I created a brand new site collection and uploaded a .jpg file in the document library did a full crawl and when I searched for the .jpg file. I could see it in the search results but I am not able to preview the image when I mouse over on the link instead it is showing author name etc.
How to preview the images .JPG on the search result page in SharePoint 2013.
You need to some sort of customization, in order to see image preview in search result.
The solution is to modify the hover display template that is being used for default items. This can be easily performed using SharePoint Designer 2013.
Check this blog post for complete steps & code:
Use an Image Library or an Asset Library. Images don't render thumbnails from a Document Library by default. You have to mess with the display templates if you use a document library.
