There are plenty of websites where you can find images to use with your themes and websites you create. Some are super expensive, some are not that expensive, some are free but not for commercial purposes, some are free but you need to get permission from the owner or the picture, some require attribution, and some it seems that the way they make money is by unleashing their attorneys demanding ridiculous amounts of money from those who illegally use the images. Really, it seems that their real business is suing people, and not selling pictures.
The website that I use to get my images is Pixabay. Their homepage says “Free images and videos you can use anywhere”, and “All images and videos on Pixabay are released free of copyrights under Creative Commons CC0. You may download, modify, distribute, and use them royalty-free for anything you like, even in commercial applications. Attribution is not required.” Furthermore, they have high resolution images, transparent png files, and even videos.
Now you can download all the high resolution images you want and simply add them to your themes, posts, pages and sliders as they are, but that is the absolute wrong and amatuer way of doing things. Before using the images in any way for the internet, you have to first size it appropriately, and optimize it for the internet, thus reducing the file sizes of the images, without further changing the dimensions and the quality of the images. An you have to remember this too. It is ok to downsize the dimensions of an image, but you should never increase the dimensions of those images.
Most images will be jpgs, and there aremany tools, and even free online tools to help you optimize those images. I have found that Photoshop is the best software to do the job. No other software that I have tested can reduce the filesize of an image without any “visible” quality loss. For batch resizing, renaming and optimizing I use FastStone, which is free for home users.
Now that I have all that out of the way, I want to concentrate on png images. Png files are usually large, and there are hardly any tools that can effectively reduce their file sizes. The exception to this is a free online tool at compresspng.com. The automated script does an ok job in optimizing the png files, but you can and should go into the settings and reduce the number of colors, resulting in very small file sizes, without affecting the quality of the images much. I consistently manage to reduce png files 10 fold.
Also note that, when Artisteer exports the themes, the images aren’t optimized. A typical header image can be over 150kb, and if you use any transparencies, therefore the header’s background image is a png file, can be as large as 800-900kb. If you leave those images untreated, the site will run slower, and Google will penalize you.
I have a short video downloading a png file from Pixabay, resizing it in photoshop, and optimizing it online. The original downloaded image was 1920 x 1009 pixels, with a file size of 1.54MB. The resized image was 571 x 300 pixels, with a filesize of 269kb. Finally after optimizing the image, the resulting image with no visible quality loss was 571 x 300 pixels, and only 36.3kb.