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Linux Multimedia Hacks by Kyle Rankin

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Hack #6. Pull Images from a Digital Camera

Get the images from your camera with either standard USB storage device support or gphoto.

So you have a digital camera full of pictures, and you have a Linux machine with the GIMP raring to go, but you need to get the pictures from the camera to the computer under Linux. As this hack illustrates, using your digital camera under Linux is not much of a headache, particularly with newer distributions and newer cameras.

Although there are many ways to categorize digital cameras, when it comes to using them under Linux there are only two categories: cameras that act as USB storage devices and cameras that don't. Generally, newer cameras act like USB storage devices (such as a USB thumb drive) when plugged into a computer, but many older cameras use proprietary communication standards even though they use standard USBs or serial ports. The easiest way to tell which type of camera you have is to plug it into a non-Linux system. If it shows up as a regular hard drive, under Linux you can treat it like a USB storage device. Otherwise you may have to go the gtkam route, which I describe later, in the section, "Non-USB Storage Devices."

USB Storage Devices

Most modern desktop Linux distributions offer automatic management of USB storage devices—just plug in a USB key or other device, and KDE or Gnome will automatically create a new icon on your desktop that you can click to access the device. If you have such a distribution, then using your digital camera is easy: plug in the camera, click on the icon that appears on the desktop, and browse it like you would any other hard drive. You can copy and paste images to your desktop or another folder, and when you are done you can close the window, right-click on the icon, unmount the camera, and unplug it.

If you don't have such a desktop environment, it still isn't too difficult—you just have to go through an extra step or two. In order to mount your camera, you need to determine which SCSI drive Linux has assigned it. To do this, run tail on your /var/log/syslog or /var/log/messages log file as root, and then plug in the device. You should see output something like this:

	# tail -f /var/log/messages
	Jul 19 20:44:36 moses kernel: SCSI device sda: 58605120 512-byte hdwr 
	sectors (30006 MB)
	Jul 19 20:44:36 moses scsi.agent[30251]:      sd_mod: loaded sucessfully 
	(for disk)
	Jul 19 20:44:36 moses kernel: /dev/scsi/host0/bus0/target0/lun0: p1 
	Jul 19 20:44:36 moses kernel: Attached scsi disk sda at scsi0, channel 0, id 
	0, lun 0
	Jul 19 20:49:16 moses kernel: usb 4-1: USB disconnect, address 4
	Jul 19 21:03:26 moses -- MARK --
	Jul 19 21:23:26 moses -- MARK --
	Jul 19 21:35:19 moses kernel: usb 1-1: new full speed USB device using uhci_
	hcd and address 3
	Jul 19 21:35:19 moses kernel: scsi1 : SCSI emulation for USB Mass Storage 
	devices
	Jul 19 21:35:22 moses usb.agent[4679]:      usb-storage: already loaded

In the output you can see that Linux assigned my digital camera the sda device in this line:

	Jul 19 20:44:36 moses kernel: SCSI device sda: 58605120 512-byte hdwr 
	sectors (30006 MB)

To access the files on the camera, I become root, create a mount point under /mnt, and then use the mount command to access it:

	# mkdir /mnt/camera
	# mount -t vfat /dev/sda1 /mnt/camera

Now I can browse to /mnt/camera either in the terminal or with a file manager and copy files from the camera. I specified a filesystem type of vfat because almost all digital camera media (indeed all flash media) are formatted as vfat. When I'm finished, I unmount the drive and unplug it:

	# umount /dev/sda1

Warning

Like with all USB storage devices, remember to unmount the camera before unplugging it from the computer or powering it off. This ensures that all changed files have been completely written to the camera. Unplugging any USB drive while files are being written almost guarantees file damage.

Non-USB Storage Devices

Not all digital cameras operate as generic USB storage devices, even if they have a USB port. This is particularly true of older digital cameras. To use one of these cameras you must use gtkam, digiKam, gphoto2, or another program that uses the libgphoto libraries to provide basic access to the files on your digital camera.

Most major desktop distributions have packages for gtkam and libgphoto so you can use your standard packaging tool to install them. Otherwise download the source from the official gtkam page at http://www.gphoto.org/proj/gtkam and compile it according to the installation instructions.

Before you run gtkam, connect the camera to the computer by the USB or serial port. Then start gtkam through your application menu or type gtkam in a terminal. The main window appears fairly blank by default, and the first step is to click Camera → Add Camera to open a dialog that displays the full list of cameras gtkam supports.

Click Detect for gtkam to probe the USB ports for your camera, or select it from the list of camera models and click OK. You are dropped back to the main window that then presents you with thumbnails of all your photos. gtkam doesn't provide a lot of photo-editing features; basically you can zoom in and out on your photos and select some or all to save for later editing. Once you are finished, be sure to close gtkam before you unplug your digital camera from the computer.

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