[digikam] [Bug 344155] New: Rotating raw image sometimes results in the preview showing the photo rotated in the opposite direction

[DrSlony-4]

https://bugs.kde.org/show_bug.cgi?id=344155

            Bug ID: 344155
           Summary: Rotating raw image sometimes results in the preview
                    showing the photo rotated in the opposite direction
           Product: digikam
           Version: 4.7.0
          Platform: Gentoo Packages
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: Preview
          Assignee: [hidden email]
          Reporter: [hidden email]

See bug 344154. Sometimes I rotate a bunch of photos left 90 degrees, then when
I preview them, some of them are rotated 90 degrees right.

Now I set Configure > Album View > Preview Options > "Raw data in half size"
You can see the thumbnail rotated right while the preview is rotated left
http://i.imgur.com/U6mosw1.jpg

Reproducible: Sometimes

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[Maik Qualmann]

https://bugs.kde.org/show_bug.cgi?id=344155

Maik Qualmann <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[hidden email]

--- Comment #1 from Maik Qualmann <[hidden email]> ---
Created attachment 91081
  --> https://bugs.kde.org/attachment.cgi?id=91081&action=edit
rawrotation.patch

I put this patch for discussion. Now is the Raw data in half size preview in
sync with the thumbnail. But I'm not 100% sure...

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=344155

Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Rotating raw image          |Rotating raw image
                   |sometimes results in the    |sometimes results in the
                   |preview showing the photo   |preview showing the photo
                   |rotated in the opposite     |rotated in the opposite
                   |direction                   |direction [patch]
                 CC|                            |[hidden email]

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=344155

--- Comment #2 from Gilles Caulier <[hidden email]> ---
Maik,

I'm not sure if your patch is fine about Raw preview rotation support.

Some technical points about RAW :

1/ Raw are mostly TIFF/EP files with private data. RAW are container of data
(images + metadata)
2/ Preview in RAW are typically reduced JPEG generated by camera.
3/ Raw image has dedicated metadata. This include Exif orientaion flag.
4/ Preview Image has dedicated metadata also, with another orientation flag.
5/ When you rotate image in camera (while image review on screen), you change
orientation flag of preview image, NOT RAW orientation flag.

So, if possible to have an non homogeneous orientation flags in RAW files. This
give strange results in digiKam.

I can reproduce the dysfunction with my Sony A77, as explained before.

Gilles

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[Maik Qualmann]

https://bugs.kde.org/show_bug.cgi?id=344155

Maik Qualmann <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #91081|0                           |1
        is obsolete|                            |

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[Maik Qualmann]

https://bugs.kde.org/show_bug.cgi?id=344155

--- Comment #3 from Maik Qualmann <[hidden email]> ---
Created attachment 91206
  --> https://bugs.kde.org/attachment.cgi?id=91206&action=edit
rotationmatrix.patch

The bug is in libkexiv2, matrix variables for rotate90 and rotate270 are
reversed.
Test:
QMatrix m;
m.rotate(90); // m11() == 0, m12() == 1, m21() == -1, m22() == 0
m.rotate(270); // m11() == 0, m12() == -1, m21() == 1, m22() == 0

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=344155

Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Version Fixed In|                            |4.8.0
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED
      Latest Commit|                            |http://commits.kde.org/libk
                   |                            |exiv2/8498b1b0820d4070030f3
                   |                            |118159d8674f0dbd0e4

--- Comment #4 from Gilles Caulier <[hidden email]> ---
Git commit 8498b1b0820d4070030f3118159d8674f0dbd0e4 by Gilles Caulier.
Committed on 22/02/2015 at 07:00.
Pushed by cgilles into branch 'master'.

apply patch #91206 from MAik Qualmann to fix rotation matrix issue in libkexiv2
FIXED-IN: 4.8.0

M  +7    -5    libkexiv2/rotationmatrix.cpp
M  +1    -1    libkexiv2/rotationmatrix.h

http://commits.kde.org/libkexiv2/8498b1b0820d4070030f3118159d8674f0dbd0e4

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=344155

--- Comment #5 from Gilles Caulier <[hidden email]> ---
Git commit 54d7aecc0ff400c9acd4739fb723570352d8238a by Gilles Caulier.
Committed on 22/02/2015 at 07:05.
Pushed by cgilles into branch 'frameworks'.

backport commit #8498b1b0820d4070030f3118159d8674f0dbd0e4 from git/master to
frameworks branch

