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Author Topic: JPEG Rotation Method Problem  (Read 2878 times)

GHammer

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JPEG Rotation Method Problem
« on: July 27, 2006, 03:01:25 pm »

I believe that v12 rotates jpeg images by changing the EXIF info.
I use a tool to create slideshows that has a problem with this method. The resulting slide images are off color with all images that have been rotated by MC 12.

Not a problem with MC, but if you use other tools to create websites, albums, etc you may want to test this before rotating many images.


More Info
The last 3 posts deal with this problem.
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Matt

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Re: JPEG Rotation Method Problem
« Reply #1 on: July 27, 2006, 06:37:12 pm »

MC 11 and MC 12 losslessly rotate JPEGs but leave the EXIF information unchanged.

MC 12 looks at EXIF information and rotates at display time. (leaving the file unchanged)

This is a tricky area because there's no universal standard. (i.e. honor EXIF, update EXIF on rotate, etc.)
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Matt Ashland, JRiver Media Center

GHammer

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Re: JPEG Rotation Method Problem
« Reply #2 on: July 28, 2006, 09:33:14 am »

Hmmm, I just copied an original (untouched) file to my MC test folder.
Opened MC, waited for Otto to do his thing.
The thumbnail at this time is accurate, it shows the picture needs rotated to the proper aspect.
I opened the format info window and did a capture:


Then I right clicked and rotated it.
Here's a capture of the format info afterwards:


The height/width info has sure enough changed and it shows changed in other tools as well.
If MC is not supposed to change the file then its a bug.
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Matt

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Re: JPEG Rotation Method Problem
« Reply #3 on: July 28, 2006, 10:06:44 am »

"Rotate" losslessly rotates the actual JPEG file.

The database field "Orientation" is used at display time, and filled from EXIF.
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Matt Ashland, JRiver Media Center

marko

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Re: JPEG Rotation Method Problem
« Reply #4 on: August 06, 2006, 09:56:38 am »

I'm still having rotation problems here...
All new files aquired by MC12 are behaving as expected. As far as I can tell, all the problem files are files that were previously rotated by v11.1

Those files are all in need of a 'rotate left' to get them the right way up in MC12, which on the surface, appears to do the job. However, although acdsee displays the image the correct way round, it also displays a little icon, which when clicked on, offers this prompt:


And when the image is shown in the action window, it's shown the wrong way, rotated 90 degrees to the left, which is presumably caused by the previous action to correct the orientation in the filelist.
confused? well, not really, I think I follow what's happening, but do not understand the why's and wherefore's.
really, I just need to know...
a) how to identify the problem files
and
b) how to fix things once and for all.

cheers,
-marko.

marko

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Re: JPEG Rotation Method Problem
« Reply #5 on: August 09, 2006, 04:25:49 pm »

no thoughts on this?

I can't help thinking that if anyone's been using older versions for their images for any length of time, this could become a potential FAQ as v12 rotates all their already rotated images a further 90 degrees around.

Also, to my mind, the fact that the file list is correctly orientating pictures, while the AW is not, to be a bug.

marko

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Re: JPEG Rotation Method Problem
« Reply #6 on: August 10, 2006, 04:16:50 pm »

Quote
16. NEW: When doing a lossless rotation of an image, the EXIF orientation flag and database field for rotation is cleared.

does this have any relevance to my last two posts here?

If it does, what of files previously rotated. Will an 'update tags' sort them out?

Matt

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Re: JPEG Rotation Method Problem
« Reply #7 on: August 10, 2006, 04:27:29 pm »

does this have any relevance to my last two posts here?

If it does, what of files previously rotated. Will an 'update tags' sort them out?

Previously rotated files may show with the wrong orientation after a fresh import with MC 12.

Simply use the lossless "Rotate Left" or "Rotate Right" until they're right-way up.

Since rotation sets the EXIF orientation to "Normal", there's no chance of any program (MC included) rotating them further at display time.
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marko

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Re: JPEG Rotation Method Problem
« Reply #8 on: August 10, 2006, 05:10:40 pm »

OK, Thanks.
I *think* I understand... I'll be back with another 'blonde' post if I'm still not getting it :)
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