Texture question for painters

[Mick]

I think I know the answer to this but I'm guessing, so I hope someone knows the answer for sure.

It's about DXT textures. Like anyone who paints models, I learned many years ago that DXT textures are very lossy, and every time you open, edit and change one, it becomes corrupted, more and more so every time it's saved. So for many years I have worked on textures in 32-bit format and released them that way.

What I'm scratching my head about is whether DXT textures get corrupted when opened and closed by FS. I suspect not; I suspect that FS simply opens, reads, displays and closes the textures without saving them. If I'm right, they should continue to look right no matter how many times the model they cover is loaded in FS. Does anyone know for sure about that, one way or the other?

Due to the vast difference in file size, to upload limits, and to a plethora of skins painted for an upcoming release, I am leaning towards using DXT3 format for textures. I suspect and hope that it won't make any difference, but I can't help feeling a bit anxious about it.

I'll ve very grateful is someone can ease my mind, or warn me off a potential mistake.

 

[Mike71]

.................................I think I know the answer to this but I'm guessing, so I hope someone knows the answer for sure.
What I'm scratching my head about is whether DXT textures get corrupted when opened and closed by FS. I suspect not; I suspect that FS simply opens, reads, displays and closes the textures without saving them. If I'm right, they should continue to look right no matter how many times the model they cover is loaded in FS. Does anyone know for sure about that, one way or the other?

Due to the vast difference in file size, to upload limits, and to a plethora of skins painted for an upcoming release, I am leaning towards using DXT3 format for textures. .............................

As I understand it, every time you edit a bmp file directly it loses some quality. However, if you do it through DXTbmp or say Photoshop and reload/save it, it won't. Are you using DXTbmp for editing?

 

[Motormouse]

Hi

They (DXT) don't degrade by being read by fs, and if anything , load quicker in sim... or at least they did with the systems that were state of the art when fs2004 was released.. its all to do with the number of bits/ bytes they use in memory. With today's systems and multi gigabyte hard drives for graphics and storage, this load time is less of an issue.

As you know, DXT3 is a texture compression format.

When sampled for compression, a texture is sampled in groups of 4 pixels,
within that group 2 pixels are sampled to give the resulting colour swatch for the 4 pixel group. Which is why every time you edit a DXT texture, it progressively degrades.

With older, and hence simpler lower initial resolution texture files,( eg 600 x 600) then compression loss becomes a problem, but if you're working something like 1024 x 1024 then it becomes less of an issue.

What does show up compression loss, is mipmaps, now, some systems ( graphics card and driver combination) work better with mipmaps, and some without, there's no telling which.

Ttfn

Pete

 

[Mick]

As I understand it, every time you edit a bmp file directly it loses some quality. However, if you do it through DXTbmp or say Photoshop and reload/save it, it won't. Are you using DXTbmp for editing?

Thanks for your reply.

Yes, I use DXTbmp. I don't know of any other software that will allow work on DXT files, or produce 32-bit textures.

You can open and edit a 256-color, 24-bit or 32-bit texture file as much as you want and they will not deteriorate. The trouble is, every time you edit a texture in DXTbmp and save it in one of the DXT formats, there is considerable corruption. Silver colors take on a green cast, colors change, and not the same everywhere on the image, so there are wide jagged discolored edges next to any slanted or curved color demarcation lines. As far as I know, this lossiness is an integral characteristic of DXT textures and can not be avoided no matter what software is used. The problem isn't with the DXTbmp program, because it doesn't cause 256 color or 32-bit textures to deteriorate like that- only the DXT formats. So the problem is in the format.

What I'm wondering is whether the images get opened when the texture is displayed by FS and saved when it's closed, or simply opened and then closed without being saved - which I think is the case - I just wish I knew for sure. And I think someone has give me the answer in the next post below yours.

 

[Mick]

Hi
They (DXT) don't degrade by being read by fs, and if anything , load quicker in sim... or at least they did with the systems that were state of the art when fs2004 was released.. its all to do with the number of bits/ bytes they use in memory. With today's systems and multi gigabyte hard drives for graphics and storage, this load time is less of an issue.
As you know, DXT3 is a texture compression format.
When sampled for compression, a texture is sampled in groups of 4 pixels,
within that group 2 pixels are sampled to give the resulting colour swatch for the 4 pixel group. Which is why every time you edit a DXT texture, it progressively degrades.
With older, and hence simpler lower initial resolution texture files,( eg 600 x 600) then compression loss becomes a problem, but if you're working something like 1024 x 1024 then it becomes less of an issue.
What does show up compression loss, is mipmaps, now, some systems ( graphics card and driver combination) work better with mipmaps, and some without, there's no telling which.
Ttfn
Pete

Thanks Pete,

That's about what I thought, but I was guessing. I saw no reason to think FS would "save" an image file after displaying it, but with Microsoft products you just never know. Well, I didn't know. I'm glad you do! Your comments include far more detail than I ever knew, so thanks for the education!

Ah yes, mipmaps! From the very beginning of FS9 I've saved without mips, and I've had to open many, many skins on models and repaints that I've downloaded and re-save them without mips. That being a graphics card thing makes sense, because I know that mips haven't driven some folks to distraction like they did me on my rig. Otherwise they would never have released their work with mips! I understand how mipmaps reduce processor load by not showing a texture in more detail that should be visible from the distance it's seen from in the sim, but apparently different systems are very different in how far away something should be for a lower resloution map to be displayed. Before I started eliminating mips I would see solid black AI planes come in to land and taxi in, almost reaching the parking ramp before their colors and markings suddenly popped into visibility. I know that not everyone had that aggravation! I think today's computers no longer need the resource conservation that mips were intended to be.