M  +5    -7    src/rotationmatrix.cpp

http://commits.kde.org/libkexiv2/54d7aecc0ff400c9acd4739fb723570352d8238a

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=344155

--- Comment #6 from Gilles Caulier <[hidden email]> ---
Git commit 5a716d237a6c379c6300df2b1cc8d25b9ccd9773 by Gilles Caulier.
Committed on 22/02/2015 at 07:09.
Pushed by cgilles into branch 'KDE/4.14'.

backport commit #8498b1b0820d4070030f3118159d8674f0dbd0e4 from git/master to
KDE/4.14 branch

M  +4    -4    libkexiv2/rotationmatrix.cpp

http://commits.kde.org/libkexiv2/5a716d237a6c379c6300df2b1cc8d25b9ccd9773

diff --git a/libkexiv2/rotationmatrix.cpp b/libkexiv2/rotationmatrix.cpp
index b96a174..1e4eb6c 100644
--- a/libkexiv2/rotationmatrix.cpp
+++ b/libkexiv2/rotationmatrix.cpp
@@ -65,9 +65,9 @@ namespace KExiv2Iface
    (I did not proof that mathematically, but empirically)

    static const RotationMatrix identity;               //( 1,  0,  0,  1)
-   static const RotationMatrix rotate90;               //( 0, -1,  1,  0)
+   static const RotationMatrix rotate90;               //( 0,  1, -1,  0)
    static const RotationMatrix rotate180;              //(-1,  0,  0, -1)
-   static const RotationMatrix rotate270;              //( 0,  1, -1,  0)
+   static const RotationMatrix rotate270;              //( 0, -1,  1,  0)
    static const RotationMatrix flipHorizontal;         //(-1,  0,  0,  1)
    static const RotationMatrix flipVertical;           //( 1,  0,  0, -1)
    static const RotationMatrix rotate90flipHorizontal; //( 0,  1,  1,  0),
first rotate, then flip
@@ -79,9 +79,9 @@ namespace Matrix
 {

 static const RotationMatrix identity               ( 1,  0,  0,  1);
-static const RotationMatrix rotate90               ( 0, -1,  1,  0);
+static const RotationMatrix rotate90               ( 0,  1, -1,  0);
 static const RotationMatrix rotate180              (-1,  0,  0, -1);
-static const RotationMatrix rotate270              ( 0,  1, -1,  0);
+static const RotationMatrix rotate270              ( 0, -1,  1,  0);
 static const RotationMatrix flipHorizontal         (-1,  0,  0,  1);
 static const RotationMatrix flipVertical           ( 1,  0,  0, -1);
 static const RotationMatrix rotate90flipHorizontal ( 0,  1,  1,  0);

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[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=344155

--- Comment #7 from Marcel Wiesweg <[hidden email]> ---
My comment is about the original problem and the patch from comment 1:

The complexity has already been explained by Gilles. Another component of the
problem is that libraw/dcraw does some intransparent magic of its own and gives
us the data readily rotated. Which means that we never know in how far the
rotation flags that we can read were actually put in use (maybe the information
was taken from some makernotes, or other special knowledge).

Which means that we read a rotation flag via exiv2, and libraw may use another
value.

Second part of the problem is that we support "virtual rotation" for RAWs,
which means that when rotating in digikam, the flag in digikam's db is changed,
but we cannot change the flag in the raw file (because metadata writing to RAWs
is not universally supported, and the complexity of the file formats would make
it difficult to find the right flag for all formats.
That's the intention of the patched code: Normally, digikam's database contains
the exiv2-read rotation value. If we detect that the current code in the
database is different, the user must have applied an operation, and this
operation B is computed from A and C.

One possible solution was if we would read the rotation flag via libraw instead
of exiv2, or see that the two information source gave the same results.
The second problem is that the thumbnail may have a different rotation than the
main data. I dont know, we must with several formats and see for each single
format where the problem lies.

(In addition I put forward - I'm not a mathematician, so please correct my
equations if necessary - that mathematically, the proposal is not correct.
We have A*B = C.
By multiplication from the left with A_inv, we get
<=> A_inv*A*B = A_inv *C
<=> I * B = A_inv * C
<=> B = A_inv * C

Assume the proposed "B=C_inv*A" was correct:
B = C_inv*A
<=> C*B = C*C_inv*A
<=> C*B = A
<=> C*B*B_inv = A*B_inv
<=> C = A*B_inv
which is true only if B=B_inv, or B*B_inv = I, which is not true for rotate90
for example.
)

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[hidden email] changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|Preview-Image               |Preview-RAW

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