Best practice for detection of image-file; PHP in a snippet or TV with IF query?

I have a page where there can be from one to seven of up to seven pictures in this structure:

folder1/folder1Image1.jpg
folder1/folder1Image2.jpg
folder1/folder1Image3.jpg
....
folder2/folder2Image1.jpg
folder2/folder2Image2.jpg
folder2/folder2Image3.jpg
....
and so on...

What would be the best practice to detect which of the image files that exist, with regard to server load, number of requests between browser and server etc. ?

A php - if file exist - than show file - if not - echo file doesn’t exist?

Or

An Image-Template Variable with an [[!If TV then etc... if not, show message]], seven times on the page?

MODx 2.05pl
Apache on Linux
MySQL