Man! This is a really quick post!..
What is your problem? Something as…
property typesList : {"..CT", "8BPS", "BMP ", "BMPf", "EPSF", "EPSP", "GIFf", "JPEG", "PCX ", "PCXx", "PICT", "PNGf", "PNTG", "SGI ", "TIFF", "TPIC"}
set theFileListFolder to choose folder with prompt "Choose a folder with images."
tell application "Finder"
set theFileList to {}
repeat with i in typesList
set theFileList to theFileList & (files of entire contents of theFileListFolder whose file type is (i as string))
end repeat
end tell
property theFileTypes : {"..CT", "8BPS", "BMP ", "BMPf", "EPSF", "EPSP", "GIFf", "JPEG", "PCX ", "PCXx", "PICT", "PNGf", "PNTG", "SGI ", "TIFF", "TPIC"}
tell application "Finder"
activate
set theFileListFolder to choose folder with prompt "Choose a folder with images."
set theFileList to get every file of entire contents of theFileListFolder whose file type is in theFileTypes
end tell