Bookmarking a PDF also shrinks its file size and compresses images

[madamadami]

I like your script and used it quite a lot recently. Unfortunately, the PDFs get compressed pretty much and so images lose a lot of quality. How can I avoid recompression?

[smfukaya]

@madamadami, perhaps you could add the Ghostscript settings (highlighted in bold) posted Kurt Pfeifle is his answer to Use Ghostscript, but tell it to not reprocess images?.

So the complete Ghostscript commandline that could make you happy should read:

gs
-o book.pdf
-sDEVICE=pdfwrite
-dColorConversionStrategy=/LeaveColorUnchanged
-dDownsampleMonoImages=false
-dDownsampleGrayImages=false
-dDownsampleColorImages=false
-dAutoFilterColorImages=false
-dAutoFilterGrayImages=false
-dColorImageFilter=/FlateEncode
-dGrayImageFilter=/FlateEncode
title.pdf
content.pdf

Find where your pdf-bookmark was installed with the following command:
pip show pdf-bookmark

Name: pdf-bookmark
Version: 1.1.0
Summary: PDF Bookmark Import and Export
Home-page: https://github.com/xianghuzhao/pdf-bookmark
Author: Xianghu Zhao
Author-email: xianghuzhao@gmail.com
License: MIT
Location: c:\LOCATION\python\python310\lib\site-packages
Requires:
Required-by:

Edit the "c:\LOCATION\python\python310\lib\site-packages\pdf-bookmark.py" (change the path accordingly) file, find the call command to ghostscript executable, add the above settings to the arguments array and save the file.

    call(['gs', '-dBATCH', '-dNOPAUSE', '-sDEVICE=pdfwrite',
          '-dColorConversionStrategy=/LeaveColorUnchanged', '-dDownsampleMonoImages=false', '-dDownsampleGrayImages=false', '-dDownsampleColorImages=false',
          '-dAutoFilterColorImages=false', '-dAutoFilterGrayImages=false', '-dColorImageFilter=/FlateEncode', '-dGrayImageFilter=/FlateEncode',
          '-sOutputFile={}'.format(output_pdf),
          pdfmark_noop,
          pdf,
          pdfmark_restore,
          pdfmark_file,
          pdfmark_pagemode])

Run the pdf-bookmark and check if the image quality suits your need.