[idas]

I need render to resolution 1600x1200, then...

1600*1200 = 1920000

MXI constant is: 112

MXI filesize in MB:
(1920000*112)/1000000 = 215 MB

Its true ?

You can try it !

[tom]

i don't think so...

let me explain how raw data is stored in memory for resolution 1600 x 1200

for 1 bitplane, each 1 pixel is represented by 1 bit...
so in one scanline there are x/8 bytes means 1600/8=200 bytes
for 1200 scanlines there are y*scanline bytes of data for each bitplane 1200*200=240000 bytes
since the resolution is 24 bit for [R8,G8,B8], all bitplanes cost 240000*24=5760000 bytes (5.49 MB)

The above calculation is for raw 24 bit image data.
MXI is not a 24 bit image data.
It's a more precise spectral data and not stored as bitplanes.
MXI is derived to bitmap for viewer.
The constant you found (112) should be giving you a hint about it's precision about each pixel

..and 215 MB is 215*1024*1024=225443840 bytes.
therefore your constant must be 117 something

[idas]

ok, can you then explain to me, why with my example can i know how big MXI file will be stored on disk ?

[Mihai]

i guess because mxi always stores the same amount of info regardless if it's "used" or not. Guess they haven't done any compression/optimisation scheme on it yet.

I mean if 70% of your mxi is pure black, or white, no need to store any additional info for them, you can't extract info from them. Well....I'm making big assumptions here...