PDF Box getXObjectNames() does not recognize bar code on my PDF, however it does recognize it on a PDF file I got off the internet

I am trying to fetch and read bar codes from my PDF using getXObjectNames() of PdResources.

• My code is very similar to this link: https://issues.apache.org/jira/browse/PDFBOX-2124

If you see the above JIRA item, you will see a PDF file attached to it.
When I run the code on that PDF file I get the desired output (i.e. the bar code type is printed.)

However when I run it on my PDF, it does not recognize the bar code in it. (I have checked that the bar code is in fact an image and not text.)

Also it may sound weird, but it did work on my PDF once and I haven't made any changes since then, but it definitely does not work now. (I cannot share the PDF for some reason.)

Has anyone faced a similar issue?

Also this is my first question on Stack Overflow. Please tell me if I am wrong anywhere.

Here is a link to that pdf:
https://drive.google.com/file/d/1PzVApIePg4U9XL399BpAd2oeY6Q2tLEB/view?usp=drivesdk

In General

As you don't show your code but only describe it as very similar to that in PDFBOX-2124, and as you say you cannot share the PDF for some reason, I only have that code to analyze. Thus, I cannot tell what really is the issue but merely enumerate some possible problems

First of all, that code only inspects the immediate resources of the given page for bitmap images:

PDResources pdResources = pdPage.getResources();

Map<String, PDXObject> xobjects = (Map<String, PDXObject>) pdResources.getXObjects();
if (xobjects != null)
{
    for (String key : xobjects.keySet())
    {
        PDXObject xobject = xobjects.get(key);
        if (xobject instanceof PDImageXObject)
        {
            PDImageXObject imageObject = (PDImageXObject) xobject;
            String suffix = imageObject.getSuffix();
            if (suffix != null)
            {
                BufferedImage image = imageObject.getImage();
    			extractBarcodeArrayByAreas(image, this.maximumBlankPixelDelimiterCount);
            }
        }
    }
}	

(PDFBOX-2124 PdPageBarcodeScanner method scsan)

Bitmap images can also be stored elsewhere, e.g.

• in the separate resources of form xobjects, patterns, or Type 3 fonts used on the page; to find them one has to inspect other page resources, too, even recursively as the image might be a resource of a pattern used in a form xobject used on the page;
• in the separate resources of annotations of the page; thus, one has to recurse into annotation resources, too;
• inlined in some content stream; thus, one also has to search the content streams of the page itself, of page resources (recursively), and page annotations and their resources (recursively).

Furthermore, the bitmap might be given in some format (in particular with some colorspace) which PDFBox does not know how to export as BufferedImage.

Also the bar code may be constructed using some mask applied to a purely black bitmap in which case your code probably only tries to scan that purely black image.

Furthermore, you say

> I have checked that the bar code is in fact an image and not text.

If you only checked that the bar code is not text, it may not only be a bitmap image but it can also be drawn by vector graphics instructions. Thus, you also have to check all content streams for vector graphics instructions drawing a bar code.

Also there may be combinations, e.g. a soft mask of vector graphics may be active when drawing a purely black inlined bitmap image etc.

And I'm sure I've missed a number of options here.

As next step you may want to analyze the PDF you cannot share to find out how exactly that barcode is drawn.

Alternatively, you render the page as bitmap image and search that large bitmap for bar codes using zxing.

Sample PDF.pdf

You provided a link to a sample PDF. So I tried to extract the bar code using code very similar to that from PDFBOX-2124. Apparently the code there was for some PDFBox 2.0.0-SNAPSHOT, so it had to be corrected a bit. In particular the method getXObjectNames() you mention in the question title finally is used:

PDResources pdResources = pdPage.getResources();
int index = 0;

for (COSName name : pdResources.getXObjectNames()) {
    PDXObject xobject = pdResources.getXObject(name);
    if (xobject instanceof PDImageXObject)
    {
        PDImageXObject imageObject = (PDImageXObject) xobject;
        String suffix = imageObject.getSuffix();
        if (suffix != null)
        {
            BufferedImage image = imageObject.getImage();

            File file = new File(RESULT_FOLDER, String.format("Sample PDF-1-%s.%s", index, imageObject.getSuffix()));
            ImageIO.write(image, imageObject.getSuffix(), file);
            index++;
            System.out.println(file);
        }
    }
}

(ExtractImages test testExtractSamplePDFJayshreeAtak)

The output: One bitmap image is exported as "Sample PDF-1-0.tiff" which looks like this:

Thus, I cannot reproduce your issue

> PDF Box getXObjectNames() does not recognize bar code on my PDF, however it does recognize it on a PDF file I got off the internet

Obviously getXObjectNames() does return the name of the bitmap image xobject resource and PDFBox exports it just fine.

Please check with your code whether as claimed the image is not extracted or whether some later step simply cannot deal with it.

If in your case indeed the image is not extracted,

• update your PDFBox version (I used the current development head but the newest released version should return the same),
• update your Java,
• check whether you have extra JAI jars that might cause trouble.

If in your case the image is extracted but not analyzed as expected by later code,

• debug more thoroughly to find out where the analysis fails,

• create a new question here focusing on the QR code image analysis,

• and provide enough code and the tiff file to allow people to actually reproduce the issue.