11-19-2022, 01:08 PM
(11-19-2022, 09:42 AM)rich2005 Wrote: As far as I know transparency in an indexed image, is on or off as previously stated and not possible to edit from the Gimp indexed colormap. You can get a simulation of semi-transparency using dithering but only when the image is originally RGB mode -> Indexed
This a simplified image with two of the bands with semi-transprency from RGB mode.
The indexed image:
Hi, thanks, dithering is not really an option for the map overlay thing that I'm creating - I guess I'll manage somehow to convert the original indexed thing to RGB, using the same image converted to grayscale, adjusting the curve, so it's going mainly from 60 to 90%. Somehow combining the layers with multiply to get the transparency of wanted value. When I save that as PNG, it will be 24 bit and about 3 times the size of the original (as it was when I did something similar some years ago), but it will have the transparency I need. And I guess it was about what I did back then.
If there's some other method that doesn't blow up the size by a factor of three, it would be fine, but seems to be difficult or next to impossible.