On Sat, 5 Aug 2000, dave wrote:
> I've been using gimp for a short while now, and the one problem that
> keeps
> coming up is when I convert an RGB image to indexed, to save as a gif
> with a transparent background.
>
> I (think I) understand the issues with converting RGB colour to
> indexed, but what I don't understand is that I always seem to lose
> quality too (I guess that's somehow also a colour problem?)
of course you will (though sometimes you can do this and make the picture
look better like a jpeg that really should have been a png)
play with the dithering options, and with how many color you remove. if
you do it right (perhaps with a little touch up just before doing
this) you can get good results with 3-6 bit color on these. the ones where
you can use 4 bit color are usually obvious.
> Even if I do nice simple fonts, in black, on a transparent background,
> I lose quality of the fonts on converting to indexed. I either lose
> nice smooth edges, or pixels within narrow parts of small fonts, or
> both.
>
> Why is this, and is there anything I can do about it? I need to do a
> lot of simple colour fonts with transparent backgrounds, so this is a
> real problem for me.
use the same color as the background of the image when you make the
transperant font, what your losing here is the anti aliasing. you will
still lose the anti aliasing, but it wont be noticiable (or as much).
in a gif, color index 0 is always the one used at transperant.
heres an example of using a 4 bit gif with antialiasing,
http://necrodolly.necroerotic.org/lyrics/dandelion.html
the necrodolly near the top has a black backround, giving it that
"outline" of black (or how it looks "burnt"). the image under that is a
4 bit transperant gif. (which makes it look much smoother than 1 bit
would)
> many thanks
> Dave
>
