Theme thumbnails help users quickly identify your theme. It’s especially important to provide thumbnails when your theme offers color schemes.
Here’s how to create a proper thumbnail image for your theme:
Create a thumbnail image. Make sure it’s 150 pixels wide by 120 pixels high. You may want to take a snapshot of your theme and re-size it to these dimensions. Your thumbnail must be these exact dimensions or the image won’t display properly.
Save the image as a
thumbnail.pngand place it in the theme’s
imagesfolder (create this folder if it doesn’t already exist). On redeployment, the
thumbnail.pngfile automatically becomes the theme’s thumbnail.
Now, when you apply the theme, its thumbnail displays along with the other themes that are available to your site.
Congrats! Now you know how to create a thumbnail image for your theme!
Liferay Theme Generator Specifying Color Schemes in Your Theme