Wednesday, February 04, 2009

How to cheat a crop

Part of the art of restoration is to generate data when it isn't there but you know it ought to be. A lot of historic images have damage at the edges. This one is a glass plate negative, which was a popular technology from the mid-nineteenth through early twentieth centuries. Glass colloidon plates were an improvement over daguerrotypes because getting a negative makes it possible to create high quality reproductions; daguerrotypes couldn't do that. The trouble was glass plates are very fragile. They tended to collect scratches and often the emulsion would simply peel away. That's what happened at the top of the photograph here.

It's tempting to just crop that damage out of frame; someone even tried that. Here's their result.

This gets rid of the damage, but it leaves the portrait with an odd composition. The subject's head wasn't intended to be so close to the top of the frame. That gives it an oppressive feel, and so much of the tree in the background is lost by the crop that the leaves no longer stretch continuously from right to left across the image. That loss enhances a compositional flaw in the original: a branch appears to be growing out of her head. The more context is present in terms of how much of that tree appears in the background, the less distracting that branch will appear. Ideally I'd like to grab the camera, take two paces to the left and reshoot. But I don't own a time machine and this photo is about a hundred years old.

The next best solution is to cheat. Yes, cheat. I cropped the image a little bit higher than the actual remaining data allowed, then patched in a small blank area at extreme upper right.

Cheating isn't something to try recklessly, of course. Here it was reasonably certain that the only missing data were a few leaves. There's no unique historical value to those leaves and it was already clear from the unrestored image that a higher crop had been the original artistic intent. I wasn't going to be so bold as to cheat data all the way to the very top of the original crop, but a small careful cheat improved the composition.

The key to cheating a crop is to do it only on small areas that are obvious to intuit and where no essential data is likely to have existed: blue skies, dirt, or in this case tree leaves.

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