menuimage

Description

Usage

Options

Dependencies

License

Changelog

Download

Donation

My_Other_Sites

My_Programs

Comments

pdf-compress v1.3 [28 Apr 2022] - by Dominic

Description

GNU/Linux program to compress an overly large pdf file to smaller monochrome. Typical use case is a file generated by scanning with unnecessarily high resolution and/or color. The objective is a file that although not of the same quality as the original, is still legible and much smaller (90%+ size reductions are common). This is achieved by conversion to 1-bit pixel mapping, so is typically most effective for dark text on a white background.

If destination path/file is unspecified pdf-compress.sh will create a file in the same location as source, with -1 suffixed to the filename (before .pdf extension). If destination is a directory then the created file will have the same name as the source file. pdf-compress.sh will also set the destination file to have the same ownership, group and modtime as the original file (but ownership can only be changed if running as superuser).

If a target maximum percentage size is set (-r option) and the initial compression attempt does not achieve at least this reduction, pdf-compress.sh will retry, varying the GhostScript resize parameter (initial value 300) until (hopefully) it can achieve something close to the specified value (but absolute accuracy of resizing is not to be expected).

If qpdf is present it is used (after GhostScript) to make a further c.10% filesize saving with no effect on quality; with -r this 10% is included in the specified target so the resulting file will have slightly better quality, not smaller size, than would have been achieved without qpdf. Downside: compressing with qpdf is relatively slow.

If exiftool is present it is used to update the 'Producer' metadata in the destination file to show that it was processed by pdf-compress.sh, and when - see also options -m and -n.

[Deprecated: specify additional options to be passed to the ImageMagick convert operation within pdf-compress.sh by using -p; for instance, to hide a watermark try -p '-white-threshold 60%'.]

Usage

./pdf-compress.sh [options] source_path/filename [destination_path[/filename]]

Options

-f - overwite (replace original file)
-h - show this help and exit
-l - show changelog and exit
-m - test (without making any changes) if file has previous been processed by pdf-compress.sh (like -n below); exit code 1 if so or 0 if not (can be combined with -q for silent checking) - requires exiftool
-n - skip making any changes if file has previously been processed by pdf-compress.sh (i.e. if the 'Producer' metadata contains 'pdf-compress.sh') - requires exiftool
-p 'param1 param2' - additional parameters for ImageMagick 'convert' command [deprecated]
-q - be quieter (1 line output if successful)
-r num - target maximum percentage size vs original (so, 40 means at least 60% file size reduction)
-t path - directory to use for temporary files, which can be large (default: /tmp)
-y - overwrite destination file if it already exists

Dependencies

bash(4+) convert(ImageMagick) exiftool* gs(GhostScript) qpdf*
* not required but used for additional functionality if available

License

Copyright © 2022 Dominic Raferd. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0. Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Changelog

1.3 [28 Apr 2022] - add -m (check if already processed without taking any other action)
1.2 [11 Apr 2022] - add -f (force overwrite) option
1.1 [08 Apr 2022] - improved output using GS 'Hybrid2' setting by Adam Lesser - kudos (see https://bugs.ghostscript.com/show_bug.cgi?id=694762)
1.0 [31 Mar 2022] - minor changes
0.9 [03 Mar 2022] - add -n option, set 'Producer' metadata (no effect if exiftool unavailable), remove -v option, make -q option non-silent
0.8 [13 Feb 2022] - modify -r option to be an 'aim for' percentage size reduction (by looping), remove -n (negate) option as irrelevant, add use of qpdf (if present) for additional c.10% size saving
0.7 [10 Feb 2022] - improved (and simplified) by using gs pngmonod device, align owner/group, permissions and modtime of created file with those of the original
0.6 [05 Aug 2020] - added more gs settings (kudos: Enno Nagel)
0.5 [16 Nov 2017] - negate by default (-n to non-negate), default resize 200 not 100, add -p option
0.4 [23 Apr 2017] - add -n (negative) option
0.3 [16 Oct 2016] - fix for temporary file deletion, make temporary filenames unique
0.2 [21 Sep 2016] - lots of tweaks
0.1 [20 Sep 2016] - initial version

Download pdf-compress.sh

Donation

I have provided this software free gratis and for nothing. If you would like to thank me with a contribution, please let me know and I will send you a link. Thank you!

My Other Sites

My Programs

Here is a selection of some (other) programs I have written, most of which run from the command line (CLI), are freely available and can be obtained by clicking on the links. Dependencies are shown and while in most cases written for a conventional Linux server, they should run on a Raspberry Pi, and many can run under Windows using Windows Subsystem for Linux (WSL) or Cygwin. Email me if you have problems or questions, or if you think I could help with a programming requirement.

Backup Utilities

Debian/Ubuntu kernel and LVM Utilities

Dellmont - VoIP and Mobile Phone Account Utilities

Miscellaneous Programs

Comments

If you have a comment or question, please email me, thank you.

Spiv 14 Oct 2016, 16:02
Hi Dominic,
thank you for this nice program!

How do I actually install and then use it on Ubuntu 16.04 (I am a bit of a novice....)?

Keep smiling
Spiv
Kaan 25 May 2019, 12:01
Hello, I downloaded pdf-compress.sh and made it executable from permission of file. I correctly entered
./pdf-compress.sh myfile.pdf (which is at same directory, no mistake in path of file, I'm sure)
in terminal but it only writes
pdf-compress: (cursor waits without doing anything, I can type characters from keyboard but don't know why script does not compress my pdf file as you define in usage section)
and waits without doing process. What is problem?
Nadya 12 Aug 2019, 07:23
Hi! I have similar error with Kaan, how we can fix it?
Moish 12 Aug 2019, 08:32
Is it free?
Dominic Raferd 12 Aug 2019, 08:35
@Moish - yes!