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If I wanted to rotate photos in XP using Windows Photo Viewer I was told, that it wasn't lossless rotation (so, worse quality in the rotated photo).

What about Win7 and Windows Photo Viewer? Is it lossless rotation of jpegs in Win7?

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3 Answers

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After a brief experiment here with Windows 7 Pro 32bit - No it isn't lossless.

Use a dedicated image editing program (like GIMP) for almost (see comments below) lossless rotation/editing etc.

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Thanks for performing an experiment! :-) Good to know that it's lossy rotations. Where you warned, when rotating the photo?I personnaly use GIMP for photo-editing and IrfanView to view and rotate photos (lossless). I asked the question, because some family-members like to rotate photos using Windows Photo Viewer (which I from now on will recommend them NOT to do!) ;-) –  SanSaurus Nov 30 '11 at 12:07
    
I use FastStone Image Viewer at home and it supports a lossless JPG rotate feature. I saw the comment saying you use IrfanView, it probably has the capability to do that as well. –  Melikoth Nov 30 '11 at 13:09
    
Nope no warnings, not even an option of leaving the original alone and creating a new, rotated, updated file! –  HaydnWVN Nov 30 '11 at 13:26
    
Could be funny to rotate a nice jpeg photo let say 1000 times using Windows Photo Viewer and then see the result! :-) Will it get worse for each rotation? –  SanSaurus Dec 5 '11 at 15:02
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AFAIK, Gimp does not support lossless rotation (for JPEG files). –  Denilson Sá Mar 13 '12 at 3:21
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Short answer:

If the dimensions of the image are multiples of 8 (or 16 if chroma subsampling is used) then the rotations are lossless. Otherwise it is not possible to rotate the image without recomputing the blocks i.e. recompressing the image, which is lossy.

Full details:

See here for the rest of that great explanation about lossless JPEG rotation and Photo Viewer under Win 7.

I suggest you try Xnview as your image viewer, it has many interesting functions that I particularly like:

  • advanced options for slideshows
  • contact sheets creation from pictures folders
  • supports many more file types than the windows default one
  • quick edit pics by adjusting brightness/contrast/exposure/color
  • multiplatform

Make sure you comply with the licence because Xnview is not free for commercial use.

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Thanks! Good explanation in the link you posted. And thank you for recommending Xnview. I use IrfanView to view and do basic manipulation on photos. Is Xnview open source? –  SanSaurus Nov 30 '11 at 12:10
    
Sure, I highlighted that point in my answer above: "and is opensource," :) –  Shadok Nov 30 '11 at 13:52
    
Heh, my question was related to your last bullet. On the website it says "freeware", but I don't think it's opensource?! –  SanSaurus Dec 5 '11 at 15:01
    
My bad, it's not opensource at all. I just found out after many years using it :/ The licence is too restrictive for my tastes too, commercial use is not free. –  Shadok Dec 5 '11 at 15:31
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I suggest using the GUI-based Jpegcrop Windows program, or one of the many programs based on IJG jpegtran code (although not all of them support cropping).

(This answer was based on this other answer, and also on my answer on a Mac OS X Question.)

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