Loop Image Directory, Just want Images

 I am trying to figure a way to do this but can't come up with a solution for some reason. I am trying to display random images from directoires. here is what i have so far.
  
Dim strImgLeft As String() = Directory.GetFiles(Server.MapPath("~/images/imgLeft/"))
Dim strImgRightPeople As String() = Directory.GetFiles(Server.MapPath("~/images/imgPeople/"))
Dim strImgRightPartner As String() = Directory.GetFiles(Server.MapPath("~/images/imgRightT/"))

Dim r1 As New Random
Dim r2 As New Random
Dim r3 As New Random

Dim fi1 As New FileInfo(strImgLeft(r1.Next(0, strImgLeft.Length)))
Dim fi2 As New FileInfo(strImgRightPeople(r2.Next(0, strImgRightPeople.Length)))
Dim fi3 As New FileInfo(strImgRightPartner(r3.Next(0, strImgRightPartner.Length)))

Im ...