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Windows XP image rotate

 
 
JK
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      09-02-2003
When an image file is double clicked, the image opens.
Is the rotate feature incorporated in this loss less for Jpgs?

 
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shakewell
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      09-02-2003
"JK" <(E-Mail Removed)> wrote:
> When an image file is double clicked, the image opens.
> Is the rotate feature incorporated in this loss less for Jpgs?


Unfortunately, it doesn't use lossless rotate. Try it with a test image - a
couple of rotations later, you'll notice the problem.

F=_
--
People that worry about the past are still living there.


 
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Ken Davey
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      09-02-2003

"JK" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> When an image file is double clicked, the image opens.
> Is the rotate feature incorporated in this loss less for Jpgs?
>

No!


 
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JK
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      09-02-2003
I am still not convinced that it is not lossless. I rotated an image 100
times, and I have not noticed any visible signs of degradation.
If it is lossy, it appears to be extremely minimally lossy.

shakewell wrote:

> "JK" <(E-Mail Removed)> wrote:
> > When an image file is double clicked, the image opens.
> > Is the rotate feature incorporated in this loss less for Jpgs?

>
> Unfortunately, it doesn't use lossless rotate. Try it with a test image - a
> couple of rotations later, you'll notice the problem.
>
> F=_
> --
> People that worry about the past are still living there.


 
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David Lewis
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      09-02-2003
JK wrote:
> When an image file is double clicked, the image opens.
> Is the rotate feature incorporated in this loss less for Jpgs?


My understanding is that it will induce losses only if changes are saved i.e
you"ve edited the JPEG.I don't think XP photo viewer saves the changes,does
it?

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Kind Regards,
David



 
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JK
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      09-02-2003
It does save the changes. I know it is possible to rotate jpg images without
a loss. When doing my rotation experiment, I noticed that the image size
followed a patern and kept reverting to the same numbers, which is
probably another clue that it might be lossless? If it is lossy, the loss might
be extremely small, as I didn't notice any image degradation after 100
rotations.

David Lewis wrote:

> JK wrote:
> > When an image file is double clicked, the image opens.
> > Is the rotate feature incorporated in this loss less for Jpgs?

>
> My understanding is that it will induce losses only if changes are saved i.e
> you"ve edited the JPEG.I don't think XP photo viewer saves the changes,does
> it?
>
> --
> Kind Regards,
> David


 
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David Lewis
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      09-02-2003
JK wrote:
> It does save the changes.


Yes,I checked with my jpegs and it also saves the changes.What threw me was
that it doesn't save changes for TIFF images.I have no idea why this should
be.

>I know it is possible to rotate jpg images
> without
> a loss. When doing my rotation experiment, I noticed that the image
> size followed a patern and kept reverting to the same numbers, which
> is
> probably another clue that it might be lossless? If it is lossy, the
> loss might be extremely small, as I didn't notice any image
> degradation after 100 rotations.


What you see is what you get :>) It is probable(?) that mere rotation
doesn't introduce much degredation but, given jpeg is a lossy form of
compression, perhaps would be more noticeable with larger image manipulation
changes?

--
Kind Regards,
David



 
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Lucas Tam
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      09-02-2003
"Bryce" <(E-Mail Removed)> wrote in news:Mv45b.21$xe6.25989
@news.uswest.net:

> I've just rotated one 20 times.
>
> I haven't noticed anything yet.
>
> (yes, I have a couple extra minutes on my hands right now)
>
>
> I can assure you that I don't have a "special version" of xp.


I think it depends on the size of the JPEG, here is an error I got:

Windows Picture and Fax Viewer:

Because of the dimension of this picture, rotating it might permanently
reduce its quality. Rotating a picture automatically saves it using the
original name. blah blah blah...


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Lucas Tam ((E-Mail Removed))
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Lucas Tam
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      09-02-2003
"Bryce" <(E-Mail Removed)> wrote in news:9I75b.39$xe6.39479
@news.uswest.net:

> So, it might be dimension dependent?



Yeah, I believe the image dimensions must be divisibe by 16 (or some
factor) if you wish to rotate the picture.

I tried rotating a 1600x1600 picture and had no warnings : )

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Lucas Tam ((E-Mail Removed))
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JK
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      09-03-2003
I was wondering if this might be the case, although my sample image
varied in size through the rotations by up to 1%, and even more interestingly
the size followed a pattern when the same 6 numbers for file size kept
appearing through the 100 rotations. I don't understand why there would
be 6 different numbers for file size and not just 4.

Andrew Koenig wrote:

> JK> When an image file is double clicked, the image opens.
> JK> Is the rotate feature incorporated in this loss less for Jpgs?
>
> I believe that at least one of the Windows XP features doesn't rotate
> the image at all -- it just sets the header bits that indicate orientation.
> Some viewing programs honor those bits; others don't.
>
> --
> Andrew Koenig, http://www.velocityreviews.com/forums/(E-Mail Removed)


 
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