Using DDS Textures in GIMP 2.8

How to open, edit, export, and save textures (for Bethesda games - Skyrim specifically) using GIMP 2.8
> Includes easy-to-understand explanations and helpful advice for newcomers and pros alike.

Introduction

This guide is for anyone wanting to edit textures in Skyrim, though it should work for the two previous Elder Scrolls games, as well as some other Bethesda titles like the Fallout series. A lot of the information I found online was vague, incomplete, or sometimes incorrect. And some of the mistakes that I made because of this required lots of work and experimenting to find / fix.

So here's a step by step guide (it's my first actually)

It'll not only tell you what to do, but why - so you can learn a little about how Skyrim and other (Bethesda) games work, and be more equipped when a problem comes along.

You can skip the rest of this introduction, if you just want to get started.
But it might have some useful information for you.

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GIMP 2.8

GIMP (GNU Image Manipulation Program) is an image editing program, much like photoshop; except that it's FREE. It's easy to use, and I find it more "adjustable" than photoshop. So for a knob twiddling maniac like me, that's a great thing. The more options, the merrier.

You can get it for Windows, OS X, and Linux here: https://www.gimp.org/
Please donate, even just a little, to the creators. Their tireless work has created a great program for people to try out, before / instead-of hefting wads of money at Adobe.

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Types of Textures (in Skyrim)

Skyrim has four types of textures.

• Diffuse Maps: These should be familiar to everyone. They're the colours that coat every "thing" in Skyrim. Without these, almost everything would be invisible. This will be the kind of texture you edit most often.
  
  
• Specular Maps: These are the reflection textures. They're just grey-scale images. The black areas will not reflect, and the white areas will be mirror-like to light sources. If you're using an ENB, you can adjust their strength and 'curve' to make things look more glossy or matte. Their filenames should be the same as the diffuse maps, but usually have "_s" at the end.
  
  
• Glow Maps: These are additive textures; meaning that they only ever increase brightness of what they cover. Only a few vanilla objects use this, like the Vampire eyes, and Nirnroots. Edit these sparingly, as it's easy to make them blinding-ly bright (especially if you use an ENB). Their filenames should be the same as the diffuse maps, but usually have "_g" at the end.
  
  
• Normal Maps: These allow the lighting engine for Skyrim (or your ENB) to add correct lighting and shading to objects. This texture is created by the 3D model being lit from different angles by a certain colour on each axis. From this map, the engine can then determine how the in-game light sources affect the object based on what coloured parts are exposed. I don't suggest editing these in GIMP unless you're doing small fixes (like removing details/mistakes). Their filenames should be the same as the diffuse maps, but usually have "_msn" at the end.

Low poly? No problem?

POTENTIAL "BLOCKY FACE" FIX:

If you find that your characters in Skyrim have blocky / pixelated faces in certain lighting or camera distances; and Skyrim.ini tweaks haven't fixed the problem for you, then an incorrectly exported Normal Map might be the culprit (it was for me - and took me AGES to find).

By opening and re-exporting your Normal Map with new mipmaps, you may fix the problem. Continue reading for how to open and export textures with new mipmaps, and to learn what mipmaps even are.

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1. Installation

First thing's first. You'll need to get GIMP, and you'll need to get the .DDS plugin for it. Both are completely free, and easy to set up.

Visit https://www.gimp.org/downloads/oldstable/

Then download and run the installer for GIMP 2.8 It works for both Windows 32 and 64 bit.

Once installed, you'll need the plugin. Click the link below and save the latest "binaries" ZIP file that matches your system (i.e. 32bit OR 64bit): https://code.google.com/archive/p/gimp-dds/downloads
The zip file will contain an EXE file which you should extract and move to the plugins folder for GIMP.

Unless you changed the default location, that plugins folder should be here:
C:\Program Files\GIMP 2\lib\gimp\2.0\plug-ins

2. Opening the DDS file

When opening a DDS file with GIMP, you'll be given a few options.

