up sizeing for large prints

[gll]

I am wanting to take an image and crop it to panoramic size and have it printed to a 18x48 size , I have done 12x 24s and they look good off an Epson 2200, just wondering how would you increase the size, I'm guessing in small increments step it up. original image is from a D2x 4288x2848 240 dpi. Photoshop cs2
thanks
Gary

[nyphotopro]

The two major resizing software packages are pxlSmartScale (which I use) and Genuine Fractals (which I am upgrading to since pxlSmartScale is not going to be revved for use with CS3.

They are both based on the mathematical science of Mandelbrot Fractal Generation, which is the state of the art.

PxlSmartScale has done an outstanding job for me and Genuine Fractals gets equal raves from many sources.

[jeffkohn]

I've tried a lot of the dedicated tools, and probably the most advanced is SAR Image Processor. The only problem is that it's not exactly a user-friendly application, and some of the routines are very slow.

Honestly, the difference between most modern interpolation routines are fairly small unless you're blowing up an image by some huge factor, or viewing the results at greater than 100%. Most of them do a pretty good job of maintaining sharp edges and avoiding aliasing (jaggies). But none of them can work miracles; you can't squeeze blood out of a stone, and you can't interpolate detail that wasn't in the original capture. If you interpolate an image too much, you'll start to see two things: ringing/halos around edges, and areas that should have fine detail/texture but look too "smooth" because the detail wasn't fully resolved in the original image.

90% of the time the method I use is the one described in in this article. I've found that it works consistently well and is relatively easy and fast to apply.

Another tip I've found useful is to add some grain to the image before printing (I do this before the final downsize in the above method). It sounds counterintuitive, and it doesn't look so hot on screen; but as I said one of the giveaways of an over-interpolated digital image is that smooth, 'plastic' look where there should be texture. Adding some grain can mask the lack of fine detail and give your print a more film-like appearance.

[gll]

Thanks Jeff and Matt
Just now getting back to this and since I'm not one to buy new software I think I will try the Photo shop technique. I noticed he says that he had no luck with this using nikon files above 16x24 ?
thanks
again
Gary

[MicWayWal]

Originally Posted by gll

I think I will try the Photo shop technique.

Since all my work is printed, the photoshop technique is all that I use. I size up my work BEFORE I do any retouching. This way I know how it is going to look before I start and when I finish. I have taken 6mb jpg files of 6.7x10@300dpi to almost 1gb 54x60@300 and not had any issues to speak of. All software that interpolates uses algorithms to work. The later versions of Photoshop CS work very well. No need to buy extra software.

If you are going to print your work, your lab should have software to move it up providing it is the same cropping ratio. But you may not know exactly how your retouching will look.

[adirty1]

I do it all in PS. I up size about 5 to 10 percent each time. It might take a while but I have yet to see any issues. only issues i run into is trying to make to big of a leap from one print size to the next.