Just What is a Digit Anyway?
By J. Allen Leinberger
I have always tried to avoid “techie” talk and computer jargon in these columns. You don’t need it and I’m not quite sure that I understand it. But as the TVs make their switch and so many other things are being sold as “digital,” I figured that it’s about time we plodded our way through it together.
Let’s start with the old, out- of-date, twentieth century term “analog.” Basically this is a vibration. If you’re old enough to remember records and turntables, you may recall the record needle. The wavy grooves of the record passed underneath the needle and made it vibrate. The other end of the needle passed through a magnetic field in the cartridge and that, in turn, created an electronic vibration, which got amplified and sent to the speakers, which in turn vibrated the air and gave us sound.
“Digital” is a computer term. If you have basic computer training of any kind, you may know about binary code. Binary is simple a switch that is either on or off. In computer language that would be a zero or a one. Each zero or one is called a byte. Like atoms creating molecules, a number of bytes make up a bit. Bits, for some reason, are put together in sets which are multiples of eight. Thus you will hear terms like 32 bit or 64 bit. Think of those as computer “molecules.”
Just like molecules combine to make compounds the bits combine to make anything from sight to sound. What amounts to a computer inside of your iPod or HD TV or digital camera converts these into the same sound or picture that you would expect in your old record player or TV or film camera.
The big difference is the old vibration can get jumbled and confused. When that happens, you get static or hum or some other kind of distortion. The digital signal keeps its integrity. The bit remains the same coming out as going in. Thus the sound or picture is much truer and sharper.
In your old TV, as you may know, the little ray gun in back shot out a series of lines that ran back and forth like a farmer plowing his field. In analog TV there are about 500 such lines. Digital TV has 1080 lines. (This is why the number 1080 is used so much in digital TV ads.)
In fact these lines are now made up of digital pixels that are nothing more than the tiny dots that make up a picture. It’s pretty much the same in your camera. Cameras are sold based on the number of pixels in the thousands. These are megapixels. Thus a camera may be a 5 MP (megapixel) or a 10 MP. Popular handheld cameras now are available with as much as 16 megapixel capacity. Your cell phone by now may be up to 3 or even 4 megapixels.
For reference, here at the Journal, I have been using a Canon PowerShot S 40, which we reviewed a few years ago. It is a 4 MP camera whose pictures print quite nicely. Can you imagine what 16 MP will look like? (Stay tuned, Canon is sending out a 10 MP for us to review soon.)
If this thing with the dots is still confusing you, let me refer you to the neoimpressionist painter Georges-Pierre Seurat whose most famous work is “Sunday Afternoon on the Island of La Grande Jatte.”
You’ve seen this picture before. It is made up of colored dots, which look like nothing up close. When you stand back, you can see the picture, which forms as the dots appear to merge together.
This also underscores the point that digital is not natural. Remember that old saw about the tree that falls in the woods? Just because no one hears it doesn’t mean that it doesn’t set off a vibration. Vibrations, as I said, are analog sound. Nothing in nature can set off a digital sound or picture. Even what you see is analog. Colors have wavelengths, which are after all, vibrations at a specific frequency.
What G developed was a way of enhancing and preserving the natural vibrations. What we have today is the not-natural but decidedly sharper, man-made digital sound and picture.
Technicians and philosophers may debate which is better. All I did was give you an idea of the difference. I hope it helped.