Does rotating images in XP degrade quality?

[Icarus]

Hi there,

I'm trying to find out for certain whether using the "rotate clockwise" or
"rotate anti-clockwise" command in WinXP (home), actually degrades quality
or not. There IS a way to rotate jpg images without loosing quality but I'm
not sure if XP does that.

 

[Lanwench [MVP - Exchange]]

I don't think it does a thing to the image quality. What makes you think
otherwise?

 

[Jim Macklin]

90 degree rotations don't require changes to the quality,
but a rotation that is any other number of degrees requires
that pixels be recalculated so there may be degradation.


--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.


| Hi there,
|
| I'm trying to find out for certain whether using the
"rotate clockwise" or
| "rotate anti-clockwise" command in WinXP (home), actually
degrades quality
| or not. There IS a way to rotate jpg images without
loosing quality but I'm
| not sure if XP does that.
|
|
|

 

[Alex Nichol]

I'm trying to find out for certain whether using the "rotate clockwise" or
"rotate anti-clockwise" command in WinXP (home), actually degrades quality
or not. There IS a way to rotate jpg images without loosing quality but I'm
not sure if XP does that.

JPG is built on a matrix of cells, 8 pixels square. As long as a
picture is a multiple of 8 in both directions (and most are) they can be
rotated 90 degrees without loss. XP's inbuilt rotation will do this,
and if the image is *not* a multiple of 8 will warn you that there may
be a permanent reduction in quality