on Just Publishing Advice:
Free image optimization tools make the job of preparing your images for publishing a quick and easy task.
When you plan to use images for your blog, your ebook, or anywhere online, you need to make sure you resize and compress your images.
You might use images from your camera, phone, or free stock images. But the original dimensions and file sizes will always be too big to use.
Luckily, it’s easy to make sure you optimize your images to remain sharp and clear and use the smallest file size possible.