Auto rotation of potrait(vertical) photos by camera


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#4
You are referring to the auto rotation in the LCD playback of your camera right?

There is no way the actual image quality will be compromised. What your friends may mean is that because the camera auto rotates the photo taken, the resolution of the photo seen in the playback is actually lower and you may not be able to see clearly any flaws that may have had happened on your LCD screen.
 

sethkoo

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Jan 28, 2007
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#5
I am a bit worried, cos I heard from my friends very long ago that if it is jpeg photo, it will cause the quality of the photo to decrease.
I am not sure about camera's auto rotate function will decrease the quality.

But I know that if you rotate in the windows XP's photo viewer, it will definitely decrease the quality....
 

Yatlapball

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May 13, 2006
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#6
I always thought the cambridgecolour website was a very good resource.

Henessy: I think its either you heard wrongly...or your friends do not know what they are talking about. 90 degree rotations are lossless.

Read the section on "Image Rotation Example": http://www.cambridgeincolour.com/tutorials/image-interpolation.htm
 

Henessy

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#7
I always thought the cambridgecolour website was a very good resource.

Henessy: I think its either you heard wrongly...or your friends do not know what they are talking about. 90 degree rotations are lossless.

Read the section on "Image Rotation Example": http://www.cambridgeincolour.com/tutorials/image-interpolation.htm
Thanks a lot. I think I have heard wrongly. Maybe what he means is rotating the picture in windows.
 

zerartul

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#11
I dont think it will reduce the quality in anyway when you rotate in the photo viewer in windows. Rotation if its 90 degrees is just how the picture is being aligned. However if you rotate in software like photoshop and all and in rotations of say 5-10 degrees, there is some but pretty insignificant quality lost due to recalulation of the pixels.
 

Henessy

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#12
I dont think it will reduce the quality in anyway when you rotate in the photo viewer in windows. Rotation if its 90 degrees is just how the picture is being aligned. However if you rotate in software like photoshop and all and in rotations of say 5-10 degrees, there is some but pretty insignificant quality lost due to recalulation of the pixels.
For all formats or just Jpeg only?
 

ah.zeep

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Jun 20, 2006
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#13
Losing quality after rotation is usually more applicable for lossy compression formats, like JPEG. In fact, it's not related to rotation: if you open a JPEG file, and perform any editing to it, and save it back as a JPEG file -- there will be image quality loss.

This is due to the compression used when saving the JPEG image. The only way to minimize loss while saving is to ensure that the compression factor when saving is exactly the same as when it was originally saved - and unfortunately you might not know what it was when first saved.

However, the way JPEG was designed, it is possible to perform 90-degree rotations, and I think 180 degrees as well, without any loss in quality subject to certain size restrictions (e.g. width and height must be divisible by 16 or something like that). In this scenario, the actual image data is not touched at all, but some internal data structures are changed to effect the rotation, so compression factor is not compromised.

So to answer the question: yes with JPEG, see above; other formats like TIFF and RAW, being most likely lossless compression formats, will probably not suffer quality degradation after rotation.
 

catchlights

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#14
IIRC, the rotation of images by camera does not really rotate the images, it only embed a code to the tell the computer softwares like PS or any viewing programe how is this image orientation like. so shouldn't take any effect of quality on the images.

some programme have lossless rotation function also by editing the "code", since it does not open the images, rotate it and save, so it called lossless.
 

Henessy

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#15
IIRC, the rotation of images by camera does not really rotate the images, it only embed a code to the tell the computer softwares like PS or any viewing programe how is this image orientation like. so shouldn't take any effect of quality on the images.

some programme have lossless rotation function also by editing the "code", since it does not open the images, rotate it and save, so it called lossless.
Ok, thanks :D
 

crusher

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Mar 4, 2005
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#16
I know the old ACDSee classic and the Irfanview can do lossless rotation.
 

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