Understanding Digital Cameras
Digital cameras record images on computer chips comprised of rows of tiny light-sensitive cells. Also called photosites, these cells register color and light and convert them into electrical signals. How much detail a digital image can contain depends on the number of cells that are on the chip and the size of the chip itself.
The quality of the images digital cameras can produce is dependent on their megapixel capacity. One million light-sensing cells is equal to one megapixel. As pixel counts go up, images get better. If you're planning to print your images in a size larger than a 5″ × 7″, a higher megapixel model is a must.
In the digital world, image size refers both to the physical size of a picture and to its resolution. It also indicates how large prints can be before image quality degrades and they become noticeably pixilated, which is the digital equivalent of being grainy.
A pixel can be considered a unit of length. However, in this case, that unit can change. For example, an image that measures 1600 × 1200 pixels is 1600 pixels wide and 1200 pixels high. The next step is the resolution of the image. Resolution is measured in dots per inch (DPI) and refers to the number of pixels set side by side that will fit in an inch.
A typical 6 megapixel digital camera will offer five different image sizes:
2832 × 2128 pixels: Best resolution, but images contain a lot of data and take up a large amount of storage space. They're also slow to upload and download. On the plus side, images in this format will yield at least 8″ × 10″ prints.
2832 × 1888 pixels: Good resolution; will yield at least 6″ × 8″ prints.
2304 × 1728 pixels: Good resolution; will yield at least 6″ × 8″ prints.
2048 × 1536 pixels: Yields good image resolution but smaller prints. Images also display well on large monitors. Roughly 5″ × 7″ print size.
1200 × 900 pixels: Yields good image resolution but smaller prints. These images also display well on large monitors or can be used in emails. Roughly 5″ × 7″ print size.
Most cameras allow you the option of changing your picture's resolution. If you want to save space on your memory card, you can opt for a lower resolution. If you want to take high quality pictures, select the higher resolution.