How can I reduce the file size of a scanned PDF file?

Question

I have a 72.9 MB PDF file that I need to shrink to 500 KB or below.

The file was a JPEG image that I had scanned and then converted to PDF.

Answer 1

Use the following Ghostscript command:

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook \
-dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

Summary of -dPDFSETTINGS:

• -dPDFSETTINGS=/screen lower quality, smaller size. (72 dpi)
• -dPDFSETTINGS=/ebook for better quality, but slightly larger pdfs. (150 dpi)
• -dPDFSETTINGS=/prepress output similar to Acrobat Distiller "Prepress Optimized" setting (300 dpi)
• -dPDFSETTINGS=/printer selects output similar to the Acrobat Distiller "Print Optimized" setting (300 dpi)
• -dPDFSETTINGS=/default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file

Reference:

Controls and features specific to PostScript and PDF input

-dPDFSETTINGS=configuration

Presets the "distiller parameters" to one of four predefined settings:

• /screen selects low-resolution output similar to the Acrobat Distiller (up to version X) "Screen Optimized" setting.
• /ebook selects medium-resolution output similar to the Acrobat Distiller (up to version X) "eBook" setting.
• /printer selects output similar to the Acrobat Distiller "Print Optimized" (up to version X) setting.
• /prepress selects output similar to Acrobat Distiller "Prepress Optimized" (up to version X) setting.
• /default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.

The exact settings for each of these, including their DPI values, are shown in the dozens of options in this table.

Answer 2

My favorite way to do this is to convert the PDF to PostScript and back. It does not always work, though, but when it works the results are nice:

ps2pdf input.pdf output.pdf

This also directly works on PDFs, as suggested in the comments.

Some users also report more success when using the ebook settings as follows:

ps2pdf -dPDFSETTINGS=/ebook input.pdf output.pdf

Answer 3

aking1012 is right. With more information regarding possible embedded images, hyperlinks etc.. it would be much more easier to answer this question!

Here are a couple of script and command-line solutions. Use as you see fit.

• reduce-pdf-file-size-linux
• shrinkpdf
• compress-a-pdf-with-pdftk
• pdfcompress

Answer 4

If you have a pdf with scanned images, you can use convert (ImageMagick) to create a pdf with jpeg compression (You can use this method on any pdf, but you'll loose all text informations).

For example:

convert -density 200x200 -quality 60 -compress jpeg input.pdf output.pdf

Adjust the parameters to your needs

• -density: the pixel density in dpi (e.g. 100x100). Higher pixel densities increase quality and size
• -quality: the compression ratio. For jpg it is between 1 to 100 with 100 the best quality, but lowest compression
• -compress: the compression algorithm. jpeg compression might not be the best choice due to compression artifacts. You have the choice between BZip, Fax, Group4, JPEG, JPEG2000, Lossless, LZW, RLE or Zip as alternate compression methods (some only allow b/w images).

I was able to achieve great compression ratios for scanned/photographed documents (depending on the settings). Depending on the document source, you might want to reduce the color depth (-depth argument).

Answer 5

I needed to downsize a PDF that contained full color scans of a document. Each of my pages was a full color image as far as the file was concerned. They were images of pages containing text and images, but they were created by scanning to an image.

I used a combination of the below ghostscript command and one from another thread.

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dDownsampleColorImages=true \
-dColorImageResolution=150 -dNOPAUSE  -dBATCH -sOutputFile=output.pdf input.pdf

This reduced the image resolution to 150dpi, cutting my file size in half. Looking at the document, there was almost no noticeable loss of image quality. The text is still perfectly readable on my 2012 Nexus7.

Answer 6

Here is a script for rewriting scanned pdfs:

#!/bin/sh

gs  -q -dNOPAUSE -dBATCH -dSAFER \
    -sDEVICE=pdfwrite \
    -dCompatibilityLevel=1.3 \
    -dPDFSETTINGS=/screen \
    -dEmbedAllFonts=true \
    -dSubsetFonts=true \
    -dColorImageDownsampleType=/Bicubic \
    -dColorImageResolution=72 \
    -dGrayImageDownsampleType=/Bicubic \
    -dGrayImageResolution=72 \
    -dMonoImageDownsampleType=/Bicubic \
    -dMonoImageResolution=72 \
    -sOutputFile=out.pdf \
     $1

You could customise it a bit to make it more reusable but if you only have one pdf, you could just replace $1 with your pdf filename and bung it in a terminal.

