On Mon, 22 Oct 2007 22:49:42 GMT, "SS" wrote:

I have seen that Genuine Fractals and Photozoom seem to be 'intelligent'
software but have also seen a review that puts the fred Miranda 'stair
interpolation' Photoshop action better than these. I wonder what
experiences/advice the subscribers to this newsgroup can give. Is there
anything even better on the market now.

Thanks


Any of the methods that are using PhotoShop's native bicubic interpolation and
its 16-bit math foundation (like Miranda's stair interpolation or that
Richardson-Lucy iteration) will be abysmal compared to other more evolved
interpolation methods. PhotoShop is still only using 16-bit math (think Windows
3.1), it has to throw away so much data required for the detail. If you are
using 16-bit images you're already at the limit of PhotoShop's math-bandwidth.
Trying to do anything complex with 16-bit data in a 16-bit math environment is
pushing it beyond what it was designed for and inherently limited to. No
different than trying to add 5+7 and getting 2 or 9 as a result in a
single-digit math universe. The 10's unit of measure would have to be thrown
away in that environment because it doesn't and can't exist within that
constraint. The same as getting ERR- displayed on your hand calculator when
trying to multiply values beyond what it can calculate.

I happen to use the old S-Spline 2.2 first to see if that will do the job. When
just trying to find a page for that I see now that it's long since been updated
into PhotoZoom. It's worked so well all these years, I guess it's time to try an
update.

CleanerZoomer is also a pretty interesting utility to keep on hand. It's a
multi-purpose tool that includes a Lanczos upsampling. Its noise removal method
I also sometimes like better than others I've used.

http://www.stratopoint.com/czoomer.htm

There used to be a site online that compared all the various upsampling
utilities. I have long since lost that bookmark. Maybe you or someone else can
find and share it again. It's where I was lead to these other programs. So much
will depend on the kind of detail in your image and which kinds of detail that
you want to enlarge. Some of them work better if there is a lot of sharp angular
details in your image. For example if your image is of a graphics-arts event, it
would upsample all those bold edges, signs with text, and color detail very
well. Other interpolation programs work worse on those but do better on softer
or more curved and random details. This is why that comparison page was so
handy. It clearly showed when one utility and method was better than another.
There's no one-size-fits-all solution when it comes to upsampling.