Texture Improvement Guide
I don't have the talent to create and draw my own textures and I am an amateur when it comes to existing texture improvement and upscaling, but I've learned a lot from my own experience and from advice of more knowledgeable TW3 graphics modders, such as BoostIn4Kix (huge thanks for that!). I use Adobe Photoshop and I don't know if everything in GIMP functions the same way.
0. 16bit color and gradient banding
I always start working or switch from using 8bit to sing 16bit color as the first step and switch back to 8bit color only before saving files in TGA format simply because TGA format requires 8bit color. TW3 can import PNG files, which can be saved in 16bit color, but importing such files usually results in wcc_lite errors. Here is why I start with 16bit color:
a. It allows working with higher bit depth per channel, which results in better color accuracy
b. It makes it easier to apply certain effects, such as blurring seams
c. It allows for creation of smoother, higher quality gradients and although they cannot be saved in 8bit format, at least Photoshop, converts smooth 16bit gradients into 8bit gradients with high quality dithering that is not applied if the texture gradient was created/edited in 8bit. This is an excellent way to get rid of as much gradient banding as possible. Again, huge thanks to BoostIn4Kix for this awesome tip.
1. DDS Texture "de-compression" for grayscale-only textures
As I posted in my Texture Compression Guide, most textures in TW3 use the old DTX5 DDS compression method that creates heavy noise and blockiness in red and blue channels, but leaves alpha channel in-tact, and only adds mild noise in green channel, which control luminance in diffuse textures. One of end-results of such compression is color noise for textures meant to be black & white / grey. Here are my steps and tips:
a. Assess texture pattern differences between alpha channel and RGB channels to decide whether alpha channel, the one with least compression noise, can serve as a replacement for RGB channels. Such is the case for many particle textures, where alpha channel is almost identical to RGB channel patterns, or can be made so with only mild adjustments.
b. If alpha channel is not identical to RGB channel, but very close, you can simply use Adjustments or some other tools to try to make it 1:1 (but the compression noise would not be there)
c. If alpha channel can't be used at all, simply copy green channel onto red and blue channels, which results in a higher quality grayscale texture with less compression noise in general and 0 color-noise
d. If the texture is only partially grey, depending how much of it is grey, it can be useful to use lasso tool or whichever method to copy/paste only those grey parts of the texture from green on red and blue channels. There is probably a Photoshop script that can automatically do it for you and if someone knows where to get it or can make one - it would be appreciated.
2. Seamless and tileable upscaling
Many textures in TW3 and other games are seamless or tileable. For those who don't know what that is, Googling states "A seamless texture is an image that can be placed side-by-side with itself without creating a noticeable boundary between two copies of the image". When such textures are upscaled, downscaled, or when blurring, sharpening, de-noising and other filters are applied to such textures, they stop being seamless and that can often be visible in the game with random lines appearing, disturbing/disrupting the pattern. There are several ways to fix that and one way (that I know of), the best way, to prevent the loss of seamlessness when upscaling, downscaling, and applying other filters. Here are my tips, tricks, and some steps:
a. Seamlessness can be verified via Photoshop's Offset function, where you would specify half the size/pixels of the image's width and height to detect the seam.
b. To compensate for an already-created seam, you can can manually apply blur to the seam or other tools, like healing patch tool. However, it is not ideal and those blurred lines can still be detected
c. You can also use the "Fill" function in Photoshop with "Content Awareness" enabled, but that can create even more visible lines, which can be blurred to make the final result both seamless and prevent the obvious blur line from showing up, but again, it is far from ideal.
d. The best method is the method that prevents creation of such seams in the first place. Once again, BoostIn4Kix was kind enough to help me (us) out with this. To prevent creation of seams (in textures that do not have it to begin-with), you need to
- increase the size of canvas by 200% horizontally and vertically, leaving the texture in the very middle.
- Copy and paste the texture onto itself
- Use the move tool and move the pasted texture next to the original one (seamlessly). Photoshop will snap-it-in for you.
- Rpeat this process to have this identical texture above, below, to the left, and to the right of the original textures, all snapped-in
- Flatten the image (important step or it won't work).
- Perform whichever action that would usually result in loss of seamlessness (upscale, downscale, blur de-noise, etc.)
- Select the original texture (now in the very center) and crop it to have your seamless texture without any blurred lines or pattern disrupted by the Fill function
3. To be Continued (I hope)...
Special TW3-only notes:
- Before importing and cooking your textures, please read my Texture Compression Guide to make the most informed decision.
- For some textures, like cloud textures, you can find identical ones with less compression noise in DLC (or other) directories to improve vanilla non-DLC textures. BOB DLC clouds are an excellent example. With a few manipulations and use of better compression method (or by not compressing at all), I was able to create my Beautiful Sky mod mostly through copy/paste of different channels from BOB clouds to vanilla clouds, then upscaling, and a bit of cleaning. I was able to achieve the same for some smoke subuv and fire subuv textures.
More tips and/or corrections to my guide are very welcome if you are mature about it.