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Re: Possible to use JPG textures?
[Re: Matt_Aufderheide]
#111951
02/16/07 03:10
02/16/07 03:10
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Joined: Sep 2002
Posts: 1,381
New Brunswick, Canada
Ayrus
Serious User
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Serious User
Joined: Sep 2002
Posts: 1,381
New Brunswick, Canada
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Also, on top of that, jpegs are very easy to use to hide other files. Basically, I can embed an exe into a jpeg, and whenever the jpeg is accessed/opened, it runs the exe locally. Not so easy to do with other image types and it is quite a security hole really.
Regards,
Ayrus
suprised my account is still active....
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Re: Possible to use JPG textures?
[Re: Ayrus]
#111952
02/16/07 04:05
02/16/07 04:05
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Joined: Mar 2006
Posts: 2,503
SC, United States
xXxGuitar511
Expert
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Expert
Joined: Mar 2006
Posts: 2,503
SC, United States
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what is this about hiding programs in JPG's??? I'd like to know this information... For security reasons (*cough*)...
xXxGuitar511
- Programmer
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Re: Possible to use JPG textures?
[Re: xXxGuitar511]
#111953
02/16/07 05:50
02/16/07 05:50
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Joined: Sep 2002
Posts: 1,381
New Brunswick, Canada
Ayrus
Serious User
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Serious User
Joined: Sep 2002
Posts: 1,381
New Brunswick, Canada
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Lol.. I wont say how it is done, but I can tell you it takes only a minute to do, you can actually use winrar to see the files that are hidden in the jpeg, and it is a very common launch method for keyloggers nowadays, Especially on world of warcraft websites (curse-gaming.com for an example).
Regards,
Ayrus
suprised my account is still active....
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Re: Possible to use JPG textures?
[Re: Ayrus]
#111954
02/16/07 15:15
02/16/07 15:15
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Joined: Dec 2003
Posts: 1,225
germany
gri
Serious User
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Serious User
Joined: Dec 2003
Posts: 1,225
germany
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Quote:
Also, on top of that, jpegs are very easy to use to hide other files. Basically, I can embed an exe into a jpeg, and whenever the jpeg is accessed/opened, it runs the exe locally. Not so easy to do with other image types and it is quite a security hole really.
Regards,
Ayrus
no no no,
if you dont have the "extrk.exe" file (installed by an email attachment prog) then there is nothing to fear.
JPEG files are not dangerous.
Only then your system is already infected there are capabilities to abuse JPEG's.
,gri
"Make a great game or kill it early" (Bruce Shelley, Ensemble Studios)
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Re: Possible to use JPG textures?
[Re: Paragon]
#111955
02/16/07 21:25
02/16/07 21:25
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Joined: Aug 2002
Posts: 681
Massachusetts, USA
Ichiro
User
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User
Joined: Aug 2002
Posts: 681
Massachusetts, USA
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 I'm using ATI's Compressinator, without much luck -- I seem to get major artifacting. In the above image, I took the original (left, 3.0MB), then saved as JPEG (center, 0.2MB). I then took the original and saved as DDS DXT5 (right, 1.0MB). The on-disk savings wasn't as much as I'd hoped (though the in-memory savings is nice), and I'm getting artifacts up the wazoo. Am I missing something? As a sidenote, we were playing around with something that allowed us to use JPEGs and alpha transparencies (essentially one JPEG for RGB, and a second greyscale JPEG for the alpha). It worked pretty well, but of course, only saved disk space; not video memory.
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Re: Possible to use JPG textures?
[Re: Ichiro]
#111956
02/17/07 08:07
02/17/07 08:07
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Joined: Jul 2001
Posts: 6,904
HeelX
Senior Expert
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Senior Expert
Joined: Jul 2001
Posts: 6,904
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Quote:
I'm using ATI's Compressinator, without much luck -- I seem to get major artifacting.
"DXT1C/DXT1A.
Compression ratio: 8:1.
The DXT1A is often described as "RGB texture with one-bit-depth alpha". Actually, for each pixel there are two available configurations: if the alpha channel is set to 1 (white), RGB channels store usual color info. Instead if the alpha channel is set to 0 (black), upon saving the texture RGB channel are set to 0 as well. In other words, each pixel could contain color info only if the alpha channel is set to white. This makes a sense, as a black alpha channel usually means that the pixel is completely transparent (invisible), so there's no need to store color info. This algorithm is tipically used for icons, decals, blood, tatoos, i.e. texture with a completely transparent part.
Instead, DXT1C is often described as "RGB texture withouth alpha channel". This is not true: the alpha channel is still present, but is completely white. Actually, there's no physical distinction between this and DXT1A, simply upon choosing DXT1C as compression algorithm the alpha channel is set to be completely white just before saving. This is tipically used for common completely opaque textures.
(...)
DXT5
Compression ratio: 4:1.
This is often described as "RGB texture with interpolated alpha". The application field is the same of DXT3, theoretically this should be chosen if alpha channel is featuring slow gradients. Again, from my personal experience this algorithm is better than DXT3 in most cases, so I recommend using DXT5 when a comparison is not available.
Notice that DXT1 compression ratio is double than DXT3,DXT5, and so it generates half size dds files. The three algorithms are different only for the alpha channel compression, the RGB part is exactly the same for all three. So if you don't need alpha blending you should use DXT1, as using DXT3 or DXT5 will only double dds file size without any improvement in visual quality. Instead, I regularly find out in texture replacement lots of DXT5 compressed textures with the default white alpha channel.
The most common mistake is this: some developers probably think that DXT5 is increasing RGB visual quality, so they systematically use it without caring whether alpha channel is used or not. (...)"
(source)
Have a good one,
Christian
Last edited by HeelX; 02/17/07 08:07.
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