Re: [help-GIFT] 'Re: Ups.

[risc]

wow. i look away for 1 sec, and all this activity. ;)


On Thu, Apr 13, 2006 at 04:45:31PM +0100, David Squire wrote:
> Wolfgang Müller wrote:
> 
> [snip]
> >>It is the GIFT 
> >>feature extraction that *requires* the rescaling to 256x256.
> >>    
> >
> >Yes, I remember the discussion. Many things the GIFT does are due to 
> >decisions that seemed reasonable at the time. 
> Well, the original source of this decision was that the first image 
> collection we used it on was one from Television Suisse Romande, in 
> which all the images were 256x256. Rescaling to this was a hack to allow 
> other images to be indexed with minimal changes to the code.
> >Makes me think of this article you quoted 
> >at the time that was about the lifetime of engineering decisions.
> >
> >  
> Are you thinking of the one ultimately linking the diameter of the Space 
> Shuttle's booster rockets to the width of a horse :)
> 
> 
> BTW, I do think that not rescaling will cause serious problems, since 
> the feature extraction code is premised on 16x16 blocks at the lowest 
> level, and using images of different sizes will result in the same block 
> feature ID being used to refer to different image locations for 
> different images. IDs are assigned simply by counting.
> 
> Regards,
> 
> David

having looked through the code, the real trick is that gift does multiple 
passes at "quarter scale".
the algorithm should work the same for 256x256 (256->16->4->1) as for 1
024x1024 (1024->256->16->4->1).

having said that, i've been working in that direction, but i'm still 
honoring the origional 256x256 resolution. plus, as i said earlier, 
my feature files, and the files gift "works" from in gift_home are 
bitwise identical.

so no david, i havent broken it. just kicking arround ideas. ;)

Julia Longtin <address@hidden>