[ptx] Enblend Multiresolution Spline Blender

[Pablo d'Angelo]

On Wed, 10 Mar 2004, Andrew C Mihal wrote:

> On Wed, 10 Mar 2004, Pablo d'Angelo wrote:
> 
> > Usually, the overlaps are quite regular (no holes etc.). I think it should
> > be possible to use this method. But probably I missed something, can you
> > explain where you see the problems?
> 
> Ok, here comes the ascii art. Here is the line that enblend currently 
> chooses:
> 
>      +---------------------------------+   /
>      |                                 |/
>      |               +-----------------+---------------------+
>      |               |                /|                     |
>      |               |             /   |                     |
>      |               |          /      |                     |
>      |               |         |       |                     |
>      |               |         |       |                     |
>      |               |        /        |                     |
>      |               |     /           |                     |
>      |               |  /              |                     |
>      |               |/                |                     |
>      +---------------+-----------------+                     |
>                     /|                                       |
>                  /   +---------------------------------------+
> 
> 
> The idea is that the line is equidistant from the zones where there is 
> only one image providing data.

Ok, now I see! Thanks for your patience with me ;) Actually, this
translation probably looks better too, since the seaming line doesn't
the change direction into a horizontal line.

> > What would you prefer?
> > I can to do the conversion to vigra, but it'll take a few days.
> 
> I don't know vigra at all.

I think vigra is nice, because of the very complete template approach
to image data types, it can be confusing with all that c++ template stuff
sometime. I just want to make sure that its easily possible to blend other
(for example hdri float) image formats as well.

> I see that it has a distance transform function 
> though, and that could be used to caluclate either of the two types of 
> lines above. What's important is the algorithm it uses.

While I haven't looked at the algo in detail, it mainly seems to do two
loops over the whole image. should be pretty fast.

> I want to do some more math and get a better understanding of what is 
> going on at the boundaries of the images in the laplacian pyramids, and 
> what is happening to the pixels that are in the blend zone but not in the 
> intersection of the two images.

Ok. I'll start to write a faster mask creation algorithm and integrate that
into nona.

ciao
  Pablo