Friday, July 1, 2005

Enlarger PRO improves the quality of your digital enlargements


By David Gewirtz

Some articles are hard to write and some are easier. Sometimes I manage to include veiled polical references. Other times, I get away with including obscure and not-so-obscure references to the various science fiction universes. And sometimes, I have the fun of discussing items of a strange-but-true nature.

This article is one such article. I get to talk about bearded frogs.

Well, technically, I get to talk about one bearded frog, a company called Bearded Frog, located in England. You can tell it's located in England because the manual begins with, "Right, on to the fun bit."

"I get to talk about bearded frogs. Right, on to the fun bit."

Aside from the company's name (which has given me no small amount of joy while writing this article), the bit of fun we're going to talk about is Bearded Frog's Enlarger PRO. We're looking at version 3.0.2.

Enlarger PRO is designed to help you enlarge your digital images and still retain some degree of sharpness. This is not a simple problem and the software necessary requires some very complex algorithms.

The challenge is that when you enlarge a digital image, you need to create pixels where there were none. For example, I enlarged the 768x508 image in Figure A.


Courtesy of our clip art collection, we have a sample needing enlargement. (click for larger image)

When I enlarged the image to four times its original size, the resultant image was 3,072 pixels across by 2,032 pixels down. Where do the new pixels come from? For every one pixel in the original image, there are now four in the enlarged images. That means three out of four pixels need to be created algorithmically, metaphorically generated out of thin air.

Normally, then, you're not going to want to enlarge a digital image. Because the enlarged images are going to consist mostly of interpolated pixels (pixels generated algorithmically based on the values of the original, surrounding pixels), enlarged digital images generally look like crap.

"Enlarged digital images generally look like crap."

However, sometimes you just need to enlarge an image. Most often, this is because you want to make a nice print out of your digital original and your printer prints at much higher resolution than your screen.

To test out Enlarger PRO, we took our test image and enlarged it to 2x and 4x the original size. Figure B shows how the image looks when enlarged to twice its normal size. You'll likely want to click through the thumbnail to see the full-sized enlargement.


Here's the 2x version of the image, using Enlarger PRO. (click for larger image)