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Digital Imaging

At the time of this writing, there are three "affordable" approaches to getting photographs into electronic form. They are: flatbed scanning from photographic prints, video capture from a camcorder or tape using a computer, and having a Photo CD made from negatives or slides.

Flatbed Scanning

At one point, this was the undisputed popular choice, because scanners are cheap, and anyone can shoot prints. Once you buy the scanner (or use your company's), each transfer is free. You can get very high resolution by scanning from a big print (i.e., 8x10). The downside of scanning is that the final image is second or third generation, having gone from the camera to the negative (or slide) to print to scan. (You also have to be able to take good pictures to begin with, get them developed, etc.)

Slide scanners are also available, but they are higher-priced and not as easy to find at work or school. The university I used to haunt wanted $10 a scan for slides, and the resulting image was given to me on four floppy disks!

Video Digitizing

Nowadays, many are using video to publish on the web. This is a great deal if you already have a camcorder and computer, not so great if you have to purchase one just for this purpose. The one additional piece needed is a video digitizer (one popular type is the Snappy).

What can I say about the advantages of video? The process is very fast. You don't need to get anything developed; what you see in the viewfinder is mostly what you get. This is especially nice if you need to get a picture up quickly (for me, this is the weekend before photo deadline on our club's newsletter). Some camcorders can focus much more closely than the corresponding still camera; I can get pictures of fry on video that would never be possible otherwise. Lastly, you can shoot several minutes of video, and go back to find precisely the right frame on the tape. Video is an easy way for someone to get into digital images.

So what's wrong with it? You'll notice I don't keep many video images here... this is because I am generally not satisfied by the quality of the final product. Video itself has a resolution limit of about 640x480, though in practice you do get only 320x240 worth of information. Individual frames have a lot of noise as well, something you don't see when they are in motion. Video tape only degrades this quality (how much depends on the recorder and tape; Hi-8 is the best quality, VHS the worst). The CCDs used to record the image in the camera have limited dynamic range, which is why video has a tendency to easily wash out in the foreground and background (lately I have taken to doing a lot of processing on video images to fix the contrast and color balance). Finally, you cannot take flash pictures, so the best "shutter speed" is 1/60 second.

Low-end "Consumer" digital cameras have similar performance to video, though they do not suffer from the problems of the video tape, and some feature flashes. On the down side, most of them are fixed-focus lenses which cannot get close enough to take good fish pictures.

We are probably on the verge of a revolution, with high-end digital cameras entering the market that have overcome the problems. At this time, they're still pretty expensive for the consumer.

Photo-CD

Photo-CD came out a few years ago, initially sold as a way for families to watch their pictures on their cruddy TV...but Photo-CD is far more than this! You can either get a the images transferred directly when your film is processed, or transfer just the ones you want later (much cheaper!) from the negatives our slides, just like reprints. The images are scanned directly from the negative or slide, and have a resolution of up to 2000x3000, comparable to the grain in the original emulsion! The quality is not quite "pro" level, but is far better than flatbed scanning. The disc can be read on any computer with a CD-ROM, and you don't have to store the originals on your hard drive.

There is always a downside, of course. It costs money (these days, between $1 and $2 per scan). And it takes time (1-2 weeks) to get the disc done, because it gets sent to Kodak. And you have to be able to take photographs on a normal camera.

Some places (for instance, Seattle Filmworks) are offering digital images on floppy disk with your prints. Take heed that these are not of the same quality as Photo-CD, and should be considered comparable to flatbed scanning.

Scanning Line Art

Here's a little trick I use to scan black and white line art: Use a FAX machine! I take the graphic and use a xerox machine to blow it up to fit a full 8-1/2 x 11 page, then FAX it to my computer (which has a FAX modem). Then I take the image on the other end and do whatever tweaking I need (including filling in areas with color, taking out noise, etc). The only trick is that to get full resolution, the FAX machine usually has to be set to "Fine" or "Detail". This trick doesn't work for photos or color art, because they require grayscale or depth, while the FAX machine is only good at black & white.

Some comparisons

Here's an example: This photo of my tank was a slide that was made into a 4x6" print and then scanned. Here is the Photo-CD version, taken directly from the slide.

Here's an illustration of the resolution. This is a reduced-size full frame, and a close-up at full resolution.

More examples from my initial tests can be seen in the Greater Seattle Aquarium Society Art Gallery, and you can find numerous later examples of all four methods sprinked throughout the Krib. If you are interested in having some of your slides (or negatives) scanned for web articles, drop me a line.

E.O.
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This page was last updated 29 October 1998