Deinterlacing methods (II)

Adaptive Deinterlacing

This method analyzes the video and determines when mice teeth should be blurred (usually on movement) or when preserving sharpness is appropriate.

The algorithm must be well optimized, otherwise good parts of the video can be removed by accident or the image can become very blurred at fast movement.

Bob

This technique simply separates the two fields and places them in two separate frames, effectively doubling the video's frame rate.

The height of the image is reduced by half yet the video is very fluid and sharp.

Because one of the fields is one scan line below the other field, there is a possibility for video artifacts to "jump", effect usually noticed on TV logos.

A very powerful computer to play a compressed video deinterlaced with this method: the video codec must be able to handle twice the number of original frames per second and resize the images to the original height at the same time.

This deinterlace method, combined with the Weave method, usually produce the highest quality results.

Resizing to a lower resolution

Well, it's not really a deinterlacing method - in fact any video processing application can do this - but it does guarantee that the interlacing effects disappear.

According to standards, a video that is exactly or less than 384x288 pixels can not be interlaced: resizing to this resolution or to a lower resolution (but preserving the aspect-ratio) assures a interlace-free video.

It's a very easy solution and the only negative effect is that a bit of quality is lost (usually the horizontal width is reduced by half).

Motion compensation

This last method is also the most complex: it is supposed to analyze the contents of each field and determine the objects inside the images, then to deinterlace the images full spatial resolution without loss of image resolution.

This method is very processor intensive, it takes about 40 seconds to deinterlace one second of video on an average computer using the only available application designed to do this: HiCon³², from Fraunhofer Labs, the inventors of the MP3 format.

The results are amazing, crisp, sharp images without signs of interlaced material, however, if you really need it, you're better using expensive hardware solutions.

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