OK, there is a little hole in functionality here, that will explain your experience.
Any storage you add to LinuxMCE will be configured in one of two different options. 1) Using LinuxMCE's folder structure, 2) make all media public. When it first detects your storage, this is one of the questions it asks you .... do you want to use LinuxMCE's folder structure?
Option 1) For general storage that you intend, primarily, to use for LinuxMCE the answer should always be "Use LinuxMCE's folder structure", as this ensures that you can still access all the media using Filename sort mode in the Orbiters even if they have no meta tag information. In this mode, LinuxMCE will create new standard media folders on the storage device, and then expect all media to be placed in the appropriate folder. It ignores everything else on the storage device that isn't in these folders.
Option 2) Setting everything as public scans the entire device and adds all media to the database... BUT... you can only browse this media on the Orbiters if it has had meta tag information added to each of the media files.
With the first option, this won't work very well with memory cards from cameras because they have their own folder structure that they enforce, so the pictures will not be in the correct locations for LinuxMCE to be able to see them, unless you move them, which is hardly ideal! The second option means that the media needs to be tagged ... most mp3 files are already tagged with ID3 tags and LinuxMCE can read those and add them to the database, allowing you to browse them. However, there is currently no equivalent for pictures that LinuxMCE understands. So again, unless you manually tag the files, they will not appear, and this is hardly convenient, either.
For now, the solution is likely to be, just copy the pictures off the memory cards to your normal media shares under the standard folders so that LinuxMCE can browse them. It is unlikely that you wil want to keep them indefinitely on the camera's memory card anyway.
Longer term, I think that the "other" folder, where shares configured as "make all media public" land, should be exposed in the Filename sort mode so that even media not in the LinuxMCE folder structures, can be browsed in the same way. Just an "other" folder, then a folder each under that for each share configured in this way.
Also, I am aware that someone is working on adding meta data scanning for pictures (EXIF?) and adding that data to the database. With an expansion in the types of sort modes, this could well allow another approach to browsing such files.