Understanding Camera Resolution Options
Published: May 1, 2002
The sensor in a digital camera is composed of pixels, which are tiny light-sensitive squares. The sensors in most cameras today are made up of millions of pixels, each one registering the brightness of the light striking it as the photo is taken. The number of pixels in the image is about equal to the number of pixels on the sensor. This number is referred to as the image's resolution.
Simply put, the greater the number of pixels in an image, the higher the resolution. And the higher the resolution, the better and larger the print you can make from your Windows XP-based computer and printer. Put another way, resolution affects the output options for your photo. It's important to keep this in mind as you explore the resolution options on your camera.
Resolution Affects Output
Most digital cameras allow you to change the resolution setting, so you can fit more or fewer images on your memory card. This can be a helpful feature if you only have one card or if you are on a trip and can't transfer photos to your computer. But if you take a photo of a spectacular sunset, and you capture it on a lower resolution setting like 800x600, you may be unhappy with the result if you want a 5x7 or 8x10 print. That's because the low resolution image lacks detail, and may also appear jagged. Carrying additional memory cards and keeping the camera set on its highest resolution setting is a better solution.
The higher the photograph's resolution, the more plentiful printing and sharing options exist. With this in mind, the best bet is to shoot photos at the highest resolution your camera can capture. The resolution can easily be adjusted downward on your computer—Windows XP will do this with one click when you're sending photos in e-mail, for example. However, there is a limit to how effectively photo resolution can be adjusted upward by a computer. This means, for example, you can always make a sharp, clear, small print from a high-resolution photo, but you can't make a rich, detailed, large print from a low-resolution one.
Choosing a File Format
When you shoot a picture, the camera processes the picture data based on the white balance and other settings. Then, as its last step before transferring the photo to the memory card, the camera saves the picture into the file format you've selected. The file format you choose can impact the clarity of the photo. A number of digital cameras offer both TIFF and JPEG settings:
| • | TIFF: This file format is uncompressed. Choosing TIFF means that you're always assured of getting all the image quality captured and processed by the camera. But TIFF files can be quite large, which means that only a few will fit onto a memory card. They can also take a while to be written to the card, which, with some cameras, means it might be a few seconds before you can take another picture. |
| • | JPEG: This file format is compressed, which means that the picture information is squeezed to a smaller size before it's stored on the memory card. Though this compression does not alter the photo's resolution, it does come at the expense of a slight loss of detail and clarity in the photo. Typically, a camera will offer several JPEG settings, each offering progressively more compression (which translates into being able to store more photos on the memory card), with a commensurate drop in image quality. |
The file format you choose doesn't affect the resolution of the photo, but if you choose a JPEG setting that compresses the photo heavily, the detail in the photo may be irretrievably damaged. This type of damage is called JPEG artifacting, and often appears as a pattern of large, square blocks sprinkled through the picture. JPEG artifacting limits your ability to make a large print from the photo, even though the resolution of the photo hasn't been changed by the JPEG compression.
It would seem that shooting on the TIFF setting, if your camera offers it, is the most sensible way to eek out every ounce of quality from a digital camera. While this is true, it isn't the whole story. That's because shooting TIFF (instead of JPEG) means that you need to have lots of memory cards to shoot with, a faster memory card reader (forget "tethering", or connecting the camera directly to the computer if you're shooting TIFF), a larger hard drive to store the large files and more blank CDs since not as many TIFF files can fit on a CD as JPEG files. TIFFs can quickly become impractical.
Fortunately, the highest-quality, lowest-compression JPEG setting on most cameras offers fractionally less quality than TIFF, but without the headaches of really large photo files. In fact, few photographers ever notice the difference between a best-quality JPEG and TIFF, even though the JPEG will be six to eight times smaller when stored on the card. The same can't be said of the lower-quality JPEG settings—clarity and detail can drop off fast.
To maximize both the resolution and clarity of your photos, while not bogging down the camera and limiting its usefulness, set your camera on its highest resolution and best-quality JPEG settings.
Scanned text document
(B&W, 150 dpi, 8½x11 inches) | 268 KB JPEG | 36 KB JPEG | 126 KB JPEG |
Scanned magazine page
(grayscale, 150 dpi, 8½x11 inches) | 1.11 MB TIFF | 16 KB JPEG
(text unreadable) | 85 KB JPEG
(text readable) |
Color photo from digital camera
(24-bit color, 192 dpi, 1280x960 resolution) | 556 KB JPEG | 56 KB JPEG | 235 KB JPEG |
Scanned color photo
(24-bit color, 300 dpi, 3x5 inches) | 6 MB BMP | 12 KB JPEG | 66 KB JPEG |
Table adapted from
Microsoft Windows XP Inside Out
, by Ed Bott and Carl Siechert.
Caution Using this technique to shrink and compress an image file invariably causes a loss of data. When you're sending a snapshot to your parents, the drop in quality is probably a fair tradeoff for the faster, slimmer e-mail attachment. But if the scanned image contains text, or if the recipient wants to be able to print a high-quality copy, check the compressed image before you click Send. Where quality is crucial, you might have better results using the Zip format to compress the original file without losing any data. Or look for a third-party image editing program such as Paint Shop Pro, which gives you greater control over compression.
