How To Lower Texture Resolution Case By Case?

So I'm trying to make a slideshow, that's all been peachy, but the thing is I want to have a very large number of images which can be sorted through, so I made a page to display all the images at once, the problem is that I'm worried about performance on that page. I have no idea how to load the images in chunks so for now my best hope is to have them all appear at lower resolution. I only want them to appear lower resolution on that specific page though since I want them to be the highest resolution possible when they're actually displaying in the slideshow.

TL;DR, How to I instantiate images in low resolution for one scene, and the same images in high resolution in another?