Digital BW, The Print

Clayton
 
The program I mentioned a short while ago was Photozoom Pro 
(formerly S-Spline Pro) from Benvista.  There was a long discussion 
of interpolation methods some time ago and S-Spline technology is 
the latest "maths".  I am traveliing at the moment and don't have 
access to the original thread postings which I saved on my 
computer.  If you are interested I can chase these up when I return 
to London.  I have purchased Photozoom. It's not cheap at Euro129.  
I have not used it extensively so far but it has worked extremely 
well when I have used it.  I have a few stability issues with the 
Mac Photoshop export plugin (CS2) but no issues with the standalone 
application.  I am working though these issues with the folks at 
Benvista who have been extremely helpful.
 
Incidentally I did ask them the following question and their 
response is copied below:
 
>is there any merit in stepping a spline interpolation in increments 
rather than in one hit?


"
We recommend doing it in one hit. Technically, using multiple 
increments -also called "stair" interpolation- is mathematically the 
same as 
doing it in one step and taking a slightly larger area into account 
around 
each pixel when interpolating. Theoretically this could result in 
small 
improvements (although not necessarily, and can also result in more 
ringing/jaggies), however it also introduces rounding errors because 
you 
always get small "mistakes" when interpolating, and by interpolating 
many times these mistakes will naturally occur more often and stack 
up.

Actually, we thought about adding stair interpolation to PhotoZoom a 
while ago, but after some experimenting we didn't consider it a real 
improvement (there was practically no visual difference) and the 
much 
longer processing time definitely wasn't worth it.
"