[Digikam-users] Incorrect thumbnails for *.CR2 Canon RAW files in the transfer window

Guillaume Castagnino casta at xwing.info
Mon Jul 14 11:35:33 BST 2008

Le lundi 14 juillet 2008, spade2008 a écrit :
> Hi,
> Everything describing the problem is in the subject, but I can add
> that: - digikam version is 0.9.3
> - the camera is Canon 350D
> - *.CR2 files are displayed, not as correct thumbnails, but as
> generic ones. I still can transfer them
> - *.JPG files are correctly displayed as thumbnails in the transfer
> window - *.CR2 files are correctly displayed as thumbnails in the
> albums window, once the transfer is done
> - I tried to add "*.CR2" in the list of "RAW files" in "MIME types",
> because I thought that "*.cr2" that was already there was not enough,
> but the behaviour is not better.


I have the same with my EOS 5D, but it's OK with my EOS 400D since the 
1.1.0 firmware. Before this version, this was the same, thumbnails were 
not displayed.

The change in the 400D firmware that make the thumbnails display is :
> Changes in Version 1.1.0:
>   1. Adds support for the new Media Transfer Protocol (MTP) USB
> protocol. 
>    Adds support for the Media Transfer Protocol (MTP), which has
> greater expandability than the Picture Transfer Protocol (PTP) used
> for communication between the camera and the computer up to now.  

IMHO, there is absolutly no problem here : the PTP protocol used in 
older Canon Camera does not allow to see thumbnails of raw files before 
file transfer => that means, PTP does not allow to extract thumb from 
metadata (that is where the thumbnail come from for RAW files : the 

Such functionnality is enabled by MTP support (or at least extended PTP 
support), which the 350D or 5D have not.

Beware that this part of the transfer is managed by libgphoto, not 
digikam directly. You should have the same "problem" with all programs 
that use libgphoto for PTP transfers. But IMHO no bug here, only a 
protocol limit.


Guillaume Castagnino
    guilc at laposte.net / casta at xwing.info
GnuPG/PGP key : 
Fingerprint : CD52 FE40 9592 BA1E E89D 5FB6 820E 4742 8AF4 68AF

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