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| − | '''Lossy versus Lossless Images: What is the difference?''' | + | == '''Lossy versus Lossless Images: What is the difference?''' == |
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| + | As "analog" 35 mm cameras (and the film used for it!) become more and obsolete, digital cameras and the storage and transmission of digital images are rapidly becoming the de facto standard for today's photography needs. | ||
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| + | The resolution of a camera - e.g. 6 MP (Megapixel) or 10 MP - determines the number of pixels the camera uses to represent the "continuous" signal (e.g. a mountain, or your smiling significant other) that your digital camera is sampling. | ||
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| + | Thus the digital camera samples the continuous signal, with a period <math>T</math> (shutter speed) and on for length <math>tau</math> (related to aperture -- how much light is absorbed): | ||
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| + | ''' | ||
| + | <math>X_s(t) = s_{tau}(t)x(t)</math>''' | ||
| + | (Note: image is two-dimensional signal) | ||
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| + | A digital camera also quantizes the sampled values, because an infinite amount of storage space (i.e. bits) is not available to represent every pixel. A typical digital camera will allocate 24 bits per pixel, thus allowing: | ||
| + | <math>2^{24} = 16,777,216</math> possible color representations. | ||
Revision as of 15:00, 22 September 2009
Lossy versus Lossless Images: What is the difference?
As "analog" 35 mm cameras (and the film used for it!) become more and obsolete, digital cameras and the storage and transmission of digital images are rapidly becoming the de facto standard for today's photography needs.
The resolution of a camera - e.g. 6 MP (Megapixel) or 10 MP - determines the number of pixels the camera uses to represent the "continuous" signal (e.g. a mountain, or your smiling significant other) that your digital camera is sampling.
Thus the digital camera samples the continuous signal, with a period $ T $ (shutter speed) and on for length $ tau $ (related to aperture -- how much light is absorbed):
$ X_s(t) = s_{tau}(t)x(t) $ (Note: image is two-dimensional signal)
A digital camera also quantizes the sampled values, because an infinite amount of storage space (i.e. bits) is not available to represent every pixel. A typical digital camera will allocate 24 bits per pixel, thus allowing: $ 2^{24} = 16,777,216 $ possible color representations.
