check file exists or not in folder in php

[TerryD]

i want to know how to check the filename in folder with some condition.for example :the folder name is "output"this folder containing the following the images.2323a.Png5235v.Jpeg2323s.jpg23523s.JPEGetc..,if i check the file name is "2323a.png" but there is file name is 2323a.Png.how to i check the filename is incasesensitive.thanks in advance