Answer 7

1. I use LibreOffice Draw to open the pdf.
2. I then "export as pdf"
3. And set "jpeg compression quality" to 50% and "image resolution" to 150 dpi

This will have a good result.

Answer 8

I usually use ps2pdf to do this (easier syntax), something like this:

ps2pdf -dPDFSETTINGS=/ebook BiggerPdf SmallerPDF

I use the following python script to reduce the size of all the pdf files in a dir in a production server (8.04). So it should work.

#!/usr/bin/python

import os

for fich in os.listdir('.'):
        if fich[-3:]=="pdf":
                os.system("ps2pdf -dPDFSETTINGS=/ebook %s reduc/%s" % (fich,fich))

Answer 9

Best for me was

convert -compress Zip -density 150x150 input.pdf output.pdf

Other ways:

#### gs
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf $INPUTFILE

### pdf2ps && ps2pdf
pdf2ps input.pdf output.ps && ps2pdf output.ps output.pdf

### Webservice
http://compress.smallpdf.com/de

regards

Answer 10

For my other, pdfsizeopt-based answer, see here.

Referencing this answer and this answer, and after trying a bunch of the answers here, and doing a bunch of research and experimenting, I've come up with the following. Note that I've removed the -dCompatibilityLevel=1.4 part of the command used in some other answers here (including the most-upvoted answer) because this table indicates that 1.5 or 1.7 are automatically used for this setting today (27 Dec. 2020), and there's no need to override those values.

Use Ghostscript (gs) to compress input.pdf into output.pdf

3 Main levels of compression:
Note: you may also add -dQUIET to suppress all output to stdout. See: https://ghostscript.readthedocs.io/en/latest/Use.html.

1. Low compression: 300 dpi (large file size)

   gs -sDEVICE=pdfwrite -dPDFSETTINGS=/printer -dNOPAUSE -dBATCH \
   -sOutputFile=output.pdf input.pdf
   

2. [BEST in my testing] Medium compression (recommended): 150 dpi (medium file size)

   gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook   -dNOPAUSE -dBATCH \
   -sOutputFile=output.pdf input.pdf
   

3. High compression: 72 dpi (small file size--may produce grainy or unreadable results in some cases, so try it and give it a shot)

   gs -sDEVICE=pdfwrite -dPDFSETTINGS=/screen  -dNOPAUSE -dBATCH \
   -sOutputFile=output.pdf input.pdf
   

You can also add time in front of the command to see how long it takes (this works with any Linux command). Sample output:

$ time gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -sOutputFile=out.pdf in.pdf
GPL Ghostscript 9.50 (2019-10-15)
Copyright (C) 2019 Artifex Software, Inc.  All rights reserved.
This software is supplied under the GNU AGPLv3 and comes with NO WARRANTY:
see the file COPYING for details.
Processing pages 1 through 15.
Page 1
Loading NimbusSans-Regular font from /usr/share/ghostscript/9.50/Resource/Font/NimbusSans-Regular... 5205104 3852122 2872760 1487237 3 done.
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15
real    0m1.326s
user    0m1.142s
sys     0m0.048s

If you add -dQUIET to the command, none of the Ghostscript output is shown, and you get this (when using time in front):

$ time gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -dQUIET -sOutputFile=out.pdf in.pdf
real    0m1.018s
user    0m0.976s
sys     0m0.040s

You can also use ps2pdf, which is a wrapper around gs, and produces very similar, but not exactly identical, results. I prefer to just use gs directly, as shown above, however.

1. Low compression: 300 dpi (large file size)

   ps2pdf -dPDFSETTINGS=/printer input.pdf output.pdf
   

2. Medium compression (recommended): 150 dpi (medium file size)

   ps2pdf -dPDFSETTINGS=/ebook   input.pdf output.pdf
   

3. High compression: 72 dpi (small file size--may produce grainy or unreadable results in some cases, so try it and give it a shot)

   ps2pdf -dPDFSETTINGS=/screen  input.pdf output.pdf
   

PDF Compression Tests

Testing the gs commands above on output from my pdf2searchablepdf script here, I see the following:

1. Low compression: has no significant effect since my script already produces 300 dpi output PDFs. So, a 3.8 MB 3 pg input PDF results in an output PDF of ~3.8MB.
2. [BEST] Medium compression: compresses the file nicely! A 3.8 MB 3 pg input PDF results in an output PDF of ~0.95MB.
3. High compression: may be too much. A 3.8 MB 3 pg input PDF results in an output PDF of ~0.37MB, BUT in my particular test is completely unreadable, since the input PDF was already of somewhat poor resolution to begin with. If you begin with a high quality/high resolution input PDF, you may have much better, readable results.

