Olympus C-4000

gphoto2 --manual describes how to switch camera control mode.

When camera control is off, modprobe sd-mod; modprobe usb-storage allows the camera flash to be mounted in the filesystem, often from the device /dev/sda1

When camera control is on, gphoto2 can be used to control the camera more extensively.

gphoto2 --port=usb --capture-image -L
Take a picture, then list pictures in memory.
gphoto2 --port=usb -L
Just list the pictures in memory.
gphoto2 --port=usb --folder=/DCIM/100OLYMP --get-file P1010001.TIF
Download P1010001.TIF

An image from the camera can be used as a template for faking in GIMP. It can then be recombined with a header from the camera's saved tiff's for upload to the camera memory, such that the camera can be used as a portable image viewer.

# image is 9437184 header is 14409
dd if=P1010001.TIF of=P1010002.TIF bs=14409 count=1
dd if=gimp.tif of=P1010002.TIF skip=8 seek=14409 bs=1 count=9437184