Tuesday, 15 December 2009

No, I can't enhance that image

My biggest television pet-peeve is "enhance that image", where a forensic investigator or similar person is looking at a blurry image on screen and says to the computer tech "can you enhance that?", so they do, and more detail appears. The problem is that it violates the laws of information.

An image cannot gain resolution after it's taken. If you zoom in and find blurring, you can't undo it. If you blur the image deliberately, the information is lost, or at best damaged. Just once I would like to hear the techie say "What? No, of course I can't 'enhance' that part, or any part. If the image is blurry, it's staying blurry."

Mokalus of Borg

PS - You can, to an extent, guess at part of what is lost.
PPS - But you can never regain what has been properly blurred out.

7 comments:

littlemissrandom said...

I always assumed that the resolution of the image was such that when they zoomed in it was still able to be focussed.

And if not, then the pixels that are 'missing' were interpolated by the software, giving an idea of what the image should be.

John said...

The first scenario is plausible, but in that case it's not "enhance" (which is the word they always seem to use) but "zoom".

In the second scenario, interpolating the "missing" pixels will only get you so far. There are a million different possibilities for pixels blurred together to produce a particular shade. It's like taking four pots of paint, mixing them together to get a uniform brown, then asking someone to tell you what went into it based on sight alone. Could be just about anything.

littlemissrandom said...

You see, you used the word 'plausible', like anything that on TV is meant to be plausible.

John said...

I'm okay with people doing implausible things, if that's the style of the show, but if you're trying to create a serious, realistic crime drama, then you need to stick to some reality. I'd be fine if they just claimed they were zooming in on a very high-resolution surveillance photo, but they don't.

See the tvtropes.org article on the Enhance Button. If you're seeing detail that wasn't there in the original, you're guessing and making it up.

Tim said...

you should check out battlestar galactica. there is an episode where they have a photo they want to enhance and the tech guy tells them he either cant do it, or it will take a day or two for the computer to find enough data to sharpen the image enough to see what it is. also its just an amazing show.

John said...

I think I've seen that episode. Gaeta is trying to see the reflection of a face in a window or something, and the computer spends a day or more "enhancing" the image, after which it turns into a crystal-clear reproduction of Baltar's face. And I groaned. But I do like that show.

Tim said...

yeah, it turns out to be a doctored photo though, so that explains why it becomes so clear. the data was all on the CD it came on, just hidden.