OK! rich2005's screenshot exposed what the problem was;
In the dialogue for converting to Indexed colour mode, I noticed a checkbox for the first time - "Remove unused colours", which is checked by default. In rich's screenshot, it's unchecked.
If this is checked, I noticed when converting to indexed mode, the order of the colours is changed, due to the removal algorithm of course (even though it never ended up removing anything). Ofnuts, this is the "extra CPU" that would be required!
That is the point where the colours are being randomised! Not on export like I thought.
Leaving this unchecked, the palette order is maintained during conversion. Whew!!!
Now I can stay within GIMP
Thanks guys!
In the dialogue for converting to Indexed colour mode, I noticed a checkbox for the first time - "Remove unused colours", which is checked by default. In rich's screenshot, it's unchecked.
If this is checked, I noticed when converting to indexed mode, the order of the colours is changed, due to the removal algorithm of course (even though it never ended up removing anything). Ofnuts, this is the "extra CPU" that would be required!
That is the point where the colours are being randomised! Not on export like I thought.
Leaving this unchecked, the palette order is maintained during conversion. Whew!!!
Now I can stay within GIMP
Thanks guys!