Consumers shopping for a digital camera are frequently advised to look for high megapixel ratings, but the more expensive prices of high-megapixel cameras can be a deterrent to some shoppers. Instead, some frugal consumers choose to purchase a lower megapixel camera and enlarge the resulting photos to meet their needs. Due to technological limitations, however, this process requires a number of important considerations.
About Megapixels
When a digital camera captures a scene, it creates the digital image using a number of small, almost microscopic dots known as picture elements (commonly abbreviated as "pixels"). Each pixel carries a tiny component of the larger image and, alone, is almost invisible to an unaided viewer, but a number of colored pixels arranged in proximity to one another can digitally recreate the captured image with very high accuracy. As newer cameras produce larger and larger photos, the number of pixel elements needed to recreate images grows. A number of other factors affect the quality of the image, including the quality of the camera itself and the resolution of the digital image.
About Resolution
When a digital image is captured (and, specifically, when it is printed), a pre-defined number of pixels are packed into each inch of viewable area. The number of pixels in any given section of the image is commonly referred to as the number of "dots per inch," or DPI. Photo-quality images, or those not readily distinguished from a film camera image, typically have at least 300 pixels per inch, or 300 DPI. Under most conditions, the higher the number of pixels per inch in an image, the clearer and sharper the image appears to a viewer; the measurement of an image's DPI is generally referred to as its "resolution."
Photo Enlargement
The photo enlarging process generates a bigger photo by manipulating the space between the pixels used to recreate the image. Rather than simply magnifying the image, however, most photo enlargement processes work by increasing the space between pixels, ultimately increasing the overall size of the image. Depending on the number of pixels in the original image, some photos can be enlarged to as much as several hundred times its original size.
Effects
As a photo is enlarged and the space between the component pixels is increased, the number of dots per inch, or the photo's resolution, is decreased. Because the resolution is a measurement of how sharp and clear a photo appears, lowering the image's resolution causes it to appear increasingly blurry, grainy and, in digital terms, pixilated. According to photo experts at B&H Photo and Video, a one-megapixel image can only be enlarged to approximately four inches by six inches (4x6) before its resolution becomes too low to be considered "photo quality."
Comparison
For many home users and small print jobs, basic photo enlargement can still create photo-quality images; a five-megapixel photo, for example, can be enlarged to eight inches by ten inches (8x10) before it loses photo-quality resolution. As the megapixel count increases, so does the size of high-quality images; an eight-megapixel camera produces images that can be enlarged to 16 by 20 inches (16x20) at photo quality, and photos from a 10-megapixel model can be enlarged to 20 inches by 30 inches (20x30) with no noticeable loss of quality. Users who wish to create larger images, however, should consider using a camera with a higher megapixel count, a configuration that allows for considerable enlargement of the image while still maintaining a photo-quality resolution.
Tags: number pixels, digital image, inches inches, space between, between pixels, digital camera
