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At all dpi's I get different results

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
15/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
csharp
Domain
computer-vision

Research direction

Start with the reporter's snippet: RenderPageToImage(CurrentPage, Dpi) produces the bitmap, which is passed to BarcodeReader.DecodeMultiple with AutoRotate, TryInverted, TryHarder and a long PossibleFormats list. Reproduce by rendering one PDF page at 72, 96, 150, 200, 300 and 600 dpi and comparing decode results, then check whether the library's binarizer or the format list causes the variation. The issue is open-ended, so done means either a documented approach that finds the barcode across dpi values or a clear explanation of why it cannot be done.

Written by the indexing model from the issue text.

Description

I tried to get the barcode from this page
Screenshot 2022-12-12 143259
I tried to get it with this code:

            Image currentPageImage = RenderPageToImage(CurrentPage, Dpi);

            BarcodeReader barcodeReader = new BarcodeReader()
            {
                AutoRotate = true,
                Options = new ZXing.Common.DecodingOptions()
                {
                    TryInverted = true,
                    PureBarcode = false,
                    TryHarder = true,
                    PossibleFormats = new List<BarcodeFormat>() { BarcodeFormat.AZTEC, BarcodeFormat.CODABAR, BarcodeFormat.CODE_39, BarcodeFormat.CODE_93, BarcodeFormat.CODE_128, BarcodeFormat.DATA_MATRIX, BarcodeFormat.EAN_8, BarcodeFormat.EAN_13, BarcodeFormat.ITF, BarcodeFormat.MAXICODE, BarcodeFormat.PDF_417, BarcodeFormat.QR_CODE, BarcodeFormat.RSS_14, BarcodeFormat.RSS_EXPANDED, BarcodeFormat.UPC_A, BarcodeFormat.UPC_E, BarcodeFormat.All_1D, BarcodeFormat.UPC_EAN_EXTENSION, BarcodeFormat.MSI, BarcodeFormat.PLESSEY, BarcodeFormat.IMB, BarcodeFormat.PHARMA_CODE }
                }
            };
            Result[] results = barcodeReader.DecodeMultiple((Bitmap)currentPageImage);
            Result = string.Empty;
            if (results != null)
            {
                foreach (Result result in results)
                {
                    Result += result.Text + Environment.NewLine;
                }
            }

If I now use 72 dpi (standard PDF dpi) I get no results.
If I use 96 dpi (standard WPF dpi) I get = [95001, 6, 3]
150 dpi = [6, 9, 11117131, 7, 3, 8000, 4]
200 dpi = [14, 00800000000, 3, 6, 000, 00000000, 7, 35, 9, 4]
300 dpi = [6, 4, 3]
600 dpi = [6, 3, 8, 5, 7, 4]

So my question would be: "How can I get this barcode if I do NOT know in which codec it was printed?"
We get different PDF documents and have to scan them for all barcodes.
How could I achieve that or is it even possible with this library?

Dominant language
C#
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Merged PRs (30d)
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