Determining the Number of Pixels You Need
High resolution or a high pixel count can be crucial but may be unnecessary in many — if not most — picture-taking situations. The trick is to match the size of the image with the demands of the printer, monitor, Internet, or e-mail service.
There is a simple answer to working with resolution. Shoot at the resolution that is appropriate for your needs but keep in mind that it's often best to set your camera to capture a pixel count at or above what you need for your final picture output. You can always delete pixels later if you want a lower image resolution, but you can't add pixels without risking damage to your image. In addition, you may want a low-res image today for use on a Web site, yet in the future you may decide you want to print the image at a larger size. Then those extra pixels will serve you well.
High resolution is very important when it comes to printing quality pictures. The highest resolution, in the example above of 3072×2304, will produce an excellent quality print of about 8″ × 10″ dimensions and a decent quality print of 11″ × 14″ dimensions. When shooting photographs for large quality prints, always use the highest resolution.
If you want to be able to crop a picture, then a higher resolution is also helpful. You can cut out a substantial amount and still have a large pixel count.
When viewing images on their own computers, many people use a graphics viewing program that may automatically resize an image for viewing so that it will fit on the computer monitor. In this case it does not really matter what resolution the image is. However, the displayed images of a high-resolution photograph will not be a true rendition of the actual image since it has been shrunk to fit the screen.
High-resolution images are bad for e-mail for a number of reasons. A high-resolution image can often not be viewed properly online as it is too big for the computer monitor. In this case, high resolution should be avoided and a low resolution such as 320×240, 480×360, or 640×480 VGA is preferred. Also, higher resolution images are much bigger and some e-mail services will not send or receive such large file sizes.
The nature of computers and the Internet is to move to higher resolution, more memory, more storage, and faster connection speeds. For example, the average monitor resolution has increased rapidly over the past few years. As these aspects advance, you will need to adjust your use of image resolution to suit the changed situation.
The standard computer monitor resolution is now 1024×768 pixels. Each pixel in a photographic image is displayed as a pixel on the computer monitor. This means that a 640×480 can be viewed easily today, although a bit small, but the next larger standard digital photography resolution of 1600×1200 is too big. The image would bleed off the screen. In this case the 1600×1200 would need to be resized so that it could be viewed properly.