https://www.posetteforever.com/viewtopic.php?f=68&t=4049&p=45652#p45652
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Nik
Friday, 20 August 2021, 04:01 PM

Huh ??
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So I was house-training a budget work-lamp I'd found on CGT.
https://www.cgtrader.com/3d-models/industrial/other/portable-work-light-3f89fa26-f52b-4a98-a985-79976b11720d

It included a nice 4k texture map for body & LEDs, with a separate material zone for the front glass, to be set almost transparent.

So I loaded the map into free Irfan View, painted all but the LED zone black, re-saved as an ambiance mask.

Looked okay until I dialled up the ambiance to ~99, at which point a patch on top of the case lit. 

Huh ? WTF ?? That's not right...

An exasperated hour of re-mapping and sundry iterations later, I came back to that texture mask and played a hunch. I 'inverted' its colours. Yeah, sorta-diagonal from the LEDs' now-black rectangle, there was a pale grey smudge on the white field. A [b][i]very [/i][/b]pale grey smudge which, before inversion was, to the eye, [b][i]indistinguishable [/i][/b]from black...

Gotcha.

Re-painted, the mask now played nice.

I don't know how that patch slipped through, but lesson learned...