Ghostscript (gs) Documentation:

For all -d ("define") PDFSETTINGS available, see here: https://ghostscript.readthedocs.io/en/latest/VectorDevices.html#controls-and-features-specific-to-postscript-and-pdf-input. I have quoted that section below, except that I've added the DPI values for each setting in bold, as taken from this table here. You can refer to that table to see the dozens of lower-level settings chosen by gs for each PDFSETTINGS option.

Controls and features specific to PostScript and PDF input

-dPDFSETTINGS=configuration

Presets the "distiller parameters" to one of four predefined settings:

• /screen (72 dpi) selects low-resolution output similar to the Acrobat Distiller (up to version X) "Screen Optimized" setting.
• /ebook (150 dpi) selects medium-resolution output similar to the Acrobat Distiller (up to version X) "eBook" setting.
• /printer (300 dpi) selects output similar to the Acrobat Distiller "Print Optimized" (up to version X) setting.
• /prepress (300 dpi) selects output similar to Acrobat Distiller "Prepress Optimized" (up to version X) setting.
• /default (72 dpi) selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.

You can also see definitions for various options on this page: https://ghostscript.readthedocs.io/en/latest/Use.html:

-dNOPAUSE
Disables the prompt and pause at the end of each page. Normally one should use this (along with -dBATCH) when producing output on a printer or to a file; it also may be desirable for applications where another program is "driving" Ghostscript.

-dBATCH
Causes Ghostscript to exit after processing all files named on the command line, rather than going into an interactive loop reading PostScript commands. Equivalent to putting -c quit at the end of the command line.

-dQUIET
Suppresses routine information comments on standard output. This is currently necessary when redirecting device output to standard output.

Answer 11

I strongly recommend pdfsizeopt.

It is much more efficient in terms of size reduction than any of the previous CLI and GUI software that I have tried (including convert, gs, pdftk, etc.) — although possibly slower with pngout activated —, and does not have some of their issues (no heavily pixelated/degraded images, no loss of metadata such as table of contents, etc.).

Now, if you need to attain a certain size whatever the consequences (inc. degrading images to a point of unreadability), it might not be the tool you need, but as an always-working go-to solution, to reduce unnecessary big sizes in PDFs without loosing in readability, information and acceptable image quality, I think it is the best option. (Note: I tend to use it after having first done a vectorization-OCR in Adobe Acrobat [the function used to be called "CleanScan"], which can have a dramatical size impact on some scanned text documents.)

---

I recommend the generic Unix install:

1. Install all required dependencies:
   • Ghostscript
   • jbig2
   • pngout
   • png22pnm
   • sam2p
2. Download and install the executable:

   curl -L -o pdfsizeopt.single https://raw.githubusercontent.com/pts/pdfsizeopt/master/pdfsizeopt.single
   chmod +x pdfsizeopt.single
   cp pdfsizeopt.single /usr/local/bin/pdfsizeopt
   

Usage:

pdfsizeopt original.pdf [compressed.pdf]

---

Note: for Mac users finding this post (or Linuxbrew users), there is a Homebrew install formula:

brew install --HEAD pts/utils/pdfsizeopt

Answer 12

For me the gs screen option was too bad, and the ebook one too big.

My original document contained text as colour and black and white images (depending on the page).

The best solution I did come up has been:

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dDownsampleColorImages=true -dDownsampleGrayImages=true -dDownsampleMonoImages=true -dColorImageResolution=130 -dGrayImageResolution=130 -dMonoImageResolution=130 -r130 -dNOPAUSE  -dBATCH -sOutputFile=output_lr.pdf input.pdf

Note that the compression level is not linear.. if I was specifying 135 it didn't compressed, I did find 130 to be (in my case) the maximum resolution that achieves a compression.

Answer 13

I just encountered this problem myself. If using simple scan, select text mode for low resolution scans and you won't need to worry about the command line stuff. Just saying.

