基于PyPDF4 写一个去除未知PDF水印的程序

好的，我可以为您提供一个基于PyPDF4的程序来去除未知PDF水印。以下是代码：

import PyPDF4

def remove_watermark(input_file, output_file):
    # Open the PDF file
    with open(input_file, 'rb') as file:
        pdf_reader = PyPDF4.PdfFileReader(file)

        # Create a new PDF writer object
        pdf_writer = PyPDF4.PdfFileWriter()

        # Loop through each page of the PDF
        for page_num in range(pdf_reader.getNumPages()):
            # Get the current page
            page = pdf_reader.getPage(page_num)

            # Remove the watermark by overwriting it with a blank rectangle
            if '/Annots' in page:
                page_dict = page.getObject()
                annots = page_dict['/Annots'].getObject()
                for annot in annots:
                    if '/AP' in annot:
                        annot_dict = annot.getObject()
                        if '/N' in annot_dict['/AP']:
                            stream = annot_dict['/AP']['/N'].getObject()
                            if '/BBox' in stream:
                                stream.remove('/BBox')
                                stream.remove('/Matrix')
                                stream.stream = b'q 1 0 0 1 0 0 cm /Im1 Do Q'
                                annot.update()

            # Add the updated page to the new PDF writer object
            pdf_writer.addPage(page)

        # Write the updated PDF to a file
        with open(output_file, 'wb') as output:
            pdf_writer.write(output)

# Test the program
input_file = 'input.pdf'
output_file = 'output.pdf'
remove_watermark(input_file, output_file)

使用该程序时，将输入文件和输出文件的文件路径传递给`remove_watermark`函数即可。该程序会打开输入文件，遍历每一页，检查是否存在水印，如果存在，则将其用空白矩形覆盖。最后，将更新后的页面添加到新的PDF文件中并保存为输出文件。

请注意，此程序仅适用于某些类型的PDF水印。对于其他类型的水印，可能需要不同的处理方法。