如何使用PDF框去除内容上的水印？不在内容下

Question

我用PDF版本2.0.27写了一个去除水印的程序，但是这个方法只能去除内容下面的水印，不能去除上面的水印。是否可以从内容中删除水印并将删除的水印另存为新的 PDF 文件？非常感谢！

我想找到正确的学习代码

Answer 1

我尝试了以下代码，该代码是根据 pymupdf github 讨论查找并删除 PDF 文件中的水印中的代码进行了一些修改。它在当前的 pymupdf 版本上工作正常。

pip install PyMuPDF

import pymupdf

def process_page(page : pymupdf.Page):
    """Process one page."""
    # doc = page.parent  # the page's owning document
    # page.clean_contents()  # clean page painting syntax
    xref = page.get_contents()[0]  # get xref of resulting /Contents
    changed = 0  # this will be returned
    # read sanitized contents, splitted by line breaks
    cont_lines = page.read_contents().splitlines()
    print(len(cont_lines))
    # print(cont_lines)
    for i in range(len(cont_lines)):  # iterate over the lines
        line = cont_lines[i]
        # print(line)
        if not (line.startswith(b"/Artifact") and b"/Watermark" in line):
            continue  # this was not for us
        # line number i starts the definition, j ends it:
        print(line)
        j = cont_lines.index(b"EMC", i)
        for k in range(i, j):
            # look for image / xobject invocations in this line range
            do_line = cont_lines[k]
            if do_line.endswith(b"Do"):  # this invokes an image / xobject
                cont_lines[k] = b""  # remove / empty this line
                changed += 1
    if changed > 0:  # if we did anything, write back modified /Contents
        doc.update_stream(xref, b"\n".join(cont_lines))
    return changed

fpath = 'your_pdf_file_path/file_name.pdf'
doc = pymupdf.open(fpath)
changed = 0  # indicates successful removals
for page in doc:
    changed += process_page(page)  # increase number of changes
if changed > 0:
    x = "s" if doc.page_count > 1 else ""
    print(f"{changed} watermarks have been removed on {doc.page_count} page{x}.")
    doc.ez_save(doc.name.replace(".pdf", "-nowm.pdf"))
else:
    print("Nothing to change")