How to add a different specific image for each page in a region?
I assume that you have a content type which contains the field image and that image field have to displayed randomly in different pages. If so the solution would be


Create a block view and add the content type as criteria and the field:image
Remove all sort criteria and just add Global: Random as a sort criteria 
specify only one content should be displayed in Pager option


That's it. Now you can render it and it will randomly display the image in each page