Separate Render Channels Gamma settings on a Batch Render

[secondplace]

When rendering separate render channels with a batch script the gamma settings are not applied to the output (tif in this case)
If i render within 3dsmax the gamma is applied to the output images just fine.

I set all the settings with maxscript '-script' argument.
I'm not quite sure how to apply the gamma to the output. here is an example:

OutputPath = "C:\\temp\\File.tif"
MyBitmap = Bitmap renderWidth renderHeight filename:OutputPath gamma:2.2

Now i can set

renderers.current.output_splitfilename = MyBitmap.filename

But it will not use the gamma settings stored in 'MyBitmap'
The '.output_splitbitmap' requires me to 'save' first which does not work in my case since it's a pre-render script.

What am i missing?

[secondplace]

Looks like i found another problem related to 'Separate Render Channels' in a batch.

If a filename is never manually selected as an output it will not save the images if the output is set via maxscript in a batch.
the 'raw image file' works but not the separate channels.

setting it manually must be triggering something that the maxscript does not.
it's an easy workaround but gave me some grey hairs to figure out.