Is Resampling or "Ressing Up" OK?
Ressing Up?
While there is no free lunch, it is possible to create extra resolution when needed, but within certain limits. If you're a Photoshop user, you've most likely noticed "Resample" button in the "Image Size" dialog box. If you check this box it decouples the locked relationship between Width and Height and Resolution and allows you to set the resolution independent of the height and width. Resampling is scary as it almost always results in detail and clarity loss. Done in moderation, this technique can allow you to make prints larger than your original image would normally allow. The reason for this is that a large print is viewed from a greater distance than is a small one and therefore the effect is masked. As I said, the key word is moderation.
Note: If you are merely trying to make a low-rez web image into a beautiful high rez image, you're asking for the impossible. Photoshop can not create detail that doesn't already exist - all it can do it divide you already low resolution file into more or less pixels.
Ressing Down?
Finally, you would also use this to res-down an image. If you're preparing a photograph for use on the web you want to have it at 72 ppi, you would turn on Resample Image, set the value to 72 ppi, and then set the width and height to whatever you needed. Photoshop will then throw away the unneeded pixels to create an appropriately-sized file.
Sometimes you just have to Resample.
It would be great if all of our photos and continuous tone images came to us in a digital file fitted to the exact size and resolution that we need, but it's simply not going to happen. Fact is, we use so much existing and ordered digital media, that we have to resample it at least one time to just get it the size we need. Keep in mind that scaling, resizing, rotating and skewing an image on screen forces the image to be resampled as well. Doing too many of these things to a single image can cause an image to look fuzzy as well as become desaturated. The key is to resample as few times as possible! My suggestion would be to plan your artwork ahead of time on paper, rather using your digital files to experiment with. And as always, Keep your original artwork back-ed up in a safe place in case you need to go back and grab that first-generation, clean image.
