Compress scanned handwritten notes with Noteshrink

You scan your handwritten notes, but the quality isn’t great and the file is way too large. The solution: Noteshrink.

This assumes your notes are already in .pdf format.

1. Install Noteshrink

It’s best to install it in a Python virtual environment:

pip install noteshrink

2. Configure ImageMagick (if needed)

On some systems, you may need to adjust ImageMagick’s security policy to allow PDF handling:

nano /etc/ImageMagick-6/policy.xml

Find the PDF line and change:

rights="none"

to:

rights="read|write"

It should look like this:

<policy domain="coder" rights="read|write" pattern="PDF" />

3. Convert the PDF to images

Convert each page into PNG files:

pdftoppm notes.pdf page -png

4. Improve the images

4.1. Increase contrast

find . -type f -name "*.png" | parallel convert {} -sigmoidal-contrast 10,200% {}

4.2. Reduce number of colors

find . -type f -name "*.png" | parallel convert {} -level 50%,50% {}

Note: In ImageMagick 7, convert is replaced by magick.

5. Compress with Noteshrink

Finally, compress everything and generate the optimized PDF:

noteshrink -w -g -O -C -Q -o notes-compressed.pdf *.png

6. Result

The resulting notes-compressed.pdf will be much smaller than the original because:

• It reduces the number of colors
• It fades or partially removes the background
• It improves the readability of handwritten content

With this process, you can turn heavy, low-quality scans into much lighter and cleaner documents.