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Image Compression

Started by Pav3 Aug 14, 2001 at 6:41 PM 0 replies 800+ views

Original Post

Aug 14, 2001 at 6:41 PM

Hello, my name is Pav and I need a little help. Iv''e begun learning OpenGL in order to program a 3D game,(Adventure RPG) now i''m having a problem with Textures... It seems that Ogl would only load BMP''s... they take up a lot of space... I wanted to know a few things... 1.How Can I compress an image to s3tc format and load it to Visual C++? (I have ATi Radeon, it supports and has extentions for this format GL_EXT_texture_compression_s3tc i think.) 2.Same for DXT1-5. 3.Iv''e read a lot about the Wavelet method to compress images, but i only found an explenation of the wavelet method itself, without regard to compression, can someone help about that? 4.Although I prefer to use my own image format, if i will not be able to compress it with wavelet or something else, im gonna have to use a jpg compression, how can i decompress it and load it? Thank you! (i''m building quite a large game, so i cannot use bmp images, i don''t have that many GBytes!!!

) **> ATi Rules! nvidia doesn''''t...that simple! <**

gmcbay

Aug 14, 2001 at 7:30 PM

OpenGL doesn''t load any images. That''s up to your app.

DevIL (formerly OpenIL) is a great image library for texture loading. It mimicks the OpenGL API so it should be very familiar to use. You can download it at:

http://www.imagelib.org

There''s a bunch of patent issues related to wavelet compression that could cause you to wind up paying fees (or lawyer costs if sued) when using wavelet techniques. However, if you''re really interested in the technical aspects, "Introduction to Data Compression" by Khalid Seyood has a good section on wavelets.

Using your own image format is usually not that great of an idea unless you invent some wild new format. Why not make use of the work of experts in the field and use proven image formats? The time & effort you save can be used elsewhere.

Lastly, the best source of information on dealing with compressed textures (with hardware support) is OpenGL is NVidia''s developer site. I realize from your sig that you might not like visiting their site, but you should.

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