DataMatrix recognition sometimes fails

Discussions about datamatrix barcode reading and writing
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martib
Posts: 1
Joined: Thu Sep 15, 2011 10:14 pm

DataMatrix recognition sometimes fails

Post by martib » Thu Sep 15, 2011 10:53 pm

Hi

I'm actually testing your DataMatrix Engine.
Based on scanned 300dpi multipage PDF Files I do a search on every whole page (no zonal reading).
In about 98% of all readings the code is successful. But on some of the pages it fails.
I tried to work with the rendering resolution 72, 200 and in a second try it works. Changing from 72 to 200 and vice versa.
Do you have any idea what's the reason for this behaviour? Shall I render each page twice which is not readable with 72 DPI?
The barcode is created by ID Automation's DataMatrix encoder and should be ok.

Here how my/your cod looks like. Most of them is from your example.

Code: Select all

                      PageCount = oPDF.GetPageCount
                                For i = 1 To PageCount
                                oPDF.SelectPage(i) 'Selecting page
                                m_ImageID = oPDF.RenderPageToGdPictureImage(72, False)
                                Application.DoEvents()
                                If m_ImageID <> 0 Then
                                    oGdPictureImaging.BarcodeDataMatrixReaderDoScan(m_ImageID)
                                    bcfound = oGdPictureImaging.BarcodeDataMatrixReaderGetBarcodeCount
                                    oGdPictureImaging.ReleaseGdPictureImage(m_ImageID)
                                    If bcfound > 0 Then
                                        For j = 1 To oGdPictureImaging.BarcodeDataMatrixReaderGetBarcodeCount
                                            BCWert = oGdPictureImaging.BarcodeDataMatrixReaderGetBarcodeValue(j).ToString
                                        Next

If you need some example of Documents I can only provide you with separator pages to your e-mail adress because those testfiles I'm using are confidential (with customer name on it)

Anyway, compliment for your .Net suite (ultimate) which I gona buy. I work as a professional on data capturing projects and I am impressed about the functionality and the fast processing of your suite.
The reason why I need to create my own program is because Abbyy's recognition Server does have massive problems with their 2d barcode engine. maybe you can help them out of their mess.... :)

Kind regards
Beat

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Loïc
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Posts: 5564
Joined: Tue Oct 17, 2006 10:48 pm
Location: France
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Re: DataMatrix recognition sometimes fails

Post by Loïc » Fri Sep 16, 2011 1:18 pm

Hi Beat,

Thank you for your message.

You can send us the document that fail to be recognized via http://support.gdpicture.com

Just clarify that documents are confidential & please attach the code snippet.

Basically, your problem is known from our team. We put frequent research efforts to be able to fast decode data in any kind of resolution. A workaround consists to render each page in 72, 100 & 200 and try 3 processes stopping when the first which is successful. Of course this is a not really sexy workaround that takes at least 2x more time. But that works, and sometime this is faster (and more accurate) than many engines of our competitors...
Anyway, 72 DPI seems to low to get correct accuracy. I suggest something in the range [150-200].

Kind regards,

Loïc

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