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Anatomy of A Digital Camera
Resolution and File Size

When you purchase a camera, the resolution or MegaPixel quality is a major selling point.  A good standard size for early 2012 is a 12 to 14 mp camera.  Here is a chart showing the relationship of MegaPixels to image size :  

MegaPixel Resolution
in Pixels
File size
uncompressed
tif format
Approx. file size
at fine (jpg)
 resolution
Approx. # of Pictures
16gb media card can
hold at fine (jpg) resolution
10.2 3872 X 2592 28.7mb 4.8 mb 3333
16.7 4992 x 3328 50 mb 7 mb 2,285
36.3 6144 x 4912 113mb 5.5 to 9.5mb 1684
Note, shooting in RAW format will make much larger files, but higher quality

When digital cameras were first coming out, the way to gauge their quality was if they had a large megapixel size and a big zoom.  Today you want to look for low light performance and overall image quality. Before you purchase your camera, read about it online and see photo samples.  Some places online you might want to research include www.dpreview.com and photo sharing sites such as www.flickr.com  Other things that reflect the quality of the camera are the lens, the processor & sensor, display and controls and the body design.

Picture quality - To double your current resolution of photos, you need to multiply your megapixels by 4!  (I.E. there is not a huge difference of pixels between an 8mp camera and a 12mp camera.  consider buying a higher megapixel camera when the camera offers more features, such as better low light shooting and a better display). 

What are megapixels and do they matter?  MegaPixel rating is not the only factor to judge the quality of the picture.  How the MegaPixel rating is calculated - by interpolating the x and y pixels and calculating in the three basic colors (red, blue, green), can be very subjective.  How the math is calculated (algorithms) can produce great to poor quality images.  Read about the camera and compare cameras from different manufacturers often.  Sometimes products use interpolation to double their "MegaPixel resolution", where it is not really a true MegaPixel value.  For a basic way to determine megapixel size, multiply the number of the sensor rows across by the number of sensor rows up.  I.E. a camera with 3648 X 2736 microscopic sensors on a chip will equal a 10mp rating.  It will provide a file with a height of 2736 pixels by a width of 3648 pixels.

Compression - how the picture is compressed to fit on your storage device.   Most pictures are stored using jpg/JPEG  (Joint Photographic Expert Group) or "lossy" technology.  It is a type of compression that excludes picture information, so when the picture is decompressed, it is not very obvious to the human eye.  As you increase the compression, the image quality loss becomes more perceptible.  If your camera can store images without compression, it will usually store them as tif/tiff (Tagged Image File Format) files.  My favorite file type is the RAW or digital negative which yields better results than a jpg file, but is much larger. 

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contents copyright Andy Pischalnikoff

Last updated 01/06/2013