Since digicams are being marketed like computers, each passing year brings new models with added features at lower cost. Last year, 2 MegaPixel cameras were the rage and you’d pay about US$1,000 for one. As you read this, you can get the same resolution in a digicam that’s better and faster for about half that. In fact wait a couple of months or so and you’ll probably get it for even less.

So even if you think you’ll only need a low resolution digicam, you should consider buying one with as high a resolution as you can afford, especially if there’s a possibility you may want to make photographic prints 6 by 9 inches or larger (and you will). I would put 2-MegaPixels as a minimum resolution choice. Next in line, a 3- MegaPixel camera. And finally, any higher resolution (like the new Olympus 4-MegaPixel E-10) that your heart desires– and your pocketbook can handle. Incidentally, almost all digicams offer a choice of both high and low resolution modes. Use the higher one if you want prints and the lower one for web images or for sending photos as email attachments.

Compression And File Sizes

Of course, the higher the resolution, the larger the file size– even though most images are compressed in the camera after they’re taken using JPEG (Joint Photographic Experts Group) encoding. Your file sizes will depend on the specific image and its degree of compression. Most digicams allow you to select different compression settings for different resolutions depending on the ultimate picture quality you want. On many digicams for example, available compression ratios are 1:4 (Fine), 1:8 (Normal), and 1:16 (Basic), with less compression being better than more.

Shooting in the camera’s high resolution mode, you’ll usually have three compression choices. At low resolution settings, you might have three more. If you want to print big pictures, always choose the highest resolution setting with the least compression to get the best image quality. But if your pictures are usually printed at more modest sizes, select a higher compression ratio which will let you fit more images on the camera’s memory card.

Some of the latest digicams can be set to shoot in an uncompressed TIFF mode should you want to squeeze every last pixel of quality from the image. But you’ll only get a few pictures on the memory card and, in most cases, you won’t be able to tell the difference in quality. Use this feature sparingly.

When a compressed image is uncompressed, it will be roughly five to twenty times larger than its compressed size. A 640 by 480 pixel image compressed to 50K will inflate to about 900K when opened in an image editing program. A 1024 by 768 pixel image compressed to 200K expands to 2.25MB. At 1280 by 1024, a 600K JPEG mushrooms to 3.75MB. When you get over 2-MegaPixels, file sizes of 5.5MB per image or more are not unusual (a good reason to buy an Iomega Zip drive or Zip CD along with plenty of disks).