PanoTools mailing list archive

PanoTools NG: Re: Re: Some more tests on Optimal Cubefaces. Thomas Rauscher 2008-Nov-01 18:52:42

Erik Krause wrote, On 01.11.2008 14:52 Uhr:

> BTW.: While photoshop creats nice small JPEGs at good quality it 
> might be no good idea to use it for cubefaces stripes. In any stripe 
> there are at least two joints where the single cubefaces don't fit. 
> At these joints the jpeg compression creates artifacts that are later 
> visible in the resulting panorama. See 
> http://www.photopla.net/wwp0703/stripes.php for details.
> 
> If I remember correctly Pano2VR and Pano2QTVR create stripes using a 
> different compression scheme near the edges, which avoids these 
> artifacts. 

The reason for these artifacts is chroma subsampling 
http://en.wikipedia.org/wiki/Chroma_subsampling .
In Pano2VR and Pano2QTVR the subsampling is turned off for stripes. 
Please note that the tile size must be a multiple of 16 to make this work.

In Photoshop different levels of subsampling are used depending of the 
quality setting. To be on the safe side with CS2 you need to use at 
least Quality 7 in "Save as..." and Quality 51 in "Save for Web". For 
more information you may also have a look at:
http://www.impulseadventure.com/photo/chroma-subsampling.html

-- 
MfG,
      Thomas

------------------------------------

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