Lossless Rotation

JM
Posted By
Joe Maldon
Jul 15, 2007
Views
320
Replies
7
Status
Closed
Hi,

Can someone please confirm whether or not Photoshop Elements 5.0 supports lossless rotation please.

I have googled but couldn’t find anything specific relating to version
5. There are various posts relating to this – suggestions that
lossless rotation can be done in the browser. Is this correct and can Adobe confirm this to be the case? I have also searched the Adobe website but without any joy.

Many thanks.
Related Tags
lossless rotate

How to Improve Photoshop Performance

Learn how to optimize Photoshop for maximum speed, troubleshoot common issues, and keep your projects organized so that you can work faster than ever before!

JS
James Silverton
Jul 20, 2007
Joe wrote on Sun, 15 Jul 2007 08:14:48 -0700:

JM> Can someone please confirm whether or not Photoshop JM> Elements 5.0 supports lossless rotation please.

JM> I have googled but couldn’t find anything specific relating JM> to version 5. There are various posts relating to this – JM> suggestions that lossless rotation can be done in the JM> browser. Is this correct and can Adobe confirm this to be JM> the case? I have also searched the Adobe website but JM> without any joy.

As an outsider thinking about rotation in a photoediting program for the first time, I can’t see how you can achieve an
restorable loss of color or shade information on rotation by an arbitrary angle. In principle, a grid rotated with respect to another one must sample each new cell from several cells and, once converted to a number, color information could not be restored on rotating back. There may well be algorithms that minimize losses but I don’t know them of course.

James Silverton
Potomac, Maryland

E-mail, with obvious alterations:
not.jim.silverton.at.verizon.not
F
Fishface
Jul 21, 2007
James Silverton wrote:
As an outsider thinking about rotation in a photoediting program for the first time, I can’t see how you can achieve an
restorable loss of color or shade information on rotation by an arbitrary angle. In principle, a grid rotated with respect to another one must sample each new cell from several cells and, once converted to a number, color information could not be restored on rotating back. There may well be algorithms that minimize losses but I don’t know them of course.

Irfanview offers lossless jpeg rotation through a free plug-in. Lossless jpeg rotation is only possible at 90
JS
James Silverton
Jul 21, 2007
Fishface wrote on Sat, 21 Jul 2007 22:46:22 GMT:

F> James Silverton wrote:
??>> As an outsider thinking about rotation in a photoediting ??>> program for the first time, I can’t see how you can ??>> achieve an restorable loss of color or shade information ??>> on rotation by an arbitrary angle. In principle, a grid ??>> rotated with respect to another one must sample each new ??>> cell from several cells and, once converted to a number, ??>> color information could not be restored on rotating back. ??>> There may well be algorithms that minimize losses but I ??>> don’t know them of course.

F> Irfanview offers lossless jpeg rotation through a free F> plug-in. Lossless jpeg rotation is only possible at 90°, F> 180°, 270°. I don’t have PSE 5, but I imagine they would F> mention it if the option were available. It certainly F> should be.

That is in agreement with what I thought, grids would overlap exactly at 90° intervals but not at *arbitrary* angles. Such rotations are useful but not "lossless" in the general sense.

F> Since the OP did not specifically mention lossless jpeg F> rotation, I don’t even know if this subject pertains to his F> inquiry.

James Silverton
Potomac, Maryland

E-mail, with obvious alterations:
not.jim.silverton.at.verizon.not
F
Fishface
Jul 22, 2007
James Silverton wrote:
That is in agreement with what I thought, grids would overlap exactly at 90
DS
Donald Stouder
Jul 22, 2007
On Sun, 15 Jul 2007 08:14:48 -0700, Joe Maldon
wrote:

Hi,

Can someone please confirm whether or not Photoshop Elements 5.0 supports lossless rotation please.

I have googled but couldn’t find anything specific relating to version
5. There are various posts relating to this – suggestions that
lossless rotation can be done in the browser. Is this correct and can Adobe confirm this to be the case? I have also searched the Adobe website but without any joy.

Many thanks.

Under most conditions, PSE 5 will do a lossless rotation from the Organizer. To be honest, I do not know exactly what conditions this is not true. I believe it is related to the aspect ratio of the image.

What I do know is this. When PSE can not perform a lossless rotation, it tells you and asks if you want to proceed.

Hope this helps somewhat.

Don S.
JS
James Silverton
Jul 22, 2007
Donald wrote on Sun, 22 Jul 2007 10:50:10 -0700:

??>> Hi,
??>>
??>> Can someone please confirm whether or not Photoshop ??>> Elements 5.0 supports lossless rotation please. ??>>
??>> I have googled but couldn’t find anything specific ??>> relating to version 5. There are various posts relating to ??>> this – suggestions that lossless rotation can be done in ??>> the browser. Is this correct and can Adobe confirm this to ??>> be the case? I have also searched the Adobe website but ??>> without any joy.
??>>
??>> Many thanks.

DS> Under most conditions, PSE 5 will do a lossless rotation DS> from the Organizer. To be honest, I do not know exactly DS> what conditions this is not true. I believe it is related DS> to the aspect ratio of the image.

DS> What I do know is this. When PSE can not perform a lossless DS> rotation, it tells you and asks if you want to proceed.

I just did a little experiment with a large jpeg image and PSE 3 (I don’t see much necessity for the later versions). I zoomed in and brought a recognizable part of the image to the center of the screen. I then rotated 17° right. The item moved from the center, which was not unexpected but on rotating 17° left, it did not recenter which one expect if the rotation were truly lossless.

James Silverton
Potomac, Maryland

E-mail, with obvious alterations:
not.jim.silverton.at.verizon.not
JU
jclarke.usenet
Oct 1, 2007
Fishface wrote:
James Silverton wrote:
That is in agreement with what I thought, grids would overlap exactly at 90° intervals but not at *arbitrary* angles. Such rotations are useful but not "lossless" in the general sense.

This lossless jpeg compression does not incur loss from the decompression and re-compression process. Somehow, the
original compression is preserved through the rotation. I use JPEGCrops to occasionally losslessly choose my crop for
printing.

http://ekot.dk/programmer/JPEGCrops/
http://sylvana.net/jpegcrop/

Who said anything about compression? If you rotate an _uncompressed_ image though an arbitrary angle you’ll have some degree of loss due to the need to interpolate pixels of the rotated image that are note exactly mapped to pixels of the source image. 90, 180, and 270 are special cases where the pixels of the rotated image map exactly to pixels of the unrotated image.

—
—
–John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

MacBook Pro 16” Mockups 🔥

– in 4 materials (clay versions included)

– 12 scenes

– 48 MacBook Pro 16″ mockups

– 6000 x 4500 px

Related Discussion Topics

Nice and short text about related topics in discussion sections