# Thread: Size of an image?

1. ## Size of an image?

Could anyone tell me what is the maximum size of image that opengl can work with? Also I heard that it could only work with images that are in a power of 2? Does this mean that the image will have to be a square? Or can it work with say 1k by 2K?

Thanks

2. ## Re: Size of an image?

If you mean texture images:
glGetIntegerv(GL_MAX_TEXTURE_SIZE, &i);
implementation specific value. Minmum supported resultion must be 64. Power of two is meant for each side separately. Any combination 2^n * 2^m should work if you don't exceed the GL_MAX_TEXTURE_SIZE.
For non-power of two textures have a look for the texture_rectangle extension.

(If you meant screen size look for GL_MAX_VIEWPORT_DIMS.)

[This message has been edited by Relic (edited 12-06-2002).]

3. ## Re: Size of an image?

Relic,

Thanks.

You say resolution must be 64. what does 64 mean?

Originally posted by Relic:
If you mean texture images:
glGetIntegerv(GL_MAX_TEXTURE_SIZE, &i);
implementation specific value. Minmum supported resultion must be 64. Power of two is meant for each side separately. Any combination 2^n * 2^m should work if you don't exceed the GL_MAX_TEXTURE_SIZE.
For non-power of two textures have a look for the texture_rectangle extension.

(If you meant screen size look for GL_MAX_VIEWPORT_DIMS.)

[This message has been edited by Relic (edited 12-06-2002).]

4. ## Re: Size of an image?

the minimum width and height of a texture image is 64. it must be at least 64 X 64 pixels.

5. ## Re: Size of an image?

Originally posted by SThomas:
the minimum width and height of a texture image is 64. it must be at least 64 X 64 pixels.
So many people seem to think this. There is no minimum size for a texture.
What there IS however, is an implementation dependent maximum texture size. OpenGL requires that THIS is at least 64.

6. ## Re: Size of an image?

So ff I code:
int I;
glGetIntegerv(GL_MAX_TEXTURE_SIZE, &I);

'I' should tell me the max integer value that my texture can hold? I have tried this and it gives me the value of 84? Also could anyone give me a briefing on what a texture is? Is it related to my graphics card?

Originally posted by SThomas:
the minimum width and height of a texture image is 64. it must be at least 64 X 64 pixels.

7. ## Re: Size of an image?

Originally posted by Bakery2k:
So many people seem to think this. There is no minimum size for a texture.
What there IS however, is an implementation dependent maximum texture size. OpenGL requires that THIS is at least 64.
of course, how retarded of me. thanks for the correction.

8. ## Re: Size of an image?

Well, 84 is definitely not correct. Probably a typo?

The max_texture_size value is the maximum edge length of a full RGBA texture with all mipmap levels plus borders your OpenGL implementation (driver | graphics card) can handle.

Search for the RedBook.pdf on the web and download it (it's only 8MB). Read chapter 9 for texture mapping.

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