DXTC On GeForceFX Cards

[StealthHawk]

Back when the gf4 was originally released, we heard from some sites like Tom's Hardware (http://www6.tomshardware.com/graphic/20020206/geforce4-17.html) that DXTC support was fixed on nvidia cards. However, people in the forums posted shots from Quake3 which showed that the dithering in the sky with DXTC enabled was not as bad as it was with a gf3 card, but it still paled in comparison to the image quality of the sky with DXTC off. Now, this discussion was back before the forums were wiped, so I'm not sure how many people remember it.

Anyone with a GeForceFX card, please investigate this issue! Look at the Quake3 sky with texture compression off, then enable texture compression and see if the sky looks the same. Please post screenshots of before/after.

I am very interested in finding out if this issue was ever really fixed or not, it seems like everyone else forgot about it :(

[Kruno]

Also the DXTC issue in Quake 3 never occured on a Linux based OS. Is that still the case?

[DSC]

The DXT1 issue that affects GF256/GF2/GF3/GF4 should be tested on the FX cards. I'm also interested to see if this is fixed or not.

[Tsunami]

Normal texture compression has alot of quality loss but DXTC is a compression file that obviously compresses but doesn't have the loss of quality that normal compression has (is this correct although i know what DXTC is i never really compared the difference)







P.S
i'm getting a geforce fx 5900 ultra tuesday i'll let you know :eek: :angel: :afro2:

[Deathlike2]

Quick parody to Chicken Little:

FanATIcs: The sky is blurry! The sky is blurry!

Hmm.. I wonder though too..

[DSC]

Bump.

No one has any info on this? :o

[The Baron]

I will try it tomorrow.

[Typedef Enum]

My gut feeling tells me that nVidia made about as many changes to DXTC as they did to the Antialiasing technology...In short, it's the same. Just a feeling, as I don't have an Fx board to test.

[Lfctony]

I don't think they've fixed anything. This is on a GFFX 5800 with the 44.03 drivers set on Quality. No AF/AA.

This is WITHOUT Texture Compression
http://groups.yahoo.com/group/lfctony/files/shot0000.jpg

This is WITH Texture Compression
http://groups.yahoo.com/group/lfctony/files/shot0001b.jpg

This is also WITH Texture Compression
http://groups.yahoo.com/group/lfctony/files/shot0000b.jpg


:(

[StealthHawk]

I think those screenshots resemble the gf4's. That was a long time ago, so maybe it is better...but it still obviously decreases quality :(

Anyway, thanks for taking the time to do the comparison and post the screenshots :thumbsup: We'll see what other people turn up too, it will probably corroborate what you've shown.

[Kruno]

I think those screenshots resemble the gf4's.

Well that NV3x's IQ looks exactly like the NV2x lines. ;)

[StealthHawk]

Originally posted by K.I.L.E.R
Well that NV3x's IQ looks exactly like the NV2x lines. ;)

No, that DXTC quality was supposedly fixed on the gf4 over the gf3, when in actuality it wasn't. Although gf4 did look better than gf3 when using DXT1.

The problem was, of course, that Tom took a screenshot of Quake3 with DXTC enabled with both a gf3 and gf4. The gf4 screenshot looked better, and he pronounced it fixed. What he didn't do was compare the DXTC shot to the non-DXTC shot for a point of reference :p Well, I don't think Tom wrote the review, but whoever did.

[Lfctony]

Added another pickie in my above post.

[Nutty]

I dont understand what you guys are expecting? Turning on DXT compresson _will_ result in a drop of quality, regardless of implementation.

IIRC, wasn't the bug more to do with the alpha formats of DXT? DXT1 has 1 bit alpha, DXT3 has uncompressed alpha, and DXT5 has compressed alpha.

DXT5 looks the best with alpha gradients, as more info can be stored in the compressed 4bits, than uncompressed 4bits.

[Kruno]

Originally posted by Nutty
I dont understand what you guys are expecting? Turning on DXT compresson _will_ result in a drop of quality, regardless of implementation.

IIRC, wasn't the bug more to do with the alpha formats of DXT? DXT1 has 1 bit alpha, DXT3 has uncompressed alpha, and DXT5 has compressed alpha.

DXT5 looks the best with alpha gradients, as more info can be stored in the compressed 4bits, than uncompressed 4bits.

You are right, though look at Quake3 qith DXT1 TC enabled in Linux and you will see it looks much better than it does in Windows 9x/NT.

On the last set of message boards there was a massive thread about it.

[Hanners]

Originally posted by Nutty
I dont understand what you guys are expecting? Turning on DXT compresson _will_ result in a drop of quality, regardless of implementation.

I think you're right - Maybe we need someone with an ATi board to post the same screenshots with DXTC enabled and disabled, then compare them to the GeForceFX screenshots.

[deejaya]

Originally posted by K.I.L.E.R
You are right, though look at Quake3 qith DXT1 TC enabled in Linux and you will see it looks much better than it does in Windows 9x/NT.

On the last set of message boards there was a massive thread about it.

Maybe I'm seeing things, but all my Linux games look better than their Win counterparts. I have a GF3 so I think from reading this topic my DXTC is just broken anyway.

[gstanford]

That screenshot probably isn't the best to judge DXTC compression quality on.

I suggest you use NOLF2 instead, specifically "the death of Cate Archer" cut scene (early in the game - use maphole cheat to skip quickly thru to it). Focus on the ninja's face.

I've attached a jpeg (irfanview quality 85) of how my GF3 renders her.

edit: changed the jpeg to a closeup png because you can't really tell from the jpeg

She looks much better (but not perfect on GF4's I've seen running).

[StealthHawk]

Originally posted by Hanners
I think you're right - Maybe we need someone with an ATi board to post the same screenshots with DXTC enabled and disabled, then compare them to the GeForceFX screenshots.

From what I remember Radeon cards rendered the sky perfectly with DXTC on.

[saturnotaku]

Originally posted by StealthHawk
From what I remember Radeon cards rendered the sky perfectly with DXTC on.

Yes they do. I can post a pic if you like.

[Kruno]

Originally posted by StealthHawk
From what I remember Radeon cards rendered the sky perfectly with DXTC on.

That's the problem.

[Nutty]

I have a demo, that shows an image under non-compressed, DXT1, DXT3, and DXT5

download it from

http://opengl.nutty.org/extensions/index.html

Its the 2nd one down. If someone has an ATI card, and could screenshot it in non-compressed, and DXT modes, that would be cool.

requires DevIL image library too;
http://opengl.nutty.org/OpenIL/index.html

BTW, you press space bar to cycles modes, on my Gf3 at work, I can easily see a degradation from non-compressed to dxt.

[Nutty]

Thanks to Stealth, heres some shots taken on an ATI r9500 Pro.

http://opengl.nutty.org/dxt/ATI/DXTComparisonATI.html

You can clearly see a degradation in skin tone when compression is on.

And the comparison page here

http://opengl.nutty.org/dxt/NV/DXTComparisonNV.html

[gstanford]

Just goes to show that DXT1 should not be used on any but the lowest quality and least used textures. It quality is crappy.

DXT3 and DXT5 are the preferred formats. The issue with the Quake sky was that Id used DXT1 when they should have used DXT3.

Can any GF_FX owners and GF4 owners send Nutty some comparison shots?

[Nutty]

I can do some GF4 shots when I get home.