Remove text from a PDF

[samuelbradshaw]

Hi! Is there an efficient way to remove/delete all text from a PDF with PyMuPDF?
Also, is there a way to remove all text that uses a specific font from a PDF?

[JorjMcKie]

The easiest way to remove all text is using "redaction annotations" (from all or selected pages):

doc = pymupdf.open("input.pdf")
page = doc[0]  # 0 or any 0-based page number
page.add_redact_annot(page.rect)  # redaction annotation covering the full page
page.apply_redactions(images=pymupdf.PDF_REDACT_IMAGE_NONE,  # keep the images
    graphics=pymupdf.PDF_REDACT_LINE_ART_NONE,  # keep vector graphics
    )

Specific text erasures work the same way, except you have to determine the desired boundary box to use instead of page.rect.

# extract text and full meta data exclusively (no images)
for block in page.get_text("dict", flags=pymupdf.TEXTFLAGS_TEXT)["blocks"]:
    for line in block["lines"]:
        for span in line["spans"]:
            if "unwanted font name" in span["font"]:
                page.add_redact_annot(span["bbox"])  # cover text span with redact annot
page.apply_redactions(images=pymupdf.PDF_REDACT_IMAGE_NONE,  # keep the images
    graphics=pymupdf.PDF_REDACT_LINE_ART_NONE,  # keep vector graphics
    )

Important:

• Save the PDF with garbage collection and compression: doc.ez_save(..).
• Every text will be deleted which touches (intersects) any redaction annotation. This may be more than desired if e.g. text is written overlapping each other, or lines have a distances narrower than the font-specific line height. When this occurs, some special precaution defining the redact rectangles is required.
• Obviously, the second alternative can be adapted to other selection criteria like text color or font size etc.

[zergb]

Thanks a lot for the solution! The method is realy elegent!

Still have one more question about the solution. The texts inside widgets cannot removed. It looks like widgets are always above any element in page, such as redaction. So the texts are not "covered" by redaction. Is there any way to handle them with the same method?

[JorjMcKie]

1. You are right to say that annotations and widgets are "above" the page. I like to use the metaphor "like dust on a glass frame of a painting".
2. You have the option to remove annotations or widgets via respective page.delete_annot()/page.delete_widget().
3. You can also "bake in" both types document-wide via method bake(). This converts annots and / or widgets to permanent page content and thus makes them reachable for redactions.

[zergb]

Understood. The doc.bake() function works perfect as expected! After that the texts in input widgets can be hidden by redaction.

[WorstCodeWay]

How about deleting text without touching any watermark? Does this way work?

[JorjMcKie]

Depending on how the watermark is implemented, there is a fat chance that it will remain untouched. Emptying an area as mentioned above can be made selective to leave images and graphics untouched. PDF-compliant watermarks will be retained anyway.
If however your watermarks are normal text, then they will be erased in the red area.
Depends on an experiment.