Textrure Editing Tutorial: DXT Compression - Skyrim (Patreon)

To edit a texture you need a program to open ".dds" files. You can either use Photoshop or Gimp, combined with their respective dds plugins.

An alpha texture is a texture with an alpha channel that is not all white; it means it has transparency ingame. (like Hair textures, normalmaps, etc... )

GIMP (free):
https://www.gimp.org/downloads/

PHOTOSHOP:
https://www.adobe.com/sea/products/photoshop/photo-editing.html

Nvidia DDS plugins: (for Skyrim LE):
https://developer.nvidia.com/nvidia-texture-tools-adobe-photoshop

Intel texture works:  (Skyrim SE and Fallout4):
https://www.nexusmods.com/fallout4/mods/49768

All Dxt formats can be seen here, but Skyrim supports only a few:

REMEMBER THAT FACE AND BODY NORMALMAPS (the _msn.dds files) CANNOT BE COMPRESSED in  Skyrim LE (RGB 8.8.8 is the proper format).

• How to save in DXT with Nvidia DDS plugin (LE) :  Always use the " generate mipmaps " option.
   
   

1 - Textueres without alpha --> DXT 1 compression.

2 - Textuers with alpha. --> DXT 5 compression.      [Normalmpas too]

Alpha channel is located here :

3 - Uncompressed no Alpha --> Rgb 8.8.8.

This category includes " Object space normalmaps ", aka the body and face normalmaps (femalehead_msn.dds, etc).

4 - Uncompressed + ALPHA --> (ARGB 8.8.8.8). 

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How to save in DXT with INTEL DDS plugin (SE) :   

• ALL SE textures should be saved this way, however even Legenday edition format works.
  
• "Preset" is a preset users can save locally on their machine. It will keep your saving settings, and it's highly recommended to create a preset for Special edition, since all textures must be saved the same way.
  
• "Texture type" you want "Color + Alpha". ( theoretically you could save non alpha textures as "Color" but it doesnt decrease the file size, so it's not that important.)
  
• "Compression" Must be BC7, FINE quality and LINEAR.
  
• "Mip maps" > Autogenerarte (mipmaps are like LODs, the texturte you see form the distance. They help you not running out of VRAM and avoid the black object bug).
  

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How to save in DXT with GIMP:

DXT1 gimp settings:

DXT5 gimp seettings:

If you want to Import SE or FO4 textures into GIMP you'll have to follow this giude: https://forums.eagle.ru/showthread.php?t=236816

However SE supports DXT1 and DXT5 so you can manage even without.

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Type of textures

A diffuse map is what is commonly called "texture". It defines the color and pattern of a surface.

A normalmap is a bumb map that adds depth and detail to a surfaces, usually converting the mesh's vertex normals into a 2d image.

It regulates how the lights will impact the surface of your model.
The alpha channel  of this map impacts the shine of th surface. White means shiny and black means dull.

Skyrim normalmaps are mostly tangent space normalmaps.
Only the character normalmaps are Object space. 

Read more about T-Space and OBJ-Space normalmaps 

How to create proper normalmaps

Tangent space have ALPHA channel.
The birghter the alpha channel the stronger the shine on your object will be. Pure black means no shine at all.

Object space have "specular maps".
Specular maps are used to define a surface's amount of shine.
They are only used by bodies and faces. They are the same as the alpha channel does for the tangent space normalmaps.

Environment Mapping is an image-based lighting technique for simulating a reflection through a CUBEMAP.
The envmap (usually called "_m." or "_e.") Dictates the intensity of the reflection (white= strong; Black = none).

Envmaps, and specular maps DO NOT SUPPORT color in Skyrim. they are only black and white.

More information on the plug-ins can be found here:
http://wiki.tesnexus.com/index.php/DDS_texture_tools