Author Topic: Another Viewer Question - rotation seems backwards? (v.5.6.18)  (Read 895 times)

Panther

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Ok - got another newbie question about the Viewer in 5.6.18 that I can't figure out and am hoping someone here can help me with.  I have a few images that show up in the main iMatch preview pane rotated 90 degrees clockwise (so the image basically looks horizontal, with the top of the document on the right side).  I'd like to get them displayed vertically, with the top of the document at the top. 

In the Viewer, the choice I have to select to make this work is called "Virtually Rotate right by 90 degrees" [emphasis supplied].  Maybe it's just a language thing (are these concepts different in Germany?), but I would expect rotating the image in this case to the right would result in it going clockwise and ending up upside down, but instead it rotates it to the left (counterclockwise) and ends up just fine.  Why?

That was puzzling enough, but as I was reading the Help file to try to figure out whether rotation of the display in the viewer (or the preview pane) would mess up my original file in any way, I ran across the discussion about using the "Commands/Image/Orientation (EXIF)" on the menu to change the metadata to specify the orientation.  That's where it got weirder.  None of the commands seemed to do what I expected them to do (i.e., rotate the image the way the commands said they would).

Is this some odd quirk of EXIF or something where instead of telling it to rotate your image a certain way, you need to tell it in reverse, i.e., you need to tell it that the image is already (incorrectly) rotated a certain way and then iMatch will know to correct it when it displays the image?  In the above example of a file that is displaying as rotated 90 degrees clockwise to begin with, when I picked the command to "rotate 90 degrees CW" it made it display correctly (even though if it had actually rotated the image 90 degrees clockwise it would have been upside down).  So I guess I can work around that, but it sure seems backward/counter-intuitive to have to tell iMatch to do the opposite of what you want it to do in order for it to work correctly.

jch2103

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Re: Another Viewer Question - rotation seems backwards? (v.5.6.18)
« Reply #1 on: April 10, 2016, 06:00:41 AM »
Is this some odd quirk of EXIF or something ... ?

Briefly, yes. It should work, but sometimes things get messed up (by other programs, etc.). See these links, for example:
https://www.photools.com/community/index.php?topic=5287.msg36780#msg36780
and
https://www.photools.com/community/index.php?topic=5105.msg35406#msg35406

Sometimes the solution is to change the Orientation via the Menu Rotate and Transform -> Orientation (Exif) and set to Normal. But try that on a copy first.
John

Mario

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Re: Another Viewer Question - rotation seems backwards? (v.5.6.18)
« Reply #2 on: April 10, 2016, 07:51:33 AM »
Sounds like the image data in your file does not match the EXiF orientation in your file.
If you work with RAW files (you did not mention which file format you use) the orientation of the embedded preview may differ from the RAW data. Or the installed WIC codec has trouble handling the data. Many potential reasons.

Mixing EXIF orientation with virtual rotations in IMatch is never a good idea. Virtual rotation is meant to be used for images which have no EXIF data or which have a wrong orientation but are not writable. These can be fixed by a virtual rotation in IMatch, at leas for display.

The QVP and the Viewer use the same display technology, they should show your files oriented in the same way. They rotate the image in the orientation specified by EXIF. Which is not always intuitive, because of the way EXIF has named the options.

To fix things, start by setting EXIF orientation to neutral via the Commans > Images... command.
Then check how the image is displayed then. This tells you how the pixel data in the file is saved, and which orientation should be in EXIF to make it look right.

ubacher

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Re: Another Viewer Question - rotation seems backwards? (v.5.6.18)
« Reply #3 on: April 10, 2016, 01:19:27 PM »
I had the same confusion as you about the rotate functions and how they work.

Solution is: Make sure exif rotation is reset - as Mario mentioned.
           and: make sure there is no virtual rotation set in Imatch. (An icon on the right show if image is rotated by IM)

And then there is the problem mentioned with FPV - if you use it set it up correctly.

Panther

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Re: Another Viewer Question - rotation seems backwards? (v.5.6.18)
« Reply #4 on: April 10, 2016, 05:30:32 PM »
Thanks for all the replies.  I'll play around with this a bit more and see if it starts to make more sense.

These particular images were taken with my iPhone (hadn't expected to go to the Archives that day or to find these squadron records there, so I didn't have my regular camera with me but couldn't pass up the chance to get these records photographed once I found them).  I don't know what info they do or don't have as I've never really messed with iPhone photos before - all I know is that when I was looking at them in iMatch some of them were rotated sideways (90 degrees clockwise) and thus too hard to read, so I just need some simple way to turn them right-side-up so I can read them to figure out what categories to assign to them.

Carlo Didier

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Re: Another Viewer Question - rotation seems backwards? (v.5.6.18)
« Reply #5 on: April 11, 2016, 07:14:19 PM »
These particular images were taken with my iPhone
My experience with various smartphones is that the sensor which should detect the image orientation doesn't work very reliably, especially if you hold the phone at a flat angle, i.e. looking more or less straight down or up.

Panther

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Re: Another Viewer Question - rotation seems backwards? (v.5.6.18)
« Reply #6 on: April 11, 2016, 08:15:15 PM »
These particular images were taken with my iPhone
My experience with various smartphones is that the sensor which should detect the image orientation doesn't work very reliably, especially if you hold the phone at a flat angle, i.e. looking more or less straight down or up.

That would make sense here - these pics were all taken "flat" from above the docs on the desk at the archives.  Fortunately there were only about 100 of them (I wish I had time to take more but I stumbled onto the records right before closing time), and not all of them were turned weird, so it was pretty easy to get them rotated manually via the command menu in iMatch.