If fact, both gradians are done by displaying the same inks... So, it's just a "display" problem and don't have any incidence on your code?
On pictures, linear fail... Really strange.
The problem stems from knowing which INK represents the real 'shade' on real hardware... as it were! If the LINEAR palette is how real looks, then I need to change all my palettes to match, otherwise they're fine.
And it will change the code, as I'll have to move the fade-in INKs to a LINEAR set (0, 1, 2, 3, 4, 5, 6, 7, 9, 8, 11, 10, etc) to look like a proper fade in. Presently it's just 0-26 and then 26-0 to fade out.
My grey-scale images look terrible in LINEAR, yet fine without.
It's strange alright!