[Scummvm-devel] FreeSCI options and filters

[Max Horn]

Am 03.09.2009 um 14:38 schrieb yotam barnoy:

> On Thu, Sep 3, 2009 at 2:09 PM, Lars Skovlund <lskovlun at image.dk>  
> wrote:
>
> It may be worthwhile to point out that there are a few situations
> where graphical glitches result from the non-dithered mode. These are
> situations where a view (foreground sprites - bitmaps which we can't
> un-dither by definition) uses the same dithering pattern as the pic
> (background picture) around it, either for "blending in" or for
> special effects. Not dithering the background makes this look slightly
> ugly. That's one more reason for having dithering as an option.
>
>
> That would  explain the dithering on the buttons in Filippos'  
> "after" image from QFG I.
>
> Couldn't we find a way to un-dither after all? We know the palette  
> that's desired for the image, and we know how it dithers, so all  
> that remains is scanning the bitmaps for the (up to) 16 patterns and  
> replacing them with the proper palette colors. If that's too  
> expensive, we can maybe add in hints per image.

It's easy to construct examples where this would not work correctly,  
no matter how you do it. A simple example: Consider a triangular area  
(or any area with non-horizontal or non-vertical borders), framed with  
a black border, filled with a black-white checkboard pattern. At  
border, the dithering pattern and the enclosing frame mesh up, and in  
general it becomes difficult to impossible to properly separate the  
pattern from the frame. In this simple example, a human could  
potentially do it (and maybe one can even make a clever algorithm).  
But increasingly harder cases can be constructed.

But maybe this is not an issue for SCI, maybe only very easy cases  
occur?

Bye,
Max