But my question was about DXT and your answer has taken a load off my mind. As you might guess, the reason I'm considering DXT textures is that I've gone completely overboard painting skins for an upcoming project and if I leave the textures in 32-bit format the zip file will be too big for SOH's upload limit and I'd have to break the aircraft up into a two part assembly kit. Not that there's anything wrong with that, but I'd rather keep things simple.

 

[gaucho_59]

The way around it I use..

I do my work in layers, etc. in PSP 2021 now.... but ever since early PSP... I save that texture.
Then I fuse all layers, and save as an extended bmp... or bmp... whichever the original was in.
then, if I need to add, modify, enhance or whatever... I take the finished last version from the
texture folder to be replaced with my new hopefully better production.... (in my archive)
work on it.. in layers, etc.... after all modifications, I fuse it, covert it with the DXTBMP program
and replace the one still in texture folder... this way there is no degradation whatsoever...

G.

 

[Mick]

I do my work in layers, etc. in PSP 2021 now.... but ever since early PSP... I save that texture.
Then I fuse all layers, and save as an extended bmp... or bmp... whichever the original was in.
then, if I need to add, modify, enhance or whatever... I take the finished last version from the
texture folder to be replaced with my new hopefully better production.... (in my archive)
work on it.. in layers, etc.... after all modifications, I fuse it, covert it with the DXTBMP program
and replace the one still in texture folder... this way there is no degradation whatsoever...
G.

Thanks for your reply. You're absolutely right.

That's what I planned, for the same reason. It's a sure thing that once I converted the textures to DXT I would find errors that needed correction, or I would find photos of yet another plane with interesting colors or markings that I would feel compelled to paint, using an existing skin as a starting point. So I intend to keep a set of 32-bit external textures from each skin, just in case.

It has occurred to me that I could offer the set of 32-bit external texturesto anyone who wants them, if by themselves, without the internal common textures and the models, panels and sounds, they might come in below the upload limits. Maybe. It's a big "if." I'm afraid I really went overboard on this project, and it's not even close to completion yet. But it might just be the best thing David and I have done yet. (As it should be - we all should keep getting better with practice.)

 

[Ascua]

Hi Mick and Gaucho

Yep, that is more or less the way I work myself. My trick is to create the texture in in layers in PhotoShop and save it in *.psd format in a folder in the Texture folder. The trick is that DXTbmp can read psd format directly and reduce it to a single layer in the process but will not modify the original PSD file, so I do not need to flatten or fuse it (maybe DXTbmp can read PSP as well?) and therefore the PhotoShop files are always unaffected.
Then use DXTbmp to add the Alpha layer stored in another folder and just save it in the desired format, DXT5+alpha for me (FSX, sorry, but the same procedure works for DXT3).
When modifications are needed just modify the layers in the PSD file, save it (in PSD format) and create the new version of the texture with DXTbmp.
That way your PDS files are always safe, do not loss any detail and are ready for modification.
Once I am satisfied, all the components (textures in PSD format) and Alpha (textures in BMP format) get saved somewhere else and left only the DDS files in the texture folder, the resulting size is nowhere close to the limit for uploading.
You can use the stored files to create new textures whenever you want and all the common layers will be ready and waiting.

Just for information I have never seen degradation of textures in FS2002, FS9 or FSX

Hope it helps

 

[Mick]

Hi Mick and Gaucho

Yep, that is more or less the way I work myself. My trick is to create the texture in in layers in PhotoShop and save it in *.psd format in a folder in the Texture folder. The trick is that DXTbmp can read psd format directly and reduce it to a single layer in the process but will not modify the original PSD file, so I do not need to flatten or fuse it (maybe DXTbmp can read PSP as well?) and therefore the PhotoShop files are always unaffected.
Then use DXTbmp to add the Alpha layer stored in another folder and just save it in the desired format, DXT5+alpha for me (FSX, sorry, but the same procedure works for DXT3).
When modifications are needed just modify the layers in the PSD file, save it (in PSD format) and create the new version of the texture with DXTbmp.
That way your PDS files are always safe, do not loss any detail and are ready for modification.
Once I am satisfied, all the components (textures in PSD format) and Alpha (textures in BMP format) get saved somewhere else and left only the DDS files in the texture folder, the resulting size is nowhere close to the limit for uploading.
You can use the stored files to create new textures whenever you want and all the common layers will be ready and waiting.
Just for information I have never seen degradation of textures in FS2002, FS9 or FSX
Hope it helps

Thanks!

I don't have Photoshop, but I do a sort of layering as I paint textures. I'll start with a base texture for all skins, including things like panel lines and other details, then a layer with common markings like national insignia that can be pasted onto the base texture for most skins, then the individual markings for each skin. I use MS Paint for very simple things and PSP7 for most more complex things. Very occasionally I'll use Sierra Snapshot Express for certain things that it does very easily.

One of the disadvantages of being so compulsive about painting models is that I almost never get to fly one. So I couldn't just check a model that wears DXT textures that I fly often, to see if the skins have deteriorated, because there aren't any planes that I've flown often enough to see any degradation with use. Not even the ones I've worked on with David. It annoys some me that I never get to fly, but whenever I get some hobby time I find that I always have a paint job I'd rather work on instead. What I need is a thirty hour day and a nine day week. Then I might have time for everything I want to do.

 

[Mick]

Test results to share

OK, I converted a texture file from 32-bit to DXT3. I did no editing, I only saved the file that one time.

When I checked it out I found significant corruption. In the scrap view I've circled some of the corrupted sections in green.

Apparently it's just not possible to retain fine detail in DXT files.

Bah!

I guess the scrap view is too small to see much, but if you look close you can see what I mean.