mirror of https://gitlab.com/curben/blog
119 lines
3.2 KiB
Markdown
119 lines
3.2 KiB
Markdown
---
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title: Make PDF files smaller
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excerpt: Convert to grayscale and reduce the resolution.
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date: 2019-01-05
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tags:
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- pdf
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---
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The most effective ways of reducing the file size of a PDF is by converting to grayscale and reduce the resolution.
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Requirement: ghostscript (installed by default in Ubuntu)
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## Single PDF
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Save the following script as "pdfcompress.sh".
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Usage: `sh pdfcompress.sh input.pdf`
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The output compressed file is named as "input.compressed.pdf"
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```bash
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#!/bin/sh
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filename=$(basename "$1")
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dir=$(dirname "$1")
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gs \
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-sOutputFile="$dir/${filename%.*}.compressed.pdf" \
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-sDEVICE=pdfwrite \
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-dPDFSETTINGS=/ebook \
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-sColorConversionStrategy=Gray \
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-sColorConversionStrategyForImages=/Gray \
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-dProcessColorModel=/DeviceGray \
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-dCompatibilityLevel=1.4 \
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-dNOPAUSE -dBATCH -dQUIET \
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"$1"
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```
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Options ([more info](https://ghostscript.com/doc/current/Ps2pdf.htm#Options)):
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- Remove **ColorConversionStrategy**, **ColorConversionStrategyForImages** and **ProcessColorModel** lines to retain colour.
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- **PDFSETTINGS**:
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- */default* selects output intended to be useful across a wide variety of uses. 72 DPI.
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- */screen* selects low-resolution output similar to the Acrobat Distiller "Screen Optimized" setting. 72 DPI.
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- */ebook* selects medium-resolution output similar to the Acrobat Distiller "eBook" setting. 150 DPI.
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- */printer* selects output similar to the Acrobat Distiller "Print Optimized" setting. 300 DPI.
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- */prepress* selects output similar to Acrobat Distiller "Prepress Optimized" setting. 300 DPI.
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## PDFs in a folder
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Use the following script to compress all PDFs in a folder.
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Usage: `sh pdfcompress.sh 'target folder'`
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*If `'target folder'` is not specified, defaults to current directory.*
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```bash
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#!/bin/sh
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if [ -n "$1" ]; then
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cd "$1"
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fi
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for i in *.pdf; do
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[ -f "$i" ] || break
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# Skip compressed PDFs
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echo "$i" | grep --quiet ".compressed.pdf"
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if [ $? = 1 ]; then
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gs \
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-sOutputFile="${i%.*}.compressed.pdf" \
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-sDEVICE=pdfwrite \
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-dPDFSETTINGS=/ebook \
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-sColorConversionStrategy=Gray \
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-sColorConversionStrategyForImages=/Gray \
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-dProcessColorModel=/DeviceGray \
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-dCompatibilityLevel=1.4 \
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-dNOPAUSE -dBATCH -dQUIET \
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"$i"
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fi
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done
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```
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If you prefer to use the original filename as the compressed version and rename the original uncompressed's to "*.original.pdf",
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*Following script doesn't skip previously compressed PDFs*
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```bash
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#!/bin/sh
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if [ -n "$1" ]; then
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cd "$1"
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fi
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for i in *.pdf; do
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[ -f "$i" ] || break
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# Rename original file to *.original.pdf
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original="${i%.*}.original.pdf"
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mv "$i" "$original"
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gs \
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-sOutputFile="$i" \
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-sDEVICE=pdfwrite \
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-dPDFSETTINGS=/ebook \
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-sColorConversionStrategy=Gray \
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-sColorConversionStrategyForImages=/Gray \
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-dProcessColorModel=/DeviceGray \
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-dCompatibilityLevel=1.4 \
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-dNOPAUSE -dBATCH -dQUIET \
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"$original"
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done
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```
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<br/><br/>
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Source: [Internal Pointers](https://www.internalpointers.com/post/compress-pdf-file-ghostscript-linux), [firstdoit](https://gist.github.com/firstdoit/6390547), [ahmed-musallam](https://gist.github.com/ahmed-musallam/27de7d7c5ac68ecbd1ed65b6b48416f9), [Ghostscript Docs](https://ghostscript.com/doc/current/Ps2pdf.htm)
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