Answer 14

Control the compression quality:

#!/bin/sh
INPUT=$1; shift
OUTPUT=$1; shift
GS_BIN=/usr/bin/gs
QFACTOR="0.40"

# Image Compression Quality
#
# Quality HSamples VSamples QFactor
# Minimum [2 1 1 2] [2 1 1 2] 2.40
# Low     [2 1 1 2] [2 1 1 2] 1.30
# Medium  [2 1 1 2] [2 1 1 2] 0.76
# High    [1 1 1 1] [1 1 1 1] 0.40
# Maximum [1 1 1 1] [1 1 1 1] 0.15 

${GS_BIN} -dBATCH -dSAFER -DNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=${OUTPUT} -c "<< /ColorImageDict << /QFactor ${QFACTOR} /Blend 1 /HSample [1 1 1 1] /VSample [1 1 1 1] >> >> setdistillerparams" -f ${INPUT}

Answer 15

Since this link was first for me when I searched in Google, I thought I'd add one more possibility. None of the above solutions was working for me on a pdf exported from Inkscape (15 mb), but I was at last able to shrink it down to 1 mb by opening it in GIMP, and exporting as pdf again.

Another option that came close (but text was a little fuzzy) was ImageMagick's convert utility:

convert -compress Zip input.pdf output.pdf

Answer 16

I was facing the same problem, and was glad to find this thread. Specifically I had a pdf generated from scanned images, and needed to reduce its byte size by a factor of 6.

Unfortunately, none of the solutions above worked :(. Then I realized that somewhere in the scanner->jpeg->pdf process the size of the page had gotten bloated by a factor of aprx 4. The documents I scanned were all Letter sized, but the pdf had size of

identify -verbose doc_orig.pdf | grep "Print size"
 Print size: 35.4167x48.7222

I got the desired results finally with a "convert" command that did both resizing as well as compression steps in one:

convert -density 135x135 -quality 70 -compress jpeg -resize 22.588% doc_orig.pdf doc_lowres.pdf

Note that doc_orig had density of 72x72 dpi.

Answer 17

In the end I wrote my own bash script to solve this, it uses mogrify, convert and gs to extract pdf pages as png, resize them, convert them to 1-bit bmp and then rebuild them as pdf. File size reduction can be over 90%. Available at http://www.timedicer.co.uk/programs/help/pdf-compress.sh.php.

Answer 18

If converting to djvu would also be ok and if no colors are involved, you could try the following:

Convert the pdf to jpg files using pdfimages -j

If you get pbm files instead, you should do the intermediate step:

for FILENAME in $(ls *.pbm); do convert $FILENAME ${FILENAME%.*}.jpg ;done

The convert command is from the imagemagick package.

Then use scantailor to make tif's out of it.

In a last step you go to scantailors out direcory (where the tif's are located) and apply djvubind to that directory.

This should reduce the filesize drastically without big quality loss of the text. If you want finer control over the ocr-backend, you may try djvubind --no-ocr and use ocrodjvu to add the ocr layer afterwards.

If you have color's in your document things get a bit more complicated. Instead of djvubind you could use didjvu and in scantailor you have to change to mixed mode and select sometimes color-images manually.

Answer 19

You can try this :

$ time pdftk myFile.pdf output myFile__SMALLER.pdf compress
GC Warning: Repeated allocation of very large block (appr. size 16764928):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 8384512):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 11837440):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 8384512):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 33525760):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 7254016):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 34041856):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 33525760):
    May lead to memory leak and poor performance.

real    0m23.677s
user    0m23.142s
sys     0m0.540s
$ du myFile*.pdf
108M    myFile.pdf
74M     myFile__SMALLER.pdf

It is faster than gs but compresses upto 30% in this case for a 107.5MiB input file.

