"The cover image is considered the primary preview image to present your file and is required at the set dimensions/aspect ratio listed above. We know that one image isn’t enough to show off your product so you can include up to 15 preview images.
Including preview images is optional, but if you are including one, please follow these guidelines:
We highly recommend you to include 3 or more for best results on the item upload page.
The previews can be of varying size however we recommend the same aspect ratio and dimensions as the cover image for best results.
" The cover image is your primary preview image which will be displayed as the first image shown on your item detail page and in the search results. Alongside your main cover image, you’ll also be able to include a series of preview images as outlined in the next section below.
In an effort to present your items in the best way possible, Envato offers cover images that are larger than what’s traditionally found on digital marketplaces. We realise this is more work for you as an author however the end result will lead to your products looking as good as possible leading to more exposure of your items.
Please review the following requirements below to get started!
The cover image must be provided at these dimensions at the minimum:
Cover images must have a 3:2 aspect ratio
Recommended Dimensions: 2340px (W) x 1560px (H)
Minimum Dimensions: 1170px (W) x 780px (H) - aspect ratio 3:2"
I am confused didn’t find the minimum size for preview image
is cover image is a main preview image?
590 pixel wide JPG preview of your file. The recommended height is 700 pixels. The maximum height is 8000 pixels. If you need more previews for your item, please consider uploading an optional Preview Image Set.
The above you are talking is about- Field:Preview Image Set