Why are vrimg files so big?

[tricky]

I'm rendering some still images, around 4000x4000 pixels. They contain the RGB, the alpha, a couple of multimattes and a couple of render elements. Nothing too fancy.

The vrimg file is well over 1GB.
The extracted 32bit EXR files are no more than 100MB or so in total.

I am guessing this is because the vrimg format has no lossless compression within it. If not, why not?

[vlado]

.vrimg files do not have any compression, so they tend to get large. We will be adding compression for the next V-Ray version.

Best regards,
Vlado

[tricky]

Excellent.