PDA

View Full Version : Texture memory- I should know, but I don't



Johnsongraphix
04-19-2006, 01:56 PM
I spent lots of time optimizing images to be used in my scenes. I all about rendering as fast as possible without sacrificing quality. So why are my images (jpegs) at 100-500kb but when viewed in image editor they are 1-5 MB. What is the best way to optimize image maps without loosing quality.

I have searched for a existing thread on this, I thought there should be one, but had no luck.

Lightwolf
04-19-2006, 02:22 PM
All images are decompressed when loaded into memory to be used by LW (or any other program).

As a rule of thumb: width x height (in pixels) x number of colour channels (i.e. rgb, rgba or greyscale) is the amount of bytes an image uses.
LW will also allocate an additional 50% of memory for mip-maps unless you turn those off.
I.e.
1000x1000 pixels, rgb would be:
1000x1000x3 bytes = 3000000 bytes = roughly 3 MB.
including memory for mip-maps: 4.5 MB.

For float/hdr images (32bit per colour channel) you can multiply the number above by 4.

One way to optimize them is to convert them into a paletted, 8bit image in Photoshop and save that as an Amiga IFF. This will restrict you to 256 colours only, but can be sufficient in many cases. You may need to look for the Amiga IFF saver for PS on your CDs, it is not installed by default (I think it is in a goodies folder or something like that).

Cheers,
Mike