Re: [GD-DEVEL] trasparent image width antialiasing

On 2/1/07, yagyog <[email protected]> wrote:
> ----- Original Message -----
> From: "Pierre" <[email protected]>
> To: "yagyog" <[email protected]>
> Cc: <[email protected]>
> Sent: Thursday, February 01, 2007 12:35 PM
> Subject: Re: [GD-DEVEL] trasparent image width antialiasing
>
>
> > Hi,
> >
> > On 1/30/07, yagyog <[email protected]> wrote:
> >> ----- Original Message -----
> >> From: "Pierre" <[email protected]>
> >> To: "yagyog" <[email protected]>
> >> Cc: <[email protected]>
> >> Sent: Tuesday, January 30, 2007 3:48 PM
> >> Subject: Re: [GD-DEVEL] trasparent image width antialiasing
> >>
> >>
> >> > On 1/30/07, yagyog <[email protected]> wrote:
> >> >> I have a problem, Excused but I do not speak English
> >> >>
> >> >>
> >> >> I have in input one image png with antialising
> >> >> with uniform solid background
> >> >>
> >> >> I would want
> >> >>
> >> >> 1) to eliminate the background
> >> >> 2) recreate the channel alpha in order not to lose the antialising on
> >> >> the
> >> >> text
> >> >>
> >> >> It is possible?
> >> >> you can give me of the information ?
> >> >>
> >> >> I try this code but not work:
> >> >>
> >> >> //
> >> >> //load a, load b  and create test
> >> >> //
> >> >> a = myLoadPng("a.png");
> >> >> b = myLoadPng("b.png");
> >> >
> >> > Can you give us a link to the images a.png and b.png please?
> >> >
> >> > --Pierre
> >> >
> >> Yes
> >> the color is changed but ,
> >> it does not change nothing
> >>
> >> http://www.yag.altervista.org/varius/a.png
> >> http://www.yag.altervista.org/varius/b.png
> >> my result
> >> http://www.yag.altervista.org/varius/test.png
> >
> > You have to use the alpha component in your image. So the blending
> > will be done when you copy a or b over test
>
> >. But if the original  images do not contain any alpha components
> Exact! :(
>
> , the anti aliasing being
> > done against a given color (green and yellow in your case), you will
> > have a visible aliasing.
> >
> Excuse I have not understood well
> you could makes to understand me better. even with of the code

There is no way to achieve what you want without using the alpha
component in your images.

Here is an example image: http://blog.thepimp.net/misc/test_text_aa_alpha.png

Load it in gimp/gqview, you will see the alpha values in the edges.

--Pierre