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Old 30th March 2010, 20:40   #9  |  Link
FredThompson
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Location: Charlotte, NC USA
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An interlaced frame has 2 interwoven images recorded at 2 different times. Deinterlacing involves halving the temporal information. Interpolation is, in essence, a calculated guess of the value of pixels.

Motion interpolation is a method of calculating those "missing" pixels. Those are 2 different things.

Look at an interlaced frame of an object in motion. The upper and lower frames record different periods in time.

Interlaced video has twice the number of "pictures" and half the "resolution" as progressive video.

Once you've deinterlaced you cannot reconstruct the original data so you throw away half the temporal data which means the appearance of motion during playback is less.

To illustrate: use a screen capture utility set to 15 fps and record a non-linear motion (move your mouse, for example.) Then repeat at 30 fps then at 60 fps. Which is smoohter during playback?

Real world objects in motion almost never move in a linear motion in a perfect arc around a video camera.

A flat screen is a progressive display device, true. However, that does not change the result of modifying a data set. Once you reduce the accuracy of your data, you can't recover the original data.

The human eye is better at discerning motion than color, better at edge detection than shade, right?

If you double the frame rate and interpolate the "missing" pixels the result is far more pleasing to view than if you throw away half the temporal information.

Remember, video is a projection of a 3-dimensional data set onto a plane.
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