[TYPO3-dam] Metrics of uploaded JPGs always doubled original size (which is wrong!)

[Gabriel Nock]

Hello,

since I use DAM for my file management I have the problem that uploaded
JPG-files are indexed with the wrong metrics.
They always show doubled sizes (hor. and ver.)

If I upload a JPG image with the original dimensions 100x100px / 150dpi the
metrics fields will contain 200x200px / 150dpi.

The file itself is not resized or anyhow processed since a preview of a
record in the the Media->filelist shows the original image. By inserting it
as "plain image" into the RTE it will be inserted with the doubled
dimensions tho.
Up to now I have to delete/change the metrics entries for every uploaded JPG
to make it usable as a normal "plain image".

This only happens to JPG files and occured already in previous Typo3 version
(4.3,4.4 and now 4.5)

Since I could not find anything on this problem I have no idea where this
could come from and if this could be a bug or just a configuration issue
which I could not find yet.

Did anyone every come across this behaviour or any other idea what could
cause this?

Best
Gabriel