how to call back(display) the images which been extracted before?

I've done feature extraction using GLCM and k-nn for classification. What I need to do now is troubleshooting, to analyse why the images been classified wrongly. I want to display the nearest neighbor of the testing data, but not just points like below:

I want to display the images that nearest to that image(test), so that is easy to know why is that the images nearest to each other(visually). But here is my problem, I didn't know how to call back the images which been extracted before, since those are presented in array of numbers only.

What should I do?Please help me