Lossless JPEG image rotation

Dear Ron.

DUKE?
EDU?
True?

NC/PB

Ron Parr said:

Yehuda Katz said:

Benno,

Rotation in multiples of 90 degrees, and mirroring, are lossless in
all software I know about, as it is a simple one-to-one translation
of coordinates.

Click to expand...

Unless the program specifically offers lossless jpeg rotation, you
will incur a loss when you resave.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

Click to expand...

I'm surprised no one else suggested this ... use Michal Kowalski's EXIF VIEWER program. Its my favourite for moving files from my camera to my PC -- and performs lossless rotations. And if I'm not mistaken, its written by someone that used to frequent this STF forum! Its small, simple, but works really well for what its supposed to do. Oh, and the program icon is a Sony F505V.. that should be reason enough to use it.

http://home.pacbell.net/michal_k/exif_v.html

Hello ,

well, I think I have a lot work to do to decide what tool to use ;-)

Once again, thank you all for the great hints!

Cheers,

Benno

Benno said:

But, as I have said, e.g. IrfanView nevertheless seems to produce
image degradation if performing lossless rotation (which saves
automatically the rotated image). So its seems that it's so called
lossless ratation is not really lossless, but generates a slight
image degradation.

Click to expand...

You should note what "lossless JPEG rotation" really means:
It means that it is reversible , i.e. if you reverse the rotation
with same algorithm then you get exactly the same image as
the original.

Lossless JPEG rotation does not mean that the losslessly rotated
(compressed) JPEG file decompresses to exactly the same image
as if you decompress the original and then rotate the bitmap.
The slight differences are due to the JPEG processing steps,
namely roundup errors in the IDCT and color conversion, and
different parameters and/or algorithms in the internal color
upsampling.
Note that most digital cameras (including Sony) produce 2x1
horizontal only subsampled JPEG files, which turn to 1x2
when losslessly rotated by 90 or 270 degrees.
Most decoders use different algorithms for 2x1 and 1x2 upsampling
(including those based on the free IJG library), since 2x1 is much
more common, while 1x2 was virtually non-existent before
introducing the lossless rotation algorithm.
Thus you may get noticeably different results when comparing
the resulting bitmaps.
But the data itself is still lossless , in the sense that you get
exactly the original when reversing the rotation.

BTW, my modified IJG library for Jpegcrop uses more advanced
upsampling techniques with special adaption to all currently used
subsampling parameters (1x1, 1x2, 2x1, 2x2), thus leaving less
differences for display.

For more information and applications regarding EXIF orientation
processing and lossless rotation, see

http://jpegclub.org/exif_orientation.html
http://jpegclub.org/losslessapps.html

Regards
Guido

Except... it's sloooooooooooow. It typically takes around 30 seconds to rotate a single full res image from my F717.

I still use EXIF Viewer though, mainly because it was one of the few (simple) image viewers that respected the orientation info in my F505V pictures. Nowadays, I am using other programs more frequently as the F717 doesn't have an orientation sensor (another big curse to the guy at Sony who made that decision).

Roy.

BunnyBun said:

I'm surprised no one else suggested this ... use Michal Kowalski's
EXIF VIEWER program. Its my favourite for moving files from my
camera to my PC -- and performs lossless rotations.

Click to expand...

There are people who can do the same thing much quicker: I've found a little program called Rota on the Net. Try this address:

http://www.ba.wakwak.com/~tsuruzoh/index-e.html

and see if it works for you!

Johannes

Roy van der Woning said:

I still use EXIF Viewer though, mainly because it was one of the
few (simple) image viewers that respected the orientation info in
my F505V pictures. Nowadays, I am using other programs more
frequently as the F717 doesn't have an orientation sensor (another
big curse to the guy at Sony who made that decision).

Roy.

BunnyBun said:

I'm surprised no one else suggested this ... use Michal Kowalski's
EXIF VIEWER program. Its my favourite for moving files from my
camera to my PC -- and performs lossless rotations.

Click to expand...

Click to expand...

Thanks Johannes, but I'm already using ACDSee, as well as several other tools to handle this task for me.

I'm still looking for a single tool that does it all (and does it well) but I haven't found it yet. So far, ACDSee and CompuPic are about as close as it gets for me.

Roy.

Johannes Czernin said:

There are people who can do the same thing much quicker: I've found
a little program called Rota on the Net. Try this address:

Click to expand...

Windows XP has rotation available from a right-click.

Just right-click on the image to rotate, and you will see the rotate options. I don't know if it is losses or not. Perhaps someone else can verify.

Benno said:

Hi there,

the F-717 can rotate JPEG images inside the camera (I hope
lossless) and re-saves them to the memory stick, but my image
viewing application (IrfanView 3.80) cannot interpret the
orientation flag in the EXIF info correctly and therefore does not
rotate the image automatically during viewing .

Does anybody of you know software that can

a) interpret the orientation flag in the EXIF info correctly and
display the image correctly rotated automatically during viewing

b) perform a really lossless rotation of the JPEG format, if
I save the rotated image in JPEG format to disk (that means the
rotation does not degrade the image in means of additionally added
JPEG artifacts generated during the saving process)?

IrfanView itself has the feature b), but my examination of the
rotated saved JPEG (especially visible in red areas) lead me to the
conclusion, that there is a quality difference of the rotation of
the JPEG in an imaging application (e.g. Photoshop) and then saving
as TIFF compared to the saved JPEG rotated via the lossless
rotation by IrfanView.

Any experience or hints?

Thanks a lot!
--
Benno

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