I just did a test for people without Photoshop who cant afford it or are not students :
I like Starac prefer Photoshop for any scaling of textures ( I used to swear by G.I.M.P but now know that PS does a bit of a finer job ) ..
.. However, there is one exception where DDSOpt does shine ( if you get the settings right )
It can do a brilliant job on just Normal maps ( its especially good on redoing the mipmaps )
Here's a before and after comparison, right click and open each in their own tab to flick between the two and compare
( Try to ignore the tiny randomly placed rocks jumping around between loads :) )
The before is with SRO 1.7 no changes
The after is with SRO 1.7 Normals reduced half size with DDSOpt
For my machine, just doing that has brought it into a comfortable range of VRAM use on my 3gb Laptop NVidia 970M card
See previous testing
I dont really need to do any reduction, but wanted to get the average down a little bit more - Reducing just the normals gets me down to an average VRAM use around the game 2.2gb ( without reducing normals I am averaging just under 2.6gb VRAM use )
And for comparison with vanilla, heres another screenshot recently testing the new Skyrim Performance Monitor, just with SSE Vanilla textures, averaging just under 1.7gb VRAM
So for anyone desperate with a need to do any tailoring of the set for their own machines needs with less than 4gb .. I would say the best bet short of buying Photoshop is just to use DDSOpt on only the normal maps, so as not to degrade the diffuse textures
Use the settings in the screenshots here
But for constraints dont use R5G6B5 ( not compatible with SSE, see this topic ), just use all the lossless options for best results, and 50% them all.
If you have difficulty separating normals from diffuse with filtering, just use a command line, xcopy ..
xcopy /S "drive:\pathtofolder\*_n.dds" "drive:\pathtodestinationfolder\"
( The /S makes it go into and copy directories and sub-directories except empty ones )
( The *_n.dds makes it look for any file (* is a wildcard) ending in _n.dds )
Your destination folder will then have all of the normal map textures only to work on.
Starac will probably given time come out with his own quality reduced option set including much better reduced diffuse textures done with PS ( and save reducing some of the lower res normal maps ) to overwrite the full installation with .. If we ask nicely :)
Edited by alt3rn1ty, 04 February 2017 - 05:24 PM.