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Digital Megapixels / Resolution
Digital Megapixels / Resolution is the most hyped, and less understood parameter in digital camera selection. More is better? Not always. Without a doubt, higher-resolution digital cameras from the same manufacture with the same optics will produce sharper, cleaner pictures, but we are not in 1998 - most new brand name consumer digital cameras sold now are high-resolution, and most people are not using their full capabilities as is! In addition, there are a few drawbacks that you should keep in mind.
- Higher resolution cameras are more expensive than lower resolution digital cameras. We keep telling our customers - pay for what you will actually use!
- Higher resolution digital cameras of the same type / brand will work slower than their lower resolution brothers. It takes more time to process, compress, and save a larger image. We do know people who take high-res photos, transfer them to their PC's, and then immediately resize them to make them usable for emailing, storage, editing, or web publishing.
- Higher Resolution digital cameras do need more storage. Again, we will be happy to sell you a larger flash memory cards, in fact we do recommend them as a good upgrade, but get what you need! Read more on it below.
Understanding Megapixels
Most digital cameras store digital pictures in JPEG (JPG) format. JPEG image format can easily provide 20:1 compression of full-color data. The second fundamental advantage of JPEG is that it stores full color information: 24 bits/pixel (16 million colors). However, unlike TIFF or RAW digital image formats, JPEG uses "lossy compression." For full-color images, the uncompressed data is normally 24 bits/pixel. The best known lossless compression methods can compress such data about 2:1 on average. JPEG can typically achieve 10:1 to 20:1 compression without visible loss, bringing the effective storage requirement down to 1 to 2 bits/pixel. 30:1 to 50:1 compression is possible with small to moderate defects, while for very-low-quality purposes such as previews or archive indexes, 100:1 compression is quite feasible. An image compressed 100:1 with JPEG takes up the same space as a full-color one-tenth-scale thumbnail image, yet it retains much more detail than such a thumbnail. The only real disadvantage of JPEG's lossy compression is that if you for some reason repeatedly compress and decompress an image, you lose a little more quality each time.
So for all practical purposes, you got nothing to worry about - JPEG is more than capable of storing mind-blowingly high-quality pictures without any visible loss to the human eye.
MegaPixel Resolution
Why did we tell you all that technical stuff about JPEG? Because we want you to understand why most digital cameras list MegaPixels (MP) (resolution or maximum number of dots, in millions, that a digital camera can make up the image in) as their key technical parameter. Most digital cameras capture images on a CCD (Charge Coupled Device) sensor. The camera's resolution is calculated by multiplying the maximum number of pixels along the length and width of the CCD sensor. Modern digital cameras and digital binoculars typically capture between one million and seven million pixels per image, and also have a setting to lower effective resolution of the camera.
Optical Resolution vs. Interpolated Resolution
As with optical and digital zoom, many consumers are confused when they see cameras that are listed at more than one resolution. When you review and compare digital cameras, make sure if the camera resolution listed as optical or interpolated (we at OpticsPlanet.com always do!). A camera with two megapixels of optical resolution in CCD will use two megapixels of information to represent an image, while the same camera can be tweaked to have three megapixels of interpolated resolution. This is normally done through interpolation software which through specific image algorithms guesses what a digital image would look like at a higher resolution and then inserts pixels between the ones already representing the photo. Modern image software can increase picture quality, but will reduce the sharpness as up to one third of the pixels can be the pixels that the algorithm has decided to insert. Images with a highly interpolated resolution might often look blurred when enlarged. When buying a digital camera or a digital binocular camera remember that it is the optical resolution, not the interpolated resolution that gives you a true measure of a digital camera sharpness and resolution.
