The theme will generate several image files automatically, it detects the visitor’s screen size to deliver different size image files.
The following dimensions and specifications are not very strict, but are recommended for reference.
For full width images: the suggested maximum size is 2000 * 2000px (width*height)
For images in col2: the suggested maximum size is 1000 * 1000px
For images in col3: the suggested maximum size is 700 * 700px
For web page loading speed. The image file is better less than 200kb.