For anyone wondering what TXF files are and how to use them: Briefly, TXF files define how the transparency/opacity of your textures is handled.

If you've poked around in the "Activemod" folder (inside the "Mod" folder) or installed a texture mod downloaded from somebody else, you may have noticed most texture mods include a cryptic text file ending in ".txf" (short for "Texture Formatting".)  These are simply text files that define how the transparency (or lack there of) of a texture is handled.

Textures come in three types: Solid ("Opaque"), solid with holes in it ("AlphaMask", like the eye holes in a "Mask"), or translucent ("AlphaBlend"... pixels that blend with underlying pixels to create a "see-through" effect.) When you create a texture in your favorite graphics software, you give all or part of your texture solid, sheer or transparent pixels. For example, a wall would probably be completely solid. A fishnet stocking texture has holes in it where the legs show through. A peek-a-boo nighty might be "see through" but not invisible.  TXF files can NOT make a solid texture sheer or transparent, but they CAN turn a sheer or transparent texture opaque if set incorrectly. All values are in Red/Green/Blue/Alpha* format. Alpha is optional based on your image. Instead of "RGB", you can use "L" for grayscale textures.

Create a text file and enter the appropriate information (only a single line of text) and save it with the same name as the texture it belongs to using the ".txf" extension.

Here are the different options:

"RGB_888" "Opaque" -> For solid textures in color. "8" means "8bits" per channel. 24 bit color is 256 shades of Red, 256 shades of Green, and 256 shades of Blue. No "A" or fourth value because opaque textures have no Alpha/Index channel.

"L_8" "Opaque" -> Same thing but for grayscale textures. Only one "8" because 256 (2 to the power of 8) shades of gray requires only 8 bits. Using "L" with a color texture has no noticeable effect.

"RGBA_8881" "AlphaMask" -> For color textures with holes in it. Note the added "A" & 4th value. Think of how an actual mask has eye holes in it. Alpha values > 1 for AlphaMask are interpreted as "1". "8888" would be read the same as "8881". A masking bit is either on or off.

"LA_81" "AlphaMask" -> Same thing but for grayscale textures with holes in it.

"RGBA_8888" "AlphaBlend" -> The keyword "AlphaBlend" tells TK17 your texture contains semi-transparent (sheer) pixels. An Alpha Channel of "8" supports 256 levels of transparency.

"LA_87" "AlphaBlend" - Grayscale with 256 levels of gray & 128 levels of transparency.

(Interesting oddity: "LA_88" and "LA_44"... be it AlphaBlend or AlphaMask... will crank the Green channel to Max, turning your texture bright green... both color & grayscale textures. I have no idea why. Doesn't matter if the texture is in color or grayscale. Only occurs with those two values.)

Optional: The "/WriteZ" Modifier -> Added after "AlphaMask" or "AlphaBlend". The WriteZ option modifies the way pixel collisions are handled. There's no general rule when to use it. You should try the texture mod without WriteZ first, then add it and compare the result to see which looks best. Mostly for dress/top/bra/necklace textures, it's a good idea to test the textures on long-haired models where the hair might lie over other them. "WriteZ" is good for giving necklaces (for example) priority over solid clothing so you can see them. Or used with sheer clothing textures so you can see the necklace through them (examples: "LA_81" "AlphaMask/WriteZ" or "RGBA_8888" "AlphaBlend/WriteZ".)

These options provide full alpha transparency support. Unfortunately, this may also create rendering artifacts when object collision occurs (note: most graphics hardware processes alphamask faster than alphablend, so don't use "AlphaBlend" unless you really need semi-transparent areas.) Leaving out the "A" (alpha) value when applied to textures with transparent or sheer pixels will turn those pixels solid/opaque.

None of the prefix settings (other than the above mentioned "oddity") should have any impact on the appearance of your texture(s) since that is controlled almost entirely by the texture itself. It's primary function is to control both transparency & memory consumption. Using "L" instead of "RGB" with grayscale textures reportedly uses less memory (unconfirmed.)

If you are trying to conserve memory by using textures with fewer colors, adjust your txf file appropriately.

Variations:

"L_8" "Add" - Rare. Assigned to a grayscale image that is used to add a "glow" effect to all three channels of the underlying texture. Black does not do anything, gray adds medium brightness and white is for maximum brightness. However, TK17 must already be looking for this secondary texture to use it.

"RGBA_4444" "AlphaBlend" -> 16bit (8^4 for 4096) colors + 16 (2^4) levels of transparency.

"RGBA_5551" "AlphaMask" -> 16bit (8^5 for 32768) colors plus 1bit for mask (pixel is either on or off.)

"RGB_565" "Opaque" -> A solid texture with 40 shades of red & blue but, 48 shades of green.

"LA_84" "AlphaBlend" -> Best for reduced B&W textures in 256 shades of gray and 16 levels of transparency.

"LA_41" "AlphaMask" -> Reduced grayscale images in 16 shades of gray & only 1bit required for masking.