I suggest that you untick "Load mipmaps", as it is easiest to edit the high resolution texture, and let GIMP create new mipmaps for you when exporting. But if you know how to use GIMP, there's no harm in creating your own manually from the 'master' layer, halving the dimensions as you go. Doing this will also allow you to chose how small the minimum sized texture will be, so if you have no mipmaps, Skyrim will just use the full sized texture (not a good idea unless you have lots of VRAM).

But what are mipmaps?

They're the smaller versions of the texture, which Skyrim will use as the camera moves further away. So if you really wanted, you could have different colours for each Diffuse mipmap, and watch things change colour as you approach them.

3. Editing (Optional)

This step is optional - as if you are just re-exporting a texture, I doubt you'll need to edit anything.

If you've never used GIMP or Photoshop before, then this guide isn't the place to learn. But don't worry, there are many tutorials out there; both video guides on YouTube, and step by step text & image guides like this one.

You can also ask me questions if you are still stuck - as I'm quite skilled in GIMP (and Photoshop)

Don't feel afraid to experiment with tools and filters. Just make use of the undo button, and to have a backup of the original texture too.

Note:

You might want to increase the amount of undo memory and levels you have, which you can do here. GIMP will make sure that you always have the minimum number of undo levels that you specified, otherwise it will stay limited to your maximum undo memory setting.

This means that if you set it to 100, you will always be able to undo at least 100 times. I suggest setting the "Maximum undo memory" to no more than half of your RAM. Do not worry though, if GIMP is near filling of the space you allowed it to use, it will store undo levels on your drive (in the Swap folder), which can be specified in the "Folders" branch, at the bottom of the Preferences tree menu (in case you have a small SSD you want left alone).

4. Exporting / Saving

As you can probably tell from the title, exporting and saving are different.

Saving (Optional)

If you want, you can save your work as well as exporting. This will let you keep a full quality copy of all the layers (if you're using more than one). You have the option of using the GIMP project format .xcf, or a few others including the Photoshop project format .psd. Alternatively, you can export the image as a high quality PNG for later edits, but your image will be reduced to one layer, so you'll have to generate Mipmaps again if you want them.

Exporting:

Exporting will let you save your work as an image file. In our case, the DDS file for Skyrim.

When exporting, replace the original file unless you want to save it somewhere else (like if you opened a vanilla race skin texture to edit it for a custom race). Then decide what quality you'd like.

Compression: It's best to choose "BC3 / DXT5" compression. As it will reduce the filesize of the texture, but keep the alpha channel (transparency) for various textures that might need it, like fur and hair. But for high quality things like faces and any *Normal Maps, I suggest that you choose "None" for a nearly lossless file.

Mipmaps: If you want to have Mipmaps (you can go without them if you have lots of VRAM), select "Generate mipmaps" on the exporting window. But you NEED to have combined all your layers first. You can do this by right clicking on any layer, clicking "Merge Visible Layers", and then selecting "Clip to Image".

Advanced Options: If you chose to use compression, then expand this section and tick the "Use perceptual error metric" box to improve the compression quality slightly.
NOTE:

*Exporting Normal Maps without compression is essential! Because of the wide range of colours, GIMP (and Photoshop) will ruin their quality (most noticeably in the mipmaps) if you use ANY compression.

If you have a BLOCKY face that you can't fix, opening the file without loading mipmaps, and exporting the file with new mipmaps (and without compression) might be the cure. It was for me.

5. Checking and Re-Editing

If you're like me, you'll probably be making many edits to your textures and checking them in-game.

So with that in mind, here is the fastest way to check, edit, re-export and re-check your textures; without having to waste time closing and reopening Skyrim (as loading another save will not reload textures). You'll need to be able to run both GIMP and Skryim together of course; so if you've no way to switch applications or your computer isn't powerful enough, this method won't be possible.

There's little harm in trying though, as long as you've saved. At worst, one of the two will crawl/crash.

1. Check your texture in-game (obviously).
   
   
2. Once deciding to make a change, save your game and Exit to the Main Menu.
   
   
3. Switch to GIMP and edit the texture as you desire.
   
   
4. Hold [Ctrl]+[E] to overwrite the last file you exported.
   (If your first edit didn't show up, you might be using the wrong filename/location).
   
