I've made the below modifications to your codebase and I'd be happy to send you my code if you'd like.
In my code..
--> On the Manage Images page (in the administrator panel) there is now a small thumbnail image next to each entry.
--> On the Manage Images page (in the administrator panel) there are now 25 entries displayed at one time instead of 5. This avoids the need for clicking on "Next" several times to find an image.
--> images with either lowercase file extensions OR uppercase file extensions can be uploaded to the image slider.
--> The default code behavior is for the image slider to scale up or down in size depending on the user's device width. This doesn't work too well when 8 images are displayed for example on an iPhone.
A better solution (in my opinion) is to simply display fewer images based on the user's device width - and not scale everything up or down in size.
Again I'd be happy to send you my code for the above modifications.