apply_redactions moves some unredacted text

[indigoviolet]

Description of the bug

Before:

After:

source.pdf
result_annotated.pdf

---

Notes:

• a similar issue was previously reported in apply_redactions() moving text #2957
• this is being reported on behalf of an Enterprise support customer (I can email details separately if needed).
• We have noticed that some issues like this are resolved when using Preview.app to (re-) print the PDF with "scale to fit" turned on.

How to reproduce the bug

import fitz

source_doc = fitz.open('source.pdf')
dst_doc = fitz.open()
dst_doc.insert_pdf(source_doc, 0, 0)

redaction_coords = [(507.3806485, 35.06467372292002, 552.9736259804001, 24.838430185399943),
                    (212.5271666879999, 137.43544772292012, 258.12014416840003, 127.20920418540004),
                    (212.527166688, 129.4908031440001, 258.1201441684001, 139.2412260440001)]

page = dst_doc.load_page(0)

for coords in redaction_coords:
        redaction = page.add_redact_annot(
            coords,
            text="  ",
            fill=(0.5, 0.5, 0.5),  # grey
        )
        redaction.update()

fitz.utils.apply_redactions(page)

dst_doc.save("result.pdf")
dst_doc.close()

PyMuPDF version

1.23.26

Operating system

MacOS

Python version

3.11

[JorjMcKie]

Sorry - I was wrong: got confused by the first two coords rectangles: they are empty and thus invalid.
Re-opened this issue.
It is an error in the base library, and I will submit an issue there.

The error has nothing to do with redactions. The page's /Contents stream is destroyed even when "cleaning" the PDF (part of the internal redaction process).

[JorjMcKie]

In this case, the PDF resulting from a PDF-to-PDF conversion will not cause a problem. So you can use this approach is you need an immediate circumvention:

import fitz

source_doc = fitz.open("source.pdf")
pdfdata = source_doc.convert_to_pdf()  # make a PDF/PDF conversion
# this will issue some error messages: obviously, some fonts contain errors.
source_doc = fitz.open("pdf", pdfdata)  # re-open source after conversion
dst_doc = fitz.open()
dst_doc.insert_pdf(source_doc, 0, 0)

redaction_coords = [
    (507.3806485, 35.06467372292002, 552.9736259804001, 24.838430185399943),
    (212.5271666879999, 137.43544772292012, 258.12014416840003, 127.20920418540004),
    (212.527166688, 129.4908031440001, 258.1201441684001, 139.2412260440001),
]

page = dst_doc.load_page(0)

for coords in redaction_coords:
    if fitz.Rect(coords).is_empty:
        print(f"normalizing empty rect {coords=}")
        coords = tuple(fitz.Rect(coords).normalize())
    redaction = page.add_redact_annot(
        coords,
        text="  ",
        fill=(0.5, 0.5, 0.5),  # grey
    )
    page.draw_rect(coords, color=(1, 0, 0))

page._apply_redactions(0, 0)

dst_doc.save("result.pdf")
dst_doc.close()

[JorjMcKie]

Issue number in MuPDF's issue system: https://bugs.ghostscript.com/show_bug.cgi?id=707673.

[manjuadditive]

In this case, the PDF resulting from a PDF-to-PDF conversion will not cause a problem. So you can use this approach is you need an immediate circumvention:

import fitz

source_doc = fitz.open("source.pdf")
pdfdata = source_doc.convert_to_pdf()  # make a PDF/PDF conversion
# this will issue some error messages: obviously, some fonts contain errors.
source_doc = fitz.open("pdf", pdfdata)  # re-open source after conversion
dst_doc = fitz.open()
dst_doc.insert_pdf(source_doc, 0, 0)

redaction_coords = [
    (507.3806485, 35.06467372292002, 552.9736259804001, 24.838430185399943),
    (212.5271666879999, 137.43544772292012, 258.12014416840003, 127.20920418540004),
    (212.527166688, 129.4908031440001, 258.1201441684001, 139.2412260440001),
]

page = dst_doc.load_page(0)

for coords in redaction_coords:
    if fitz.Rect(coords).is_empty:
        print(f"normalizing empty rect {coords=}")
        coords = tuple(fitz.Rect(coords).normalize())
    redaction = page.add_redact_annot(
        coords,
        text="  ",
        fill=(0.5, 0.5, 0.5),  # grey
    )
    page.draw_rect(coords, color=(1, 0, 0))

page._apply_redactions(0, 0)

dst_doc.save("result.pdf")
dst_doc.close()

@JorjMcKie
We are trying this solution, but we are getting too many cannot create ToUnicode mapping warnings which are making redactions harder. In such cases convert_to_pdf probably (can you confirm?) converts the underlying text to images. When we redact the area with PDF_REDACT_IMAGE_REMOVE option, the images doesn't seem to get removed.

UPDATE: I don't think convert_to_pdf is creating images when cannot create ToUnicode mapping is encountered. But I am lost on what the replacement object is. And it is certainly not getting redacted although it overlaps the redaction bounds.

[JorjMcKie]

Document.convert_to_pdf() does not convert page content to images. However, as the documentation explains, only a subset of fonts is eligible for such a conversion.
And of course: internally all text and other content is rewritten to the new PDF, therefore any errors in that area are detected and complained about.

[manjuadditive]

Document.convert_to_pdf() does not convert page content to images. However, as the documentation explains, only a subset of fonts is eligible for such a conversion. And of course: internally all text and other content is rewritten to the new PDF, therefore any errors in that area are detected and complained about.

What happens if the conversion fails?

[JorjMcKie]

An exception is raised. There also is the risk of incomplete / distorted output.
As I wrote: a possible circumvention for the time being.
Not meant as a permanent solution.

[indigoviolet]

@JorjMcKie do you need our customer details to fill in on the MuPDF issue so it gets the corresponding priority?

[JorjMcKie]

@JorjMcKie do you need our customer details to fill in on the MuPDF issue so it gets the corresponding priority?

Yes, please provide it if available.

[JorjMcKie]

Receive the customer id - thank you!

[julian-smith-artifex-com]

Fixed in 1.24.1.