Re: [vassalengine-devel] [vassalengine] What happened to the image quality in 3.0?

[Joel U. <uck...@no...>]

Thus spake Joel Uckelman:
> Thus spake "b5mith":
> > Hey guys.
> > 
> > I fixed this problem years ago because zoom-out was unusable.
> > Zooming is now much quicker in 3.0 but it has come at the cost of
> > image quality.  A lot of the minis players depend on the quality at
> > different zoom levels being consistent;  I was just wondering if this
> > will be fixed shortly?  I would rather have slow (before caching)
> > zooming with good quality than fast with low quality.
> > 
> > Ben
> 
> Between 2.9 and 3.0 I started targetting parts of VASSAL which are too
> slow, zooming among them. All of the tests I did at the time indicated
> that Java's built-in scaling, as of Java 1.5, produced scaled images of
> quality comparable to your area averaging filter, at many times the
> speed, and so we switched to that in 3.0.0. Some people noticed the
> speed increase and were happy. I was perplexed when we started to get
> complaints about the image quality, since I hadn't seen much difference
> between the two. It turns out that bilinear scaling is very close to
> area averaging on some images and less so on others. All of the images
> I tested were ones where bilinear scaling does well, while some popular
> modules (e.g., Combat Commander. Thanks to Tim McCaron for providing
> some images so I could see the difference.) contain images where bilinear
> scaling does poorly.
> 
> Once I knew what the problem was, I relaized that the only way to get
> high-quality scaling at an acceptable speed was to break up images 
> into tiles (here I'm speaking of map images, not tokens) and scale only
> the tiles which are on-screen. So, from the begining of August I set
> about implementing a tiling scaler. In the process, I implemented a
> Lanczos filter, which is both faster *and* produces better quality
> output than area averaging. All of this is in a working demo now.
> What's left is to integrate the parts from the demo into VASSAL.
> I don't know how long that will take, though it's what I'm working
> on presently.
> 
> So, here are the options as I see them:
> 
> 1. Go back to using area averaging for now. This will make people who
> like faster zoom unhappy, but appease people who use modules which need
> high-quality scaling.
> 
> 2. Wait for me to finish integrating the new tiling scaler. This is less
> work for me, but I can't estimate how long it will take. It won't be done
> today, done in a week or a month, maybe.
> 
> 3. Switch to the Lanczos scaler, without tiling, for now. This is some
> work, but I think it's something I could do today.

I tried #3, which was easier than I expected. There's a modified JAR here:

  http://www.nomic.net/~uckelman/tmp/vassal/Vengine.jar 

Ben, please try this and let me know your opinion. (Anyone else who wants
to is also welcome, of course.)

-- 
J.