Megapixel Math
There is probably no more important digital camera feature than the image sensor the charge coupled device (CCD). The size and construction of these tiny CCD chips, measured in pixel dimension, dictates the resulting images resolution and, therefore the size of acceptable prints the camera is capable of printing. The CCD is like the cameras permanent roll of film, so its quality is extremely important.
Only a few short years ago, 1-megapixel cameras ( those with one-million-pixel CCDs) were unheard of. Now the industry has advanced to 3- and 4-megapixel cameras for less than the cost of some 35mm SLRs. Each manufacturer claims its own cameras results are best but, in fact, many of them use the same CCDs and customize each camera with their own special features. If youre comparing cameras with identical chips, its those features that will make the difference when it comes time to decide which one is right for you.
If you want a camera to capture snapshots for posting on a web site, and perhaps small 3x5 or 4x6 prints, a 1-megapixel camera will have more than enough resolution. But if what you want is a camera that will work with a desktop inkjet printer to produce high quality printouts at larger sizes, more pixels are paramount. In terms of exactly matching the results of a 35mm camera and traditional lab printing, it takes a whole lot of pixels. For most purposes though, youll probably be satisfied with enlargements from a camera with a chip that, in sheer numbers anyway, may not provide all the pixels needed for printing.
For example, the new 3-megapixel cameras will make very good 8x10 prints even though the mathematics involved with the pixels dictates that the prints should be limited to 5x7-inches. Technically, to match film quality, a 5-megapixel camera is required. But in reality, a great print can be achieved with only a 3-megapixel camera. The detail in film based printing is tremendous, but unless youre holding a lab-made silver print next to its inkjet duplicate, youll probably be hard pressed to find many flaws with the digital version. Thats why you can get away with fewer pixels than the mathematics may require. In short, the more pixels a cameras CCD has, the bigger the prints you'll be able to make.
Different digital cameras may capture photographs on the same CCD, but the way they are process and store those images makes a big difference in overall quality. Some cameras only record in a JPEG compression mode to get more pictures on a single memory card. But theres a tradeoff in order to gain that storage space-quality. JPEG compression creates artifacts, evidence that technology has altered the original image (such as blotchiness in what should be a uniform blue sky). Look for cameras that offer the ability to capture images with low compression or without compression, usually as TIFF files. True, you cant get as many pictures on a single memory card, but image quality is maximized. TIFF images allow you to retain for printing all the details that the megapixel CCD captures. Some digital cameras actually offer increased resolution beyond the size of their CCDs. Thats achieved by interpolation. It may sound like an ideal feature, but this process grows the size of the image by guessing what should fill the gaps between pixels. The results are acceptable for eking out a bit extra on print size, but this feature shouldnt be considered a substitute of actual CCD pixels. The best method for expanding print size beyond what the pixels will allow is to use a res-up program in the computer, such ass Genuine Fractals PrintPro or LizardTechs Mr. SID. These programs more accurately allow you to expand file sizes, but their abilities are limited. The bottom line is this: If you want a big print, get a camera with more pixels
Pixel Size File Size Acceptable Print Size
640x480 900k 2x3 Small
1024x768 2mb 3x5 2x3
1-megapixel 3mb 4x6 3x5
2-megapixel 6mb 5x7 4x6
3-megapixel 9mb 8x10 5x7
6-megapixel 20mb 11x14 8x10
Visit www.kodak.com to see Kodak's, The Guide To Better Pictures. Start by clicking Taking Great Pictures. |
