(Spoiler alert: this program is only available for Windows)
I believe it to be a hard and fast fact that people like to look at pretty pictures.
Which isn’t the best news for an author like me. I’m not sure if neuroscience backs this up, but I think the brain processes the message of pictures faster and easier than a sentence that describes what the picture is saying. For instance, an image of a Labrador fresh out of a pond and shaking off water in bright sunshine with a child laughing next to him conveys more information and emotion than I could in three paragraphs.
I guess someone else realized this and invented advertising.
A successful website should have lots of images. Bright, colorful, and eye-catching. Unfortunately the better the jpg (Joint Photographic Expert Group, the people who created the standard for lossy graphics files) image the bigger the file size (which is measured in bytes). Bigger files take longer for a server to load and send to the viewer, which makes your website run slower. Which makes Google sad.
Luckily there’s an answer.
Jpg images have a lot of extra room that can be eliminated using programs called image compressors. These algorithms make small reductions in format that makes the files smaller without losing too much definition. There are several good, free online image compression plugins that you can install on your WordPress site, such as Smush (the one I use). These run automatically when you upload an image and reduce the size by quite a bit.
However, I prefer to optimize my images before I upload them using Caesium Image Compressor (sorry, it’s just for Windows). This free image compressor has a great user interface that lets you lets you easily control the compression level and preview it real time, then quickly compresses even the slightly bloated by over 50% with no discernible loss of quality. I then send the files to a staging file for uploading to my website.
In the example in the screenshot below (which Caesium reduced by 9%), you’ll see the results of Caesium offline image compressor run on a group of product images. These pictures were taken by a professional who sent them to me in huge 4000px X 4000px jpg formats, which Caesium reduced by 87% – 99% with almost no loss of quality (note: my reduction was 50%).

Can we run an image compressor on WordPress as well?
It’s your choice, but I usually keep Smush deactivated because compressing files that have already been compressed can result is serious loss of quality. I also usually don’t compress PNG files because the results come back distorted. Although I am tempted to try the awesomely named Compress-Or-Die PNG Compressor.
Verdict?
Total love for Caesium Offline Image Compressor. I want my site serving beautiful images fast, and I’m very happy that it is free (but buy the developer, Matteo Paonessa, a coffee. He deserves it).