Asked By Alain M. Dube
05-Nov-09 02:15 PM

Hello;
I have got some image handling code that has been working for years under
Windows XP and Windows Vista. The code rotates a JPEG image and its
embedded EXIF thumbnail. The code uses an encoder transformation
(EncoderValueTransformRotate90) to perform the image rotation. When the
image height and width are multiples of 16, a lossless rotate is performed
by GDI+. When the height and/or width of the image to be rotated is not a
multiple of 16, a lossy rotate is performed.
Rotating a JPEG image also results in the embedded EXIF thumbnail being
rotated. However, when run under Windows 7, a lossy image rotation fails to
rotate the embedded EXIF thumbnail. Note that lossless rotations work
correctly, for both the image and the embedded thumbnail. Also, both
lossless and lossy rotations work correctly when run under XP and Vista.
Is there a recommended technique for GDI+ JPEG image rotation that rotates
both the image and the embedded EXIF thumbnail and runs correctly on all
platforms? Or, is there a workaround for this operation on Windows 7?
Thanks in advance;
Alain