Images used on websites and in ebooks should be compressed.
But compressed does not mean reduced in size.
When an image is compressed, it retains its physical dimensions. But it is stripped of its embedded data, and the resolution and quality are both lowered to reduce the file size.
As with all things Internet, including ebooks, smaller file sizes make for faster websites and transfer speeds.
If you are publishing on Amazon Kindle and use images in your ebooks, large image files will increase your overall ebook file size. You are charged for ebook delivery by Amazon, so be aware that large ebook file sizes will quickly eat away at your royalty.
The key to image compression is to find the right balance between image quality and file size to suit where the image will appear. For a website, an image does not need to be of high quality and resolution, but it still needs to be sharp and clear.
For an ebook, consider that it is unlikely that your ebook will be read on a high-definition device. A Kindle ebook reader is certainly not, and many models are only black and white. So again, high resolution is definitely not necessary.
How to compress an image
Before compressing an image, the most important step is to change the physical dimensions of the image to suit where you are going to use it.
But first, make a copy of your image so you can keep the original.
Then you can use Preview on an Apple or Paint on a PC to resize the copied image to the size and resolution you want. Save your resized image.
There are many ways to compress a jpeg image or png images online, and a quick Google search will find a lot of free sites that mostly work very well.
I will use Online Image Optimizer for my example below.
My original image is nearly 1.4 megabytes, which is far too big for online use. So let’s look at how to use lossy compression to compress the image size and make it suitable to use on a website or in an ebook.
The great feature if this tool is that it gives you a long list of choices at each stage of more and more compression.
As you scroll the down image below, look at the file size on the left of each image, which is reducing with each slide.
Depending on how you intend to use an image, the last three optimized images still retain enough visual quality to be used for most online applications. But with a saving of over 80% on the original file size.
However, in the last image, it is noticeable that the quality is starting to deteriorate. I would select the third from last. All I need to do is right click on my selected image, and download it.
That’s it. I now have my image at a fraction of its original file size, but without any visible loss of quality or dimension.
Can you compress offline?
If you have an Apple computer, a quick and easy way to compress an image is to use a free application, ImageOptim.
It is a simple drag and drop application. You can adjust the settings to suit any level of compression for jpeg, png or gif.
Image compression is quick and easy. It saves on bandwidth which reduces the loading speed of websites and blogs.
For ebooks, compressing all your images will reduce the Whispernet delivery charge by Amazon Kindle. So your royalty will be higher.
These are both very good reasons to learn how to compress images. It’s easy to do, so make a habit of compressing all of your online and ebook images.
What do I use?
For every image that I add to my websites or ebooks, I use ImageOptim because it is so quick and easy. You can see my settings for it in the image above. All I need to do is drag the image file into the app and it’s all done in less than a second.
But I have one more tool to compress images even more that I use for all my websites.
WP Smush is a free WordPress plugin that compresses images automatically on upload to the WordPress media library.
While it doesn’t do as good a job as ImageOptim by itself, it helps by reducing my already compressed images just a little bit more. Again, without any quality loss, which ensures that my website pages will load lightning fast.
If you only want a compressed version of your book cover to use on your website, go to your book’s Amazon page and right-click on your book cover image and download it.
You will get a fully compressed version because Amazon has done all the compression work for you.
More reading: How To Use Google Reverse Image Search To Your Advantage