5. Switch back to Skyrim, and load the save you just created.
   (You could load another save, but you'll need to be able to see your texture, right?)
   
6. Repeat as needed until you're satisfied

Conclusion

Well, that's all there is to it really. Best of luck to you all and sorry this guide is so long! I just wanted to cover all the bases:D

Feel free to ask questions and give feedback (even complaints).
I'll help any way I can, and whenever I can. My knowledge only goes so far, as does my free time.

[₸ʌʟwıcĸ]

Cheers for the info BinToss! I've not modded DDS files in a long time and must have missed that in the release notes for GIMP 2.10 back when I upgraded to it. Good to know support is built-in now. I'll update the tutorial sometime but I'm swamped with work these days.

[BinToss]

GIMP plugins (*.exe/*.dll/*.py) are to be copied to "%userprofile%/AppData/Roaming/GIMP/2.10/plug-ins" and *.scm scripts belong in "%userprofile%/AppData/Romaing/GIMP/2.10/scripts".

[BinToss]

GIMP 2.10 has built-in support for DDS formats from DXT1 to BC5. For BC6 and BC7, you'll need to add scriptkitz/gimp-plugin-dds [github.com] until GIMP officially supports these DDS formats.

[₸ʌʟwıcĸ]

You're most welcome, and good luck! Feel free to ask more if you get stuck - I'll help if I can.

[Cadman013]

Thank you again. That does shed some light on it.

Don't try to download the game in the conditions you have to tolerate, that would be a terrible imposition on you.

[₸ʌʟwıcĸ]

Hey Cadman013, thanks for getting in touch and for your kind words - I really appreciate them.

It's been a long time since I wrote the guide but I'd be happy to help. I never encountered the brown face glitch myself but did a little looking and found it seems to be a problem with the facial presets, so editing 1 texture may not help.

I did find this mod on the Nexus (a site I use regularly, starting with Skyrim) which claims to fix it, but it seems like a tricky workaround using AutoHotKey (a useful program in general - I turned my caps lock into a play/pause key as I never need it). I hope it may help:

https://www.nexusmods.com/fallout4/mods/30080

Otherwise, if you still wish to edit the textures, here's a little help.

Sadly I'm currently stuck in lockdown in a remote area and our internet is abysmal. So it may take days to download Fallout4 - to check the files to find the original compression, dimensions and PPI/DPI.

[₸ʌʟwıcĸ]

But from my memory of Skyrim and its engine (used in FO4), only the first mattered, and it was more often about quality rather than compatibility. Resolution/PPI shouldn't matter as the textures will stretch to fit.

As long as - when stretched - everything fits the faces of the 3D mesh - you can have any size and even ignore matching the aspect ratio (though it may look odd with granular textures like skin pores). Generally textures are square though, so you can go up through multiples of 8 like icons do (i.e. 256x256, 512x512, 1024x1024, etc).

I find it easiest to open the original texture and use them as a guide as you work over them in a new layer. You can scale the whole image first if you want a higher/lower resolution.

I hope this helps! Let me know if not.

[Cadman013]

Talwick, thank you for taking the time to write this tut in a thorough, fully explained way. Explaining all the why questions is what I look for in a tut. Too many just say click this then that, etc but never explain why or how that particular feature works.

Its not very likely I can apply what I learn to a similar objective without knowing what is taking place in Gimp on each step. Your tut has answered a lot of Gimp handling of dds file questions I have.

I have a request.

I don't play Skyrim, but am into Fallout4. Been learning all I can about using mods and some mod editing nearly a year now.

I could take your instruction to fix a brown face issue by editing all the face related texture files to the same size I think, eliminating the brown face.

But I need to know what is the correct compression, x&y size and ppi I should use for:
- filename.dds
- filename_d.dds
- filename_s.dds
- filename_n.dds
- and any others I am missing.

[₸ʌʟwıcĸ]

That's good to hear I'm glad I could help.

[Panik Goblin]

I'm not allowed to give you a like or favorite because I do not own Skyrim for PC; however, I have to thank you for this guide. you saved me from continuing my headache for the rest of the night..