I've read that it is important to have smaller image sizes. Of course this is logical, having larger images will result in a bigger data transfer wich is slowing down your website. Somewhere in 2014 I followed a webinar of Daniel Kanchev about speeding up your Joomla-website, and he also mentioned the optimalisation of images via smush.it of yahoo.
Not so long ago i read a tweet from Brian Teeman where he mentioned a blogpost of his about compresso.io. On this website you can optimize images for use on the web. Now I also wanted to test some of mine images. I took four images I used on my site, to see if and what the optimalisation would offer me.
| File | Original | smush.it | compressor.io | |
|---|---|---|---|---|
| Image 1 | jpg | 23 kB | 21 kB (-8,7%) | 19 kB (-17,4%) |
| Image 2 | png | 161 kB | 111 kB (-31,1%) | 47 kB (-70,8%) |
| Image 3 | jpg | 155 kB | 144 kB (-7,1%) | 61 kB (-60,6%) |
| Image 4 | jpg | 54 kB | 51 kB (-5,6%) | 53 kB (-1,9%) |
| Image 5 | png | 326 kB | 270 kB (-17,2%) | 86 kB (-73,6%) |
In this limited test you can see some big differences. When the file size is already small the optimalisation doesn't do much. If the file is already a bit larger than you can have some nice results, in my case especially using .png.
So my conclusion is, you should try compressor.io if you can get a smaller image size.