Answer 20

I use this zsh function for compressing scanned documents:

pdf-compress-gray () {
    local input="${1}"
    local out="${2:-${input:r}_cg.pdf}"
    local dpi="${pdf_compress_gray_dpi:-90}"
gs -q -dNOPAUSE -dBATCH -dSAFER -sProcessColorModel=DeviceGray -sColorConversionStrategy=Gray -dDownsampleColorImages=true -dOverrideICC -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dColorImageDownsampleType=/Bicubic -dColorImageResolution=$dpi -dGrayImageDownsampleType=/Bicubic -dGrayImageResolution=$dpi -dMonoImageDownsampleType=/Bicubic -dMonoImageResolution=$dpi -sOutputFile="$out" "$input"

}

Usage:

[pdf_compress_gray_dpi=100] pdf-compress-gray input.pdf [output.pdf]

Answer 21

I normally simply use

gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -dPDFSETTINGS=/printer \
   -sOutputFile=output.pdf input.pdf

I went through many questions one how to reduce the size of a pdf on AskUbuntu, Stack Overflow and Unix & Linux SE and I wondered what all those options proposed in the answers meant.

Some are Interaction-related parameters:

-dQUIET
-dBATCH
-dNOPAUSE

Some are Device and output selection parameters:

-sDEVICE
-sOutputFile

Some are Common controls and features specific to device PDFWRITE:

-r<resolution>
-dCompressFonts

This important one presets the "Distiller Parameters", Adobe's documented parameters for controlling the conversion into PDF, to one of four predefined settings (screen, ebook, printer, prepress)

-dPDFSETTINGS

All the ones below are automatically preset according to -dPDFSETTINGS, as per this table. A command suggest by Kurt Pfeifle can be used to check these values. You can fine tune them if you want:

-dCompatibilityLevel
-dAutoRotatePages
-dEmbedAllFonts
-dSubsetFonts
-sColorConversionStrategy
-dDownsampleColorImages
-dDownsampleGrayImages
-dDownsampleMonoImages
-dColorImageResolution
-dGrayImageResolution
-dMonoImageResolution
-dColorImageDownsampleType
-dGrayImageDownsampleType
-dMonoImageDownsampleType

Answer 22

load image or even pdf file into inkscape.

From inkscape: Save in vector format (as the native .svg).

Import vector files into scribus, edit layout and export/save as .pdf from there

Answer 23

pdfsizeopt full installation instructions

For my other, gs-based answer, see here.

For anyone trying to follow @iNyar's answer to install and try out the pdfsizeopt tool, installing the dependencies is tricky. If you run the tool without installing all dependencies, pdfsizeopt won't run. Here are the errors I got when trying to run it without jbig2, pngout, and sam2p installed:

$ ./pdfsizeopt in.pdf out.pdf
info: This is pdfsizeopt ZIP rUNKNOWN size=69856.
info: prepending to PATH: /home/gabriel/GS/Jobs/Edge Autonomy/Onboarding [29 May 2023 start date!]
error: image optimizer not found on PATH: jbig2
error: image optimizer not found on PATH: pngout
error: image optimizer not found on PATH: sam2p
error: image optimizer not found on PATH: sam2p
fatal: not all image optimizers found (see above), ignore with --do-require-image-optimizers=no

So, the solution is to install the jbig2, pngout, and sam2p dependencies manually. Here are the full installation instructions, therefore, for pdfsizeopt:

Tested in Linux Ubuntu 20.04.

# ================================================
# 1. Install `pdfsizeopt` dependencies
# ================================================
--------------------
jbig2:
- https://github.com/agl/jbig2enc
--------------------
install dependencies
sudo apt update 
sudo apt install libleptonica-dev
git clone https://github.com/agl/jbig2enc.git
cd jbig2enc
./autogen.sh
./configure
time make

sudo make install
ensure it is installed
jbig2 --version
--------------------
pngout
- http://advsys.net/ken/utils.htm#pngout
- http://www.jonof.id.au/kenutils.html
--------------------
download it
wget https://www.jonof.id.au/files/kenutils/pngout-20200115-linux-static.tar.gz
extract it
tar -xf pngout-20200115-linux-static.tar.gz
cd pngout-20200115-linux-static
install it
sudo cp -i amd64/pngout-static /usr/local/bin/pngout
ensure it's installed
pngout
--------------------
sam2p
- https://github.com/pts/sam2p
--------------------
install dependencies
sudo apt install libgif-dev
go here and find the latest release:
https://github.com/pts/sam2p/releases
Use the correct URL from there in the following commands.
download it
wget https://github.com/pts/sam2p/releases/download/v0.49.4/sam2p-0.49.4.tar.gz
extract it
tar -xf sam2p-0.49.4.tar.gz
cd sam2p-0.49.4
./configure
time make
sudo make install
ensure it's installed by checking its version
sam2p --version
================================================
2. Install pdfsizeopt
================================================
curl -L -o pdfsizeopt https://raw.githubusercontent.com/pts/pdfsizeopt/master/pdfsizeopt.single
chmod +x pdfsizeopt
sudo cp -i pdfsizeopt /usr/local/bin/pdfsizeopt

