Software for increasing image resolution

[KristianJ]

I'm Googling to find out how I can up the size of a few photos I took last Saturday night at my girlfriend's sister's engagement party. The pics turned out great through my good ol' S5500, but I realised that I'd not changed my resolution from 640 x 480 (which I'd used to take pics of the moon and use my digital zoom). I want to print them out on 6 x 4, but I'm not sure if they'll turn out any good. So I was wondering what techniques, software, etc. everyone here uses for increasing image sizes without losing quality.

I'm looking at a site that mentions a couple of processes in Photoshop such as bicubic, plus a Photoshop plugin called Genuine Fractals (which I think I have as part of a PC magazine CD I got a year or so ago.) Are these any good? Thanks in advance for any replies

 

[Jer]

For all of them there will be image quality lost, there is no way to properly keep it the same quality while blowing it up. I don't know too much about the ways of keeping this loss to a minimum though. It might be worth it to get one shot printed and see if it's ok for a 6x4?

 

[Southern Cross]

The programs interpolate the dead space between the active pixels and "fill them in". At that resolution, you might be able to eek out a 4X6. Genuine Fractuals would be your best bet. Don't expect any miracles, though.

 

[KristianJ]

I tried the bicubic method last night and printed out a 6x4 (I have no need for anything larger)...the quality was reasonable enough for the photo, so I'm probably going to stick with that. I couldn't get Genuine Fractals (Version 2 LE I found out that it was) to work properly after I installed it, so I'll keep on tinkering with it some time later on.

 

[klf]

I guess that's the reverse of anti-aliasing?

 

[KristianJ]

I don't even really know what anti-aliasing is...

In any case, as I said above the bicubic provided satisfactory results, but I'll have to remember not to have the camera on the 640x480 setting again. I only did in the first place because I was trying to get a nice optical + digital zoomed in pic of the moon (I did get a pretty good one after a couple of attempts) and plain forgot to change it back to my maximum resolution. Otherwise it's always at the regular 4MP resolution setting.

 

[Orchids]

This is anti-aliasing...

The one on the right is anti-aliased, to smooth out the pixels.