Video Enhancement (You can't display what you can't see)
O.K. - forget I used the phrase "video ehancement" in the title. The proper (correct) phrase is "video clarification", but, thanks to all the "pop, quasi-realistic, CSI-Miami, CSI-Las Vegas, CSI-Ad Nauseum garbage" on television I figured you'd recognize the term "Enhancement" since that's the misnomer these fact-challenged programs lead you to believe companies (and underfunded police agencies) are capable of doing. (We'll discuss the sub-par "acting" of David Caruso at a later date).
For the next few "blogisodes" I'm turning over the site to my able bodied wing nut right hand man and audio/video engineer extraordinare Eric Graf (who works with me at Video Resources, Inc. in the Video/Audio Forensics lab) to explain as simply as possible the why's and wherefore's of video and audio clarification and why it's important for you to know what will and, more importantly, what will not work for you.
Here's Eric's Video Clarification Blog: (Enjoy!)
The following is a list of random factoids about video. Hopefully there will be pearls of wisdom herein that will help us better serve you when you get some of that all-important footage that needs enhancing (oops! I mean clarification).. Warning: I tend to overuse parentheses (but I’m trying to improve).
First of all, you know those TV shows like CSI where they take grainy, blurry, little bitty digital video and enhance it until you can read the serial number on the bad guy’s cellphone as he throws it across the pitch-black parking lot?
Guess what ?. . . That’s fake. (GASP!) (Take a few moments to catch your breath and then continue reading once your vision returns to normal.. I know - it's a shock.)
Those shows are no more a reflection of real CSI science than James Bond is. The writers who come up with stuff like that just need some convenient way for the good guys to crack the case, so they make up something silly that they think most viewers will buy. And most viewers do. Please don’t be one of them.
Video doesn’t work like that. We wish it did.
RESOLUTION - THE CRUX OF THE PROBLEM (well, one of the many problem cruxes)
OK - Here's the basic formula for understanding how video images are displayed on your TV screen/monitor: Standard definition video has very specific limits in resolution: 720 pixels wide by 486 pixels high. Well, actually, it’s more like 243 pixels high in practice, but that’s getting on a technical tangent, so let’s not go there. Anyway, that’s much lower than even the most inexpensive analog still camera.
What that means is, once something in the frame gets smaller than a certain number of pixels, then that’s it. PERIOD. You aren’t going to be able to see what it is. The best supercomputer in the world can’t take a solid block of color (which is what a pixel is) and figure out what details within the block made the block come out the solid color it did.
That’s the main reason most of the CSI TV stuff is bogus. It ignores the resolution issue. We can certainly take a video picture and make things on it bigger. But they won’t be sharper, or easier to see or read, because video resolution "is what it is".
Bigger will just mean blurrier, and if you get too big, you won’t even be able to tell what you’re looking at anymore. Things that are too small just can’t be sharpened or enhanced from a video source.
You know MORE that the writers at CSI!
COPIES AND WHY WE HATE 'EM
Analog video degrades every time you copy it.... A lot. Often enough so that whatever we’re supposed to be seeing can’t be seen anymore. (Digital Video, when copied correctly, doesn't degrade at all.)
Now, we all know that most VHS-based surveillance equipment is poorly maintained and the tapes are reused until they get holes worn in the tape. It can often be difficult to get the fool things to play back properly.
Here’s the deal: Here at VR, we’re GOOD at getting the fool things to play back properly. In fact, we have a warehouse full of equipment to do just that. I can’t tell you how many times we’ve received tapes that wouldn’t play in any VCR in the building except for ONE. (There’s this one beat up old Philips deck that I’ve rescued from imminent dumpsterization three times here at VR, and now guard with my life. It’s ugly, dirty, a little sticky, and not of much general use, but it does an amazing job with certain multiplex timelapse tapes.)
In extreme cases, we’ve been known to go inside one of our decks and deliberately misadjust it to match a particularly screwy tape.
But if you give us a copy, then we’re stuck with whatever happened playback-wise when the copy was made. Did the copyist forget to set the tracking? Was there a problem with the signal level going from one machine to another? Did they run it at the wrong speed and accidentally cut off 2/3 of the content? We’ve seen all these things, and we can’t fix them if they’re “burned in” (ie, recorded) into the copy. And even if they did get everything exactly right, it’s still a copy, with degraded quality.
And oh yes, on the topic of multiplexed tapes . . . you know, the ones that record lots of full-screen cameras really fast so that they show in a jumbled flicker? Please don’t have anyone demultiplex them for us. Reread the part on “copies” and you’ll see why.
What’s that? You say you’re going to copy your tape onto a DVD? Just as bad, I’m afraid. Possibly even worse!
Catch my next post and I'll tell you why........
