Home > Archive > Compression > October 2006 > Re: "Real WMV", 148.50 mhz sample-rate, 1920 X 1080 progressive scan image,
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Re: "Real WMV", 148.50 mhz sample-rate, 1920 X 1080 progressive scan image,
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| Radium 2006-10-30, 6:56 pm |
| Bob Myers wrote:
> The blocky-looking artifacts that result from some compression
> schemes are not the result of "pixelization" per se; they come about
> because these schemes are based on transforming a block of
> pixels (such as an 8 x 8 or 16 x 16 pixel square) into a more
> compact form, all across the image. But you can push the
> compression algorithm too far, to the point where there is no longer
> sufficient information to accurately recover that block of pixels
> - and so the block itself becomes visible.
The blocks become visible during compression if the image-resolution is
the thing being compressed. If it is the color-depth [instead of the
image-resolution] that is compressed, then there will be no appearance
of blocks [provided the image-resolution is sufficient] no matter how
far the compression of color-depth is pushed.
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