
        
        If $iBool = 1 Then
            $iBool = 0
        Else
            $iBool = 1
        EndIf
    
    Next
    
;----- Split into array -----
    Dim $aSplit[1]
    For $i = 1 To StringLen($sCode)
        If IsInt($i / 11) Then _ArrayAdd($aSplit,StringMid($sCode,$i - 10,11))
    Next
    
;----- search barcode array -----
    $sCode = ""
    For $i = 1 to (UBound($aSplit) - 1)
        For $j = 1 to 103
            $aData = StringSplit($aBC128[$j],"¬")
            
            If $aSplit[$i] = $aData[4] Then $sCode &= $aData[3]
        Next
    Next
    
;----- display text -----
    GUICtrlSetData($interpretation,"Barcode text = " & StringTrimRight($sCode,2))
    
;----- Start WebCam -----
    DllCall($dUser32,"int","SendMessage","hWnd",$dWebCam[0],"int",0x400 + 52,"int",1,"int",0)
    

EndFunc





Func _Close()
;************************************************
; Exit
;************************************************
    DllCall($dUser32,"int","SendMessage","hWnd",$dWebCam[0],"int",0x400 + 181,"int",0,"int",0)
    DllCall($dUser32,"int","SendMessage","hWnd",$dWebCam[0],"int",0x400 + 11,"int",0,"int",0)
    DllClose($dUser32)
    DllClose($dAviCap32)
    
    Exit
    
EndFunc

Credits go to Rysiora for the basic DLL calls to get the WebCam in the GUI:

http://www.autoitscript.com/forum/index.ph...5&hl=webcam

Have fun.

Edited February 3, 2009 by andybiochem

[youknowwho4eva]

I was planning on maybe one day thinking about doing this, but I stopped with what i had made, where you take an image and click on the left then on the right and it read it. The hardest part is pixelation.

http://www.autoitscript.com/forum/index.ph...c=84239&hl=

[martin]

Looks interesting andbiochem, though I haven't tried it yet.

Arte you planning to be able to work out if the image needs to be rotated?

Why do think the reliability is not so good at the moment? (Looks like the result from the webcam is better than the original printout, is the print resolution the problem?)

[andybiochem]

I was planning on maybe one day thinking about doing this, but I stopped with what i had made, where you take an image and click on the left then on the right and it read it. The hardest part is pixelation.

Yeah, I saw your post (good job btw), but I thought this was significantly different and worth the post.

Looks interesting andbiochem, though I haven't tried it yet.

Arte you planning to be able to work out if the image needs to be rotated?

Why do think the reliability is not so good at the moment? (Looks like the result from the webcam is better than the original printout, is the print resolution the problem?)

'Rotated' as in upside-down? Hmmm, good point... hadn't thought about that to be honest.

Reliability not so good due to a couple of things:

1) each individual line's width (be it black or white) can be 1, 2, or 3 pixels. In Code128 the first 'bar' is 2 pixels wide, and in my algorithm I'm just dividing the detected number of pixels of the 1st line by 2 to get the 'single' bar width. This works well IF the cam is perfectly perpendicular to the page. If the barcode actually forms some sort of other shape other than rectangular (i.e. 4 x 90 right angles), then the algo fails somewhat. A good fix might be to read the 1st and last lines and check for equality in width and height, and only allow 'reading' when equality occurs.

2) my webcam is rubbish, and so resolution is not great. I'm suprised it works AT ALL.

Print resolution is spot on. The image of the printout is from the webcam too!

Edited February 3, 2009 by andybiochem

[martin]

Print resolution is spot on. The image of the printout is from the webcam too!

I hadn't thought of that.

[Lee Evans]

Very interesting project this one. I can imagine a whole host of possibilitys with databases etc. Give me all the unique barcode ids for CD and books etc that could then be looked up in other databases online perhaps.

[youknowwho4eva]

Don't get me wrong, I wasn't saying mine was better or worse or anything. I just figured if you hadn't seen it I could save you some work.

[andybiochem]

Don't get me wrong, I wasn't saying mine was better or worse or anything.

Don't worry I didn't think that, just like I said; our algos are quite different, and I wanted a system that would act like your typical supermarket cashier barcode reader, i.e. you just 'wave' the barcode in front of the reader (in this case a webcam), and then it automatically picks up and translates the code to string.

This project has got me thinking about the possibilities of using a webcam in autoit, you could have face-recognition, motion detection (I know there's a thread on this already), barcode readers, OCR, etc.

AutoIt is ace.

[martin]

With the rotation comment I made in post #3 I was thinking about how you would deal with the barcode being at any angle. If it was at 45 degrees then you would have a problem reading it wouldn't you? If it is completely upside down then you can just try scanning left to right and then right to left to see which way gives a valid code.

I wondered about how to deal with the angle, assuming it is a problem.

You could check every pixel along a line and every time you find a pixel which is black you count up 1. So you end up with an value for every line. If the code is lined up correctly the values would be something like 0,0,0,100,100,100,100,0,0,0 say. But if it's at an angle you will get 0,1,3,10,30,50,80,60,40,30,10,0 maybe. So you rotate untill you get as near as you can to sudden change to a fixed value and a sudden change to nothing again.

