Megapixels and Why dSLRs Have More of Them
If you’ve been working with digital images for a
while, you know that pixels are your pals. They’re
the basic building blocks that make up an image. The
term pixel is a portmanteau, which was Lewis Carroll’s
term for a new word created by combining two old
words, such as slimy and lithe to create slithy. In this case,
pixel stands for picture element and came into vogue when
computer imaging became popular.
However, you’ve seen pixel-like components outside the digital realm, in
pointillist paintings, such as the illustrations Georges Seurat created for the
Broadway musical Sunday in the Park with George. You also see pixel-like
components in newspaper halftone photos. All these images are made up of tiny dots that you can see vividly up close, but those dots blend to create
continuous tones and colors when you view them from a distance,The difference between these picture elements and those used to represent digital photos is that the digital pixels are all the same size
and shape, varying only in brightness and hue.
In digital images, the pixels — tiny squares that you can see individually only
under magnification — are arranged in rows and columns like a checkerboard
that happens to measure hundreds of squares on a side. Among current digital
SLRs, this array is a minimum of 3,008 pixels wide and 2,000 pixels tall,
for a total of 6 million pixels in all. (Although the last of these 6-megapixel
cameras will probably be phased out early in the life of this book.) The latest
digital SLR cameras for consumers actually offer many more pixels than that,
from 3,872 x 2,592 (10 million) pixels for certain entry-level models to 4,288
x 2,848 (12 million) pixels or more for the majority of digital SLRs. Of course,
pro and advanced amateur cameras go up to 6,048 x 4,032 (24.5 million)
pixels. That’s a lot of pixels! Those pixel counts represent the number of light-sensitive areas in the
digital camera’s sensor, and the total is usually expressed in terms of megapixels
(millions of pixels), and abbreviated MP. The precise dimensions
might vary, depending on the exact sensor used. For example, the Nikon D40
uses a 3,008-x-2,000-pixel sensor, but the original Canon Digital Rebel had a
3,072-x-2,048-pixel array. Both cameras were considered 6MP dSLRs, even
though the arrangement and number of pixels is slightly different.
Pixelementary, my dear Watson
Pixels, represented by individual
light-sensitive areas in a sensor
called photosites, capture the detail
in your image. In general terms,
the more megapixels, the better
because when you add pixels, the
ability of the sensor to capture detail
improves and the effective resolution
of the sensor rises.
It’s like dividing a foot-long ruler into
1,200 increments rather than 120.
In the former case, the ruler could
measure things with 1/100-of-an-inch
accuracy; in the latter, you could
use the rulings only in 1/10-of-an-inch
chunks. In the same vein, a sensor of
a particular size that has 12MP can
show much finer detail than one the
same size that has only 6MP. when
the size of the pixels decrease, more
of them can fit on a sensor to capture
ever smaller details of the original
image. However, image quality
involves more than resolution alone.
Many 10MP dSLRs produce sharper
and more noise-free results than
12MP non-dSLRs simply because the
10MP dSLR’s sensors are physically
larger and each individual pixel is
better than a non-dSLR’s sensor’s.
Some dSLRs even outperform other
dSLRs that have more resolution
because of the quality of the sensors,
lenses, or electronic circuitry in the outperforming dSLR. For example, I have a 12MP pro dSLR that consistently
produces better results than a 14MP entry-level model from another vendor,
particularly under lower light levels. The raw number of megapixels gives
you only a guideline, even though the more pixels, quite often the better your
images look.
Article From : Digital SLR Cameras and Photography For Dummies 3rd Ed. (Book)
0 comments:
Post a Comment