dhananjaysingh

Using this plugin you can associate one image with each of your category created in wordpress. and you can call that image by using provided function in any template file 
 tejus_dj_getcatimg($catid) 
call this function in any template file it will return url of that image. 
where $catid is category id of that category. 
my facebook profile : https://www.facebook.com/dhananjay.singh2 
my company website: http://tejuscreative.com/

category image

Using this plugin you can add images to categories

MMDeveloper

A wordpress plugin that allows you to add categories to attachments. Similar to https://wordpress.org/plugins/map-categories-to-pages/, but just allows you to set the attachment’s category.
Map Categories to Attachment displays the category box on the “Edit Attachment” page. By default, Every attachment in wordpress is mapped to the default category but this plugin gives the option to select categories for an attachment.
Built by The Marketing Mix Perth: http://www.marketingmix.com.au

category image vs Map Categories To Attachment