Compressing images

As this site is now hosted on Github Pages, there is a limit of 1 GB of total storage size. Realistically it would take a looong time for me to reach that limit, but it’s good practice to compress your stuff properly anyway. Fetching an 800kb image as part of the site load is annoying.

I am using these to compress images:

• ffmpeg for JPG compression
• pngquant for downsizing PNG color palettes of screencaps
• ImageMagick for miscellaneous image tasks

This article on Gitlab is an interesting read.

I wrote a short script to automate compressing images for an article, but it still needs some work. I used counting colors as means of detecting graphics that will compress well using the color palette downsizing, but it doesn’t seem to work well in all cases.

A couple of notes:

• shopt -s nullglob makes bash not freak out when it doesn’t find any files matching given glob pattern
• using zopflipng gives ~10% storage saving tops, which on this scale is not worth spending several seconds to compress each image
• scale=w=min(iw\,800):h=-2 downcales image to 800 width if it’s wider and preserves aspect ratio by downscaling height but making it an even number