How to know if PDF can have watermark (under text) or just a stamp (on top)? #1197
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I have different PDF files: some are digitally generated and some are scans / images. I have to put watermark on them and preferable under the text. I used Is there a better way to determine if watermark can be behind text? |
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Replies: 1 comment 4 replies
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The issue you encounter is that the watermark goes behind an image. You could check if the page contains any image. Something like this: def contains_image(page: PageObject) -> bool:
page_resources = page["/Resources"]
x_object = page_resources.get("/XObject", {})
for obj in x_object:
obj_ = x_object[obj]
if obj_["/Subtype"] == "/Image":
return True
return FalseYou could enhance this with the image dimensions. Or you could look at metadata (the generator). If you see Epson / Canon or similar in there, there is a good chance that it's a scanner. |
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Oh, that should work, thanks! |
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But! I tested this on the pdf with text, where underlying watermark works and it also contains images (logo), but watermark is displayed properly behind the text. |
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Yes, it's not a bullet-proof method. You could use pymupdf (Fitz) to render the complete page before and after as an image. If the image changed, you know that at least a part of the watermark is visible |
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You could also look at the size / position of the image |
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The issue you encounter is that the watermark goes behind an image. You could check if the page contains any image.
Something like this:
You could enhance this with the image dimensions. Or you could look at metadata (the generator). If you see Epson / Canon or similar in there, there is a good chance that it's a scanner.