P3D Re: Scanned Stereo pair manipulation software...

[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

>Date: Mon, 30 Mar 1998 04:04:37 -0700
>From: Dylan The Hippy Wabbit <spacey@xxxxxxxxxxxxx>
>Subject: P3D Re:  Scanned Stereo pair manipulation software...

>Dan Shelley wrote:-

>>6 - Save in your output file type of choice. For this example, I would
>>save as an uncompressed JPG.

>There is no such animal as an uncompressed JPG.  I know the compression
>setting control often reads 0-99, but it's just an arbitrary number.
>You're not meant to take it literally.  You might mean "Set the
>compression to it's minimum."  If you do you are probably throwing the
>baby out with the bath water.  A moderate compression setting will save
>quite a bit of space (and web server bandwidth) without having any visible
>effect.

>Dave Spacey

But I believe there's such a thing as *lossless* JPG - perhaps that was
what was meant.

(There's no lossless compression algorithm that can be relied upon to reduce
the file size of *any* arbitrary image, but there are algorithms that will
reduce the file size for just about any image you're likely to encounter.
Generally speaking, most any compression above about 2:1 will lose some
image information, though that loss may not be readily apparent. As you
mentioned, very high lossy compresion ratios can often still produce
acceptable results.)

John R


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