Celestia Forums

hello

my problem is : i read somewhere that dss files are smaller so, more portable etc...

i have the photoshop plugin to save a file in dss format but the results are way bigger than the original
( ie : i have a 8k night texture , in jpg the size is 3 Mo, and in dss it comes to 21 Mo !!! )

the weird thing, is that there is no slowdowns with the dss but, the jpg kill my machine and is (very very very very)^426 slow .....

any help, explanations, advice, greatly apprecied ;p

thanks, byyyee

I would use the nvdxt.exe file and use this format

c:\nvdxt.exe -file c:\filename.tga -dxt1c

Place both the targa file and nvdxt.exe in the C root directory...

For specular files tga's need to have the specular map loaded into alpha1...save as 32 bit and move to c root...

c:\nvdxt.exe -file c:\filename.tga -dxt5

You can also choose to move the files to any other drive just make sure you specify this when running the script...The script needs to be ran in Start Menu and Run

Another way to do that is using the nVidia plugin for Photoshop / Paint Shop Pro. The final size depends on what setting are you using when you save the texture i.e. Mip maps, DXT mode...

Note: yes, an 8k texture can space up to 20 Meg but loads faster than a jpg's or png's and mantains an acceptable quality ratio.

I am more in line with Rassilon's thinking. I have used the Photoshop plugin with poor results. The alpha chanel gets messed up in the compresion. I would stick to the command line version and you can work with bigger textures and not worry about the additional memory load on photoshop.
Just my 2 cents

thanks very much, , i dl the command line version... will try that....

but why the compressed texture way bigger than the jpg if they re compressed ???

and why a 20 mo dds loads faster and don't slowdown my computer compared to a 3 Mo jpg ????

( only have a geforce since few weeks, just changed my voodoo3, don't know nothing about how works the graphics compressions...)

Because a DDS file can fit into your video card's memory without having to first be decompressed into a bitmap. Other file types must be decompressed before being loaded into memory. eg: that 3MB jpeg gets inflated to a 100MB bitmap that must fit into ram (in your case, swapped heavily between system and video memory causing a real slowdown)

We are all skipping the main issue here. A jpg is a poor image format and does at times alter the look of your textures and not for the better. The dds format is a convert from the tga format wich keeps most of your visual quality. There in lies the rub. With a jpg you can tweak the file on the fly so to speak a dds is locked. In the end you have to deside which is better for you. I have moved almost excluvsivley to the dds format as Rassilon has.

Oh I forgot to add never use a JPG file when making DDS files...They come out very blocky and pixelated....Use Targa (TGA) uncompressed format exclusively...

Don. Edwards wrote:We are all skipping the main issue here. A jpg is a poor image format and does at times alter the look of your textures and not for the better. The dds format is a convert from the tga format wich keeps most of your visual quality. There in lies the rub. With a jpg you can tweak the file on the fly so to speak a dds is locked. In the end you have to deside which is better for you. I have moved almost excluvsivley to the dds format as Rassilon has.

Attention, unlike tga, png, tiff,... jpg /and/ DXT are both lossy formats. I.e. successive compression and decompression leads to a deteriorated result.

Specifically, after converting a texture from tga -> dxt1c and then dxt1c -> tga on will get a significantly worse texture.


Bye Fridger

Yeah I stopped using them for textures less than 2048 x 1024 because of this....It seems when you make them 1024x512 DDS It looks similar to a JPG saved at somewhere at 70% or less compression...I tend to blur them a bit before a DDS compression then use a sharpen mask to highlight some of the features...This seems to cut back on some of the loss of quality...