How to determine the window version from installation media

Open up a command prompt as administrator and run the following command.

dism /Get-WimInfo /WimFile:I:\sources\install.wim /index:1

(I is the drive letter for the installation media)

There is the output from the command for Windows 8.1 Pro

C:\windows\system32>dism /Get-WimInfo /WimFile:I:\sources\install.wim /index:1
Deployment Image Servicing and Management tool
Version: 6.1.7600.16385
Details for image : I:\sources\install.wim
Index : 1
Name : Windows 8.1 Pro
Description : Windows 8.1 Pro
Size : 13,401,658,686 bytes
Architecture : x64
Hal : acpiapic
Version : 6.3.9600
ServicePack Build : 17415
ServicePack Level : 0
Edition : Professional
Installation : Client
ProductType : WinNT
ProductSuite : Terminal Server
System Root : WINDOWS
Directories : 19668
Files : 106881
Created : 22/11/2014–20:23:51
Modified : 22/11/2014–20:25:07
Languages :
zh-HK (Default)
The operation completed successfully.
C:\windows\system32>