YOUR FIRST DIGITAL CAMERA
Understanding how image compression works
By David Gewirtz
I have to say that our visit to the world of the digital camera has been pretty amazing. The response we've gotten from our readers has been just astounding. In this issue, we're going to look at some important concepts of image compression that you'll need to know in order to understand how to capture and save images at the best quality.
But first, I want to comment further about the reader response. Based on your letters, it looks like we're going to spin out a digital camera publication, most likely to be called "Connected Photographer." We've long been thinking about doing a series of publications on the creative arts, but our plans were quite some distance out in the future. Given your interest, we decided to kick things off much more quickly and give Connected Photographer a go.
That said, to make this puppy launch, we're going to need your help. I'm going to continue to write articles about the cameras and photography, but I definitely need other voices. If you'd like to contribute to the new magazine, please let me know at address@hidden. We have general writer guidelines at http://www.authorpower.com, but aren't yet near having a Web site in place for the new magazine. Likewise, if you know of sites who might like to link to us, or companies who might make excellent sponsors (especially if you're at one of those companies), please let us know as well.
Now, on to the wonderful, wacky world of compression.
Everything we've talked about so far has led to the inescapable conclusion that "megapixels" is all about the size of the image, in digital form. The as-yet-undiscussed secret is that an image, when captured on a digital camera, is nothing more than a file, like what you'd find on your computer. Most cameras capture in TIFF (Tagged Image File Format) format, while a few others capture in JPEG (Joint Photographic Experts Group) format.
The meaning of lossy
In general, you'll want to make sure your camera can save its image files as TIFF, because JPEG is "lossy." No, not lousy. Lossy. Lossy is actually quite good. Sometimes.
Let me explain. Quite literally, a lossy algorithm, whether we're talking about pictures or music, is one where the computer (whether on your desktop or inside your camera) is told to purposely lose some bits. I'll bet some of you are lossy right now, because you're feeling like your bits are lost. Don't worry, this is a pretty easy concept once explained.
When we digitize an image or a song, we're converting a non-digital medium (technically "analog") into a digital medium, a series of bits, or ones and zeros. When an image or sound is digitized at the highest level, the computer (through a series of digitizing peripherals) tries to capture as accurate a representation of the medium as possible. So a photograph, at the highest resolution, attempts to capture as much pixel data as possible. A song, when digitized, attempts to capture every nuance and tone of the music.
In general, at this stage of our technology, the capture can be astoundingly high quality.
So think it through. If you're capturing at very high resolution and at very high quality, you're going to be capturing a lot of data. A whole lot of data. But what if you could take that data, say from a song, and save it in a format that takes a lot less storage? We recently captured a four minute song sung by a friend. When stored in the best quality format possible, that song took up 21 megabytes. But when it was converted to MP3 format, that song took up only 969K, less than 5% of the original data size.
Incidentally, this is why the music industry is losing its collective mind. Before MP3 came about, a song took forever to download. But when you can save the song to a format that's only 5% of the original size, "forever" becomes just a few minutes. And that's why file sharing services such as Napster and Kazaa took off. The "enabling technology" was the MP3 format, and specifically the compression algorithm in MP3.
So how does it work? What magic happens that makes an MP3 take only 5% of the storage of the original? What magic makes a JPEG take a tenth of the space of a TIFF image file?
One word: compression. Two words: lossy compression.
To learn more about compression and your digital camera, click here.
GREAT STORIES
Here comes trouble
By Marilyn Gewirtz
In the beginning, when I first came to live with the family, I was on my best behavior. I did my work well and felt that I was truly loved. They gave me my own space, and it was very comfortable. I had sitting room and the proper environment to exist comfortably. I was able to function at the top of my mark and worked diligently for over a year.
I tried to behave, really, I did.
I wanted to be good. Gradually, however, little by little, I would do something nasty. I just couldn't control myself. I didn't do as I was told; went my own way. Small things would start to disappear. Nothing that would be specifically noticed; just enough to make them feel that something, they didn't know what, was amiss.
Finally, so much around me went missing, I did so many things wrong, they didn't know what to expect next. They were going to expel me from the only real home I have ever known. They'd give me one more chance, then another. But something possessed me; I couldn't stop misbehaving. When it came to the last minute, when they were ready to toss me out, they found out that I wasn't doing these awful things because I wanted to do them any harm, but because I was very, very ill.
My family didn't know what to do. At first, they still wanted me gone, but they were good hearted people. They couldn't just abandon me if I was truly sick. They tried everything they knew to cure me, to make me better. All types of experts were called in, and a little improvement was noticed. Finally, I was doing well enough to continue my life. I did my best, behaved and was allowed to remain with the family.
But once again, soon enough, as if I were possessed, I started losing bits and pieces of things. Once again it was small enough not to be noticed, until the time larger items began to vanish. I knew I was really in trouble. It was either be ousted from my cozy room and be replaced or go for some real long-term therapy.
Therapy it was. I was shipped far away from home and family. I was examined by experts in the field and with every form of modern technology. First, I was checked out externally. They found nothing to cause such problems. Then they opened me up and scanned all my insides, removing a number of infected organs. I was given transplants, replacement parts throughout my internal structure, and some of these transplanted parts were better than any I had had before.
After weeks of counseling, my family was called in, and we had joint sessions, each learning how to handle the other so we could live harmoniously. And at long last, I was sent back home. Once again, I was in my own cozy space. Once more I resolved to behave and do what I was meant to do without any fuss or argument.
I have been behaving for almost a year now, and we have all coexisted in peace. But oh, how that bug gets to me every so often. It's like a virus.
This past week I slipped again. Why am I so bad?
But I had to try it. It was something brand new. I was going to clone myself. Over and over again. It was so much fun. But I was being so wicked. I knew I was tormenting my family, but I couldn't control it. I don't know what gets into me. One of these days, if I am not careful, it could finish me off. I don't know how I will react.
But gradually, byte-by-byte, I am sure there will be trouble.
Marilyn Gewirtz is 42-year old ZATZ Editor-in-Chief David Gewirtz' mom. When asked what she wanted her bio to say, she simply answered "David is my little boy." Some things never change.
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