Light absorption test - Is it possible using Gimp?

[marco-gimp]

Ah yes; the dreaded drifting off topic.

It was an organic process - my post was open for a number of hours, as information was gathered, and the concept took shape.

I paused at the end of it, wondering whether I should post it all.
Then, having checked the views, I figured that there were enough people interested in the topic ... so I posted.

I agree with you that there is still some knowledge acquisition required, to firm up or deny assumptions; but this isn't for immediate completion.

Re the heads up on the 'axing' ... thanks for that.
All the work is backed up, so if it happens, nothing is lost.

Thanks for your interest and explanations