Or, you scan along a line until you hit a black pixel. Then you find the next pixel which is adjacent and also next to a white pixel. With a few conditions you should be able to pick out the edge of a line at the end of the code. Once you have that you can decide the best straight line through those points and get the angle. Maybe related to finding outlines.

[youknowwho4eva]

I was thinking of something where your background is a feed from your web cam and to open folders and such you point at them. but it would be hard to configure and harder to get it to recognize you pointing at something

[andybiochem]

With the rotation comment I made in post #3 I was thinking about how you would deal with the barcode being at any angle. If it was at 45 degrees then you would have a problem reading it wouldn't you? If it is completely upside down then you can just try scanning left to right and then right to left to see which way gives a valid code.

I wondered about how to deal with the angle, assuming it is a problem.

oh ok, I misunderstood. I'm not sure if it's really a problem to be honest, for the following reason; most commercial barcode scanners also require that the barcode is parallel to the reading sensor. Perhaps it's possible like you said, but I think maybe it'd be wasted effort. I don't think it would be too much of a hassle to get the user to align the barcode to the webcam properly.

The current script allows a certain degree of rotation anyway, as long as all the bars are visible along a straight line.

e.g. Both these barcodes will be read successfully (the red line is the 'reading plane'):

[martin]

oh ok, I misunderstood. I'm not sure if it's really a problem to be honest, for the following reason; most commercial barcode scanners also require that the barcode is parallel to the reading sensor. Perhaps it's possible like you said, but I think maybe it'd be wasted effort. I don't think it would be too much of a hassle to get the user to align the barcode to the webcam properly.

The current script allows a certain degree of rotation anyway, as long as all the bars are visible along a straight line.

e.g. Both these barcodes will be read successfully (the red line is the 'reading plane'):

OK, in fact maybe the one at 45 degrees can be read more accurately because the code is spread over a few more pixels.

[TheSaint]

@andybiochem

Good work, keep at it!

You've just given me another reason to get a WebCam.

Thanks for sharing!

[wiegandweitz]

To get better results, I suggest a statistical approach:

- reading the barcode x times, if 70/80/90% percent come back with the same result, the result will be pretty reliable. If it comes to 40/50/60% the result is unspecific.

- considering the many webcams there are, u might want the user to choose x and percentage.

The problem of the angle towards the object maybe solved by - but this is only a wild guess - if u look for the sum of the bars as a complete picture. You know it is rectangular so you maybe come up with a solution to counter a strange angle with a single algorythm.

ciao, Wiegand

[Andrey777]

Where can I get get avicap32.dll ? I got some file "avicap32.dll", but have ERROR

D:\au3\webcam.au3(78,91) : WARNING: $WS_CHILD: possibly used before declaration.
$cap = DllCall($avi, "int", "capCreateCaptureWindow", "str", "cap", "int", BitOR($WS_CHILD,
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
D:\systeming\autosale\webcam.au3(78,103) : WARNING: $WS_VISIBLE: possibly used before declaration.
$cap = DllCall($avi, "int", "capCreateCaptureWindow", "str", "cap", "int", BitOR($WS_CHILD,$WS_VISIBLE)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


~~^
D:\systeming\autosale\webcam.au3(78,91) : ERROR: $WS_CHILD: undeclared global variable.
$cap = DllCall($avi, "int", "capCreateCaptureWindow", "str", "cap", "int", BitOR($WS_CHILD,
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
D:\systeming\autosale\webcam.au3 - 1 error(s), 2 warning(s)

Edited February 17, 2009 by Andrey777

[BrettF]

Hi,

They are different errors. Try to read them

Make sure you have this line in your script:

#include <WindowsConstants.au3>

Cheers,

Brett

[Andrey777]

Thank you! My question was about http://www.autoitscript.com/forum/index.ph...5&hl=webcam . And I solved my problem with your help.

I needn't get barcodes. But do not this script read barcode. Video was clear-cut. I much more times clicked F1 and seed image in first post.

Edited February 17, 2009 by Andrey777

[andybiochem]

To get better results, I suggest a statistical approach:

- reading the barcode x times, if 70/80/90% percent come back with the same result, the result will be pretty reliable. If it comes to 40/50/60% the result is unspecific.

- considering the many webcams there are, u might want the user to choose x and percentage.

The problem of the angle towards the object maybe solved by - but this is only a wild guess - if u look for the sum of the bars as a complete picture. You know it is rectangular so you maybe come up with a solution to counter a strange angle with a single algorythm.

ciao, Wiegand

The end reliability of the barcode content will always be 100% correct once I introduce the check-digit step (all barcodes end in a modulus based checking character to ensure that the scan was made correctly).

However, before I did this I wanted to make sure that the underlying 'reading' worked ok...which it doesn't, yet.

[Kip]

C:\Documents and Settings\HP_Administrator\Bureaublad\AutoIt\Nieuw - AutoIt v3 Script.au3 (213) : ==> Array variable has incorrect number of subscripts or subscript dimension range exceeded.:

$iWidth = StringLen($aSplit[2]) / 2

$iWidth = StringLen(^ ERROR

[The-dude]

I'm using a plug and play USB camera and I get the following result. The camera works just fine with other programs and I haven't needed to install any driver files.