🎉 Celebrating 25 Years of GameDev.net! 🎉

Not many can claim 25 years on the Internet! Join us in celebrating this milestone. Learn more about our history, and thank you for being a part of our community!

Back to General and Gameplay Programming

Bitmap compression

GameDev.net · 1999-11-28T22:13:00

Since I have recently suceeded in loading a 24bit bitmap properly, I've noticed something: 24-bit bitmaps are BIG. So, now I am looking for any suggestions for compression, or where I could get a publicly availible algorithm. Winzip has has a 99% compression ration on bitmaps, and I'd like to get that one, but I doubt it's publicly availible. I'll have to go check out the gzip and bzip stuff, they're open source so maybe I'll use one of those. Anyone have any algorithms they've used sucessfully? Anyone know where I can find one for sure? 2meg for a 256x256 bitmap seems a bit high ;-)

General and Gameplay Programming Programming

Started by GameDev.net November 28, 1999 10:13 PM

11 comments, last by GameDev.net 24 years, 7 months ago

foofightr

130

November 27, 1999 11:54 PM

Actually, a 256x256 24-bit BMP file is 192KB, not 2MB

You might think of using PCX files instead, they have built-in compression that usually gives you 25-40% compression. Not as good as WinZip, but hey, it's simple as hell.

The PNG format compresses REALLY well on the images I tested on.

I'm gonna stop talking now, because I don't know all that much about compression and don't want to say something to upset anyone

benjamin bunny

838

November 28, 1999 12:07 AM

Does anybody know where I can get the PNG library?

____________________________________________________________www.elf-stone.com | Automated GL Extension Loading: GLee 5.00 for Win32 and Linux

Anonymous

November 28, 1999 12:32 AM

Hmmm, not 2meg? Musta done my calculation wrong...

Yah.. it is 190k.. oops...

Hehehehe, I said that 2meg was too big ;-)

logistix

122

November 28, 1999 02:45 AM

The PNG spec is at www.w3c.com (or maybe org)

-the logistical one-http://members.bellatlantic.net/~olsongt

Anonymous

November 28, 1999 03:41 AM

sorry if this sounds stupid, but you figure it out by (256*256)*(24/8)=192*(1024)
is that right, I jus guessed, sorry if its a stupid question, its late and Im not think very clear

later

kieren_j

100

November 28, 1999 06:24 AM

PCX files only use their RLE compression (192 cutoff) in 256 colour mode. If you want to compress and dont mind slight quality loss, use truevision targa (TGA) or JPEG.

Anonymous

November 28, 1999 11:51 AM

This is how you'd figure it:

256*256 = 65536 pixels

65536*3=196608 bytes

You take it times 3 since there are 3 bytes per pixel in 24bpp.

Anonymous

November 28, 1999 01:12 PM

That's incorrect. ALL PCX bit modes, 8 bit, 24 bit, etc. use RLE compression.
It doesn't stop at 256 colors. (0-255) is the range of the RGB component,
not the number of colors. And who wants to use JPEG which requires you to
use a whole library of complicated code to decode a single image. It only
takes a couple simple functions to decode a image with PCX.

Speck

Splat

122

November 28, 1999 03:00 PM

Listen, if you don't need compression IN the bitmap (if you are using a global compressor like WinZip to package your resources together) then go with Targa. TGA is basically the easiest format to load (other than RAW files that you know the format of).

- Splat

mhkrause

122

November 28, 1999 03:05 PM

If you're doing 3D with Direct3D, you may want to look into DXTC. It stores the image at 4 bits per texel (at least for DXT1) and hardware support is growing, it's in Nvidia's GeForce 256, S3's Savage4 & Savage2000, 3dfx's upcoming chipset.

🎉 Celebrating 25 Years of GameDev.net! 🎉

Bitmap compression

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

🎉 Celebrating 25 Years of GameDev.net! 🎉

Bitmap compression

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

Reticulating splines