Whats better? BMP vs JPG?

[Spudknocker 241]

Hi!  Can anyone explain the differences between using a JPG file verses a BMP file for skins or terrains etc?  I have a feeling that JPGs are better and work smoother but I really don't know

[+russouk2004 6,951]

JPGs far less space and hold a lot of detail...my 2048x2948 jpgs for the mig29,smaller in size and better detail than a 1024x1024 bmp

[+daddyairplanes 8,643]

jpeg takes way less space.

the C-17 i skinned recently originally had a universal bmp for 13 skins(skin in the main aircraft folder with nothing in the skin folders). it took less file space to use jpeg in all 13 folders instead.

Edited October 1, 2015 by daddyairplanes

[Gatling20 748]

JPGs take up a lot less space on your hard drive than BMPs, and I also think they load faster in the sim than BMPs.

[Spudknocker 241]

Ah ok thanks guys that's confirming my suspicion!  I tried converting an entire terrain to JPG's and it works remarkably well my frame rate skyrocketed!  I would totally recommend this! 

[+Gunrunner 313]

Let's see, a typical 1024x1024 BMP is always 3MB, the JPG version with the lowest compression (100% quality) is around 600-700kB, the DDS version with MIP images is around 650-750kB.

 

The more complex the skin is, the heavier the JPG will be (conversely, a 1024x1024 skin consisting only of pixels of a single colour would be around 20kB), BMP and DDS however always have the same file size for the same spatial dimensions.

 

BMP is frankly the worst format, it takes more space on disk and it takes longer to load (because nowadays it's faster to decompress a JPG/DDS than read a BMP, this hasn't always been the case).

JPG is a nice intermediary, it takes the least space and it's fast to load, however it requires a bit more processing to load than DDS and takes up more VRAM than DDS (NB: with Kerbal Space Program, I'm not sure it holds true for Strike Fighters 2, I'll have to check).

DDS are the best, they take only marginally more space than JPG in typical situations, they load the fastest and use the least amount of VRAM (see the NB above).

 

 

P.S. : "Lossless" JPG produced by some graphic software as well as the one included as stock by ThirdWire may actually be larger than DDS in many cases.

 

P.P.S. : Take into account that DDS is an accepted format only for skins, your best bet for mass conversion is JPG (and even then, there are a few instances where only BMP are read, demonstrating how "sub-optimal" some parts of the code are).

Edited October 1, 2015 by Gunrunner

[+Gunrunner 313]

One thing I forgot to mention, there is a HUGE difference between JPG and BMP.

 

You can put BMP at a plane or ship root directory and they'll be used unless there is a file with the same name inside a skin directory, the same thing does not work with JPG.

 

Let's say I have a plane with 2 image files constituting a skin, it has 2 skins, but those skin only differ on the second skin file.

 

With BMP I can set things up as follow :

 

Aircraft\Plane\Skin_1.bmp

Aircraft\Plane\Skin1\Skin_2.bmp

Aircraft\Plane\Skin2\Skin_2.bmp

 

And it will work, but if you want to do the same thing with JPG you have to do :

 

Aircraft\Plane\Skin1\Skin_1.jpg

Aircraft\Plane\Skin1\Skin_2.jpg

Aircraft\Plane\Skin2\Skin_1.jpg

Aircraft\Plane\Skin2\Skin_2.jpg

 

So depending on the number of skins and the commonality between them, it might make a huge size difference (because one 3MB BMP file is smaller than 12 600kB JPG files).

 

It also means that converting BMP in place might end up with broken textures.

 

 

Keep in mind though that you can mix and match file types, making :

 

Aircraft\Plane\Skin_1.bmp

Aircraft\Plane\Skin1\Skin_2.jpg

Aircraft\Plane\Skin2\Skin_2.jpg

 

possible and probably most efficient in cases of a large number of skins with high commonality.

Edited October 3, 2015 by Gunrunner

[+daddyairplanes 8,643]

Thats been referred to as universal skin Gunrunner. But depending on texture size it may still be smaller overall to use jpeg in skin (shocking when its the case even with 15 skin folders!)

[Blade 274]

You can put BMP at a plane or ship root directory and they'll be used unless there is a file with the same name inside a skin directory, the same thing does not work with JPG.

 

It depends on what format the lod calls for. If it calls for jpg files, then you can put jpg files in the plane root folder.

[+WhiteBoySamurai 1,092]

BMP is frankly the worst format, it takes more space on disk and it takes longer to load (because nowadays it's faster to decompress a JPG/DDS than read a BMP, this hasn't always been the case).

 

Would it be possible to get some data to back that up, please? I've been under the impression that the time/processing power to decompress a JPG negated any advantage of smaller file size.

 

 

I've experimented with DDS textures for smaller ground objects before, using DXT1 compression, but I'm wondering if there are more optimal settings for this sim. What's the best compression scheme to mimimize loss of quality?

 

Also, is there any advantage to using a non-compressed DDS compared to a BMP? Should I generate mipmaps, or does the game auto-generate them?

[+1977Frenchie 1,037]

Besides changing the BMP to JPG files in the terrain/map folder, do you have to tell that somewhere? Like changing a log from image.bmp to image.jpg so it will load out.

 

Does the same apply to the objects?

[+russouk2004 6,951]

This skin for example at 2048x2048...JPG=2mb,BMP=12mb....go figure....lol

Edited October 7, 2015 by russouk2004