This is a Python program I wrote for fun to apply linear algebra theory I learned in Monash uni. The code uses singular value expansion method to reduce the size of an image. Here are compression examples, featuring my cat Marmite.

First, install Python. Next, install dependencies:

pip install numpy
pip install imageio

Finally, download the code of the image compressor (requires git):

git clone https://github.com/evgenyneu/image_compressor_python.git
cd image_compressor_python

Compress an image file marmite.jpg using ten terms of the singular value expansion:

python src/compress.py marmite.jpg --terms=10

It creates an image named marmite_10_terms_25.0x_compression.jpg that looks like this:

You can experiment with the --terms option and see how it affects the image quality and compression ratio.

  -h, --help            show this help message and exit
  --output OUTPUT       path to the compressed image that will be created
  --terms TERMS         number of terms in the singular value expansion
  --iterations ITERATIONS
                        number of iterations of the power method
  --notext              do not put text on the image

This following program allows to compress many images with different quality all at once. This can be useful for comparing many different outcomes and see how the terms setting affects image quality:

$ python src/process_samples.py INPUT_DIR OUTPUT_DIR

Replace INPUT_DIR with the name of directory that contains images you want to compress, in JPG, PNG or BMP format. All images in the directory will be compressed.

Replace OUTPUT_DIR with a name of the directory where you want compressed images to be placed.

This example uses the images from images/for_compression directory:

$ python src/process_samples.py images/for_compression images/compressed/

Creating images:
images/compressed/100x100/marmite_100x100_1_terms_49.8x_compression.jpg
images/compressed/100x100/marmite_100x100_2_terms_24.9x_compression.jpg
images/compressed/100x100/marmite_100x100_5_terms_10.0x_compression.jpg
images/compressed/100x100/marmite_100x100_10_terms_5.0x_compression.jpg
images/compressed/100x100/marmite_100x100_20_terms_2.5x_compression.jpg

The program produced the following compressed images featuring my cat Marmite. The image are 1000 by 1000 pixels. The compression results for images of different sizes are located here.

Install pytest

pip install pytest

and run the unit tests:

pytest

This work is in public domain.