Color artifacts when changing image format in ImageTool

[Guest misho]

Hello all,I am working on a couple of textures, which are images of building roofs, mostly concrete. I work on them in PhotoShop, and then use ImageTool to convert them to appropriate format. The are all grayscale, and there is no color info. However, when I change format in Imagetool, it does something to them and introduces these blobs with blue and green hues - it drives me crazy!!! Does anyone else encounter this and/or does anyone have a fix for it? Any help would be greatly appreciated!

[Guest misho]

A bit more info on this - please - if anyone can think of anything that might help.I am trying to use a completely grayscale texture (no color info whatsoever) in my scenery, but Imagetool, after the DXT1 conversion, adds slight hues of magenta and green.After some tinkering, I determined that, when converting from a completely desaturated, grayscale 8-bit texture, into a DXT1 format, ImageTool somehow adds color info into the texture. As a result, the texture gets a very slight hues of magenta and green/brown.I tried using an 8-bit grayscale image directly in FS, without DXT1 conversion. It worked, but the colors are still present, albeit to a lesser degree. I can illustrate:http://www.terrabuilder.com/Artifacts.jpgThe image on the left is an 8-bit, indexed, grayscale image. The image on the right is the same image, converted to DXT1 format using Imagetool. The screenshot was taken in the Imagetool, and then the intensities were brought up in PhotoShop... they are exagerated, but i did that for ilustration purposes. These color artifacts appear in FS but to the lesser degree. Does anyone have any idea how to get rid of them and still preserve DXT1 format?Thank you in advance!

[Guest Hans Palsson]

Hi Misho!Perhaps this is not the answer that you are looking for, but saving your original BW-pics as RGB 24-bit BMPs might do the trick? As far as I can tell, only converting the image to any kind of RGB and saving in the said format, and then converting the images to DXT1 does no difference to the resulting image size, compared with original, converted BW images?Your result I guess comes from ImageTool assuming colour imagery "by default", and thus fills the image according to a 256-colour palette. But I might be totaly wrong!/hans

[Guest misho]

>Hi Misho!>>Perhaps this is not the answer that you are looking for, but>saving your original BW-pics as RGB 24-bit BMPs might do the>trick?Thanks Hans - I tried that, same thing happens. I understand your logic behind it, pehaps if I gave it a larger color depth, ImageTool would have easier time with approximation...but no cigars. As far as I can tell, only converting the image to any>kind of RGB and saving in the said format, and then converting>the images to DXT1 does no difference to the resulting image>size, compared with original, converted BW images?>Your result I guess comes from ImageTool assuming colour>imagery "by default", and thus fills the image according to a>256-colour palette. But I might be totaly wrong!Probably something like that. It doesn't matter what the input texture format is, DXT1 always does its thing. Like I mentioned, I managed to have an 8-bit grayscale plain no-mips texture to display as a generic ground texture (not DXT1) and I still had hints of brown in it - from where, I haven't a slightest clue. The size was 66k (no mips) compared to 43k for DXT1, which is not bad I guess.Do you know what are the advantages/uses/applications of DXT1/DXT3/DXT5 formats? Perhaps I should tinker with those to see if they display.

[rhumbaflappy 113]

Hi Misho.You should be able to use 8-bit, mipped, with an alpha channel. That might retain a greyscale for ground textures.Edited:I changed the ground textures from the default Niagara to grayscale; then 8-bit, mipped with alpha... seems to show OK without the colored blotches you found with DXT1.Dick

[Guest misho]

Hi Dick,I was able to re-create the same, except there were still hints of browns in the texture. That would be acceptable, but here is a showstopper: The textures used were not "hard", I couldn't land on them. I guess I'll have to revert back to DXT1.Thanks for the help!

[Guest PaulL01]

Hi Misho,I use many grey scale or unsaturated images for objects with no problem, but I also as a rule stay clear of ImageTool as I have never like the results.Try using Martin Wrights Convim for DXT textures and Elrond FS-Texture Converter for DXT with mips and select nvidia method when using FS-T-Converter.Hope this elps.