Image Size and Compression
Most digital cameras are capable of capturing images at various resolutions, typically ranging from low-res screen resolutions of 640 by 480 to high-res, print-quality resolutions. In addition, most digital cameras offer varying degrees of image compression, to allow you to fit more pictures onto their removable storage cards. In short, image resolution and compression are two additional choices you’ll need to consider when shooting digital.
Choosing resolution and compression is not as big a deal as it may seem: You’ll most likely select settings based on your output needs and then stick with them for the duration of your shoot. For example, if you know your images are destined for the Web, you might decide to shoot at a lower resolution, not only to get more images on your card, but to save yourself time “rezzing down” later. However, if you commit to a lower resolution, you will have a difficult — if not impossible — time if you need to re-purpose those images for high-quality printing.
However, if you elect to always shoot at the highest possible resolution, then you won’t be able to shoot as many images with a given amount of storage space. The answer to this concern, of course, is to use more compression. However, because most cameras use a “lossy” JPEG form of compression (lossy means the compression involves discarding some of the color information in each image to save space), you’ll lower image quality somewhat when you increase compression level.
To help ensure you get the image quality you need, it’s probably best to shoot at the highest resolution and best quality that your camera can manage. This will afford you the most flexibility in using and re-purposing your images. Only if storage becomes a concern should you consider changing compression or image-size settings.
If you can’t go with the highest-quality settings when shooting for the Web, leave compression at a high-quality setting and lower the camera’s resolution. This will result in smaller files but won’t compromise image quality. If you’re shooting for print, leave your image size the same and bump up your level of compression. Though increasing compression will introduce artifacts into your images, this is not as bad as lacking adequate resolution to print at the size you need.
Most cameras will remember your image size and compression settings even after the camera has been turned off. If yours doesn’t, then you’ll need to get in the habit of checking these settings when you power up the camera, unless you plan on always shooting with the default settings.
Most photographers are concerned about capacity when they first consider the jump to digital. But with removable media becoming ever cheaper, this is now less of a problem. If you do need to shoot lots of pictures in the field, consider taking a laptop with you, or a portable mass storage device such as the Minds@Work Digital Wallet. Bear in mind, also, that because you can delete unacceptable images on the fly, a given number of exposures on a digital camera will typically go further than the same number of exposures on film.
This article was last modified on December 14, 2022
This article was first published on April 17, 2001
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