Now use it:

# 1. Check the help menu to ensure it's installed
pdfsizeopt --help 2>&1 | less -RFX
2. Use it to optimize in.pdf into out.pdf
pdfsizeopt in.pdf out.pdf

Example run and output:

$ pdfsizeopt in.pdf out.pdf
info: This is pdfsizeopt ZIP rUNKNOWN size=69734.
info: prepending to PATH: /home/gabriel/Downloads/Install_Files/pdfsizeopt/pdfsizeopt/pdfsizeopt_libexec
info: loading PDF from: in.pdf
info: loaded PDF of 1955931 bytes
info: separated to 18 objs + xref + trailer
info: parsed 18 objs
info: found 0 Type1 fonts loaded
info: found 0 Type1C fonts loaded
info: optimized 6 streams, kept 6 zip
info: compressed 0 streams, kept 0 of them uncompressed
info: saving PDF with 18 objs to: out.pdf
info: generated object stream of 523 bytes in 9 objects (21%)
info: generated 1953795 bytes (100%)

Result of running pdfsizeopt above: no change. in.pdf is 2.0 MB, and out.pdf is 2.0 MB. Then again, gs, as described in my other answer, didn't work on this particular PDF either. I don't know why.
Note: for anyone who wants to experiment with this, here is how I created the PDF I'm experimenting on:

1. Take 3 photos with your phone (Google Pixel 5 in my case). Let Google Photos upload them to the cloud.
2. Download them into a directory.
3. Run pdf2searchablepdf -c "path/to/dir" on that dir with the 3 images, to perform OCR on them and combine them into a single PDF. You'll see that
   1. My "compressed" PDF output, using gs under-the-hood, did nothing.
   2. All files are the same size, even though one should be large, medium, small, etc.
4. Try to compress them with pdfsizeopt and it does nothing for me on these PDFs as well.

References:

1. @iNyar's answer

2. ChatGpt helped me a ton to figure out how to install a lot of this mess, in particular calling sudo apt install libgif-dev prior to running time make to build sam2p, else I'd get this error:

   g++ -s -O2 -DHAVE_CONFIG2_H   -fsigned-char -fno-rtti -fno-exceptions -ansi -pedantic -Wall -W -Wextra -c gensi.cpp
   g++ -s   sam2p_main.o appliers.o crc32.o in_ps.o in_tga.o in_pnm.o in_bmp.o in_gif.o in_lbm.o in_xpm.o mapping.o in_pcx.o in_jai.o in_png.o in_jpeg.o in_tiff.o rule.o minips.o encoder.o pts_lzw.o pts_fax.o pts_defl.o error.o image.o gensio.o snprintf.o gensi.o -o sam2p
   /usr/bin/ld: appliers.o: in function `out_gif89a_work(GenBuffer::Writable&, Rule::OutputRule*, Image::SampledInfo*)':
   appliers.cpp:(.text+0x2025): undefined reference to `out_gif_write(GenBuffer::Writable&, Image::Indexed*)'
   collect2: error: ld returned 1 exit status
   make: *** [Makedep:66: sam2p] Error 1
   

   All words and commands in this answer are my own, however, and I tested everything in this answer personally.

Answer 24

Super simple PDF compress tool: GitHub page.

Installation on Ubuntu:

sudo add-apt-repository ppa:jfswitz/released

sudo apt-get update

sudo apt-get install pdf-compressor

It uses ghostscript.

Answer 25

I used below commands but it didnt compress my pdf file substantially. Some times some of the portion was blackened after compression.

1. gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf $INPUTFILE

2. "ps2pdf -dPDFSETTINGS=/ebook %s %s" % (input_file_path, out_file_path)

After too much wandering over the web I just couldn't find the right compression library. I came across pdfcompressor.com. This is just awesome website. It compresses the pdf by 95% ( 15Mb of files). So I used selenium and Tor to automate the compression. Checkout my Github Repository. [GITHUB] (https://github.com/gugli28/PdfCompressor)