Using Scanners in Fedora Core Linux

You can also use many types of image scanners with The GIMP. In the recent past, the most capable scanners required a SCSI port. Today, however, many scanners work through a USB port. You must have scanner-support enabled for Linux (usually through a loaded kernel module, scanner.o) before using a scanner with The GIMP.

Although some scanners can work via the command line, you will enjoy more productive scanning sessions using a graphical interface because image manipulation tasks, such as previewing and cropping, can save time before actually scanning an image. Most scanners in use with Linux use the Scanner Access Now Easy (SANE) package that supports and enables graphical scanning sessions.

SANE consists of two software components. A low-level driver enables the hardware support and is specific to each scanner. Next, a graphical scanner interface X client known as xsane is used as a plug-in, or ancillary program (or script) that adds features to The GIMP.

NOTE

Although xsane is commonly used as a GIMP plug-in, it can also be used as a standalone program. Another useful program is Joerg Schulenburg's gocr client, used for optical character recognition (OCR). Although not a standalone application, it is included in the Kooka scanning application. This program works best with 300 dots per inch (dpi) scans in several different graphics formats. OCR is a resource-intensive task and can require hundreds of megabytes of disk storage!

A list of currently supported scanners can be found at http://www.sane-project.org/sane-supported-devices.html. Unfortunately, if your scanner doesn't appear on the list, you should not expect it to work with the SANE software. There is also a list on that same page for drivers not yet included, but you must be able to compile the application from source to use them.

Supported USB scanners are automatically detected and the appropriate driver is loaded automatically. The USB devices "tell" the USB system several pieces of information when they are connected the most important of which is the vendor ID and the device ID. This identification is used to look up the device in a table and load the appropriate driver.

Many scanners are supported in Linux. If yours is not, it still might be possible to use it. The Kooka and Xsane scanner applications are included with Fedora Core Linux, and are covered in detail in Chapter 9, "Productivity Applications." They can be found in the Graphics menu as the Scanning and Scan & OCR Program menu items.

USB Scanner Success Is Elusive

Because a failure is sometimes more educational than a success, for previous editions of this book, we attempted to configure a USB scanner that wasn't supported: the Canon N650U. With the release of the version of SANE included with Fedora, the scanner is now supported, and it is automatically detected!

However, here are the manual steps we used for detecting and configuring this scanner in Linux when it did not work properly:

First, connect the scanner. For this USB scanner, look at the output of:

 # cat /proc/bus/usb/devices/ 

(We have truncated the output here to show only the scanner. You can also use the lsusb command.)

 T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=12  MxCh=  D:  Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1 P:  Vendor=04a9 ProdID=2206 Rev= 1.00 S:  Manufacturer=Canon S:  Product=CanoScan C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=500mA I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=(none) E:  Ad=81(I) Atr=03(Int.) MxPS=   1 Ivl=16ms E:  Ad=82(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms E:  Ad=03(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms 

Driver=(none) at the end of the seventh line tells us that the device was not found in the lookup table. Because we now have the "magic" vendor ID and device ID, we can attempt to load the driver manually with

 # /sbin/modprobe scanner vendor=0x04a9 product=0x2206 

Now the output of the catlsusb command from before tells us that the scanner device driver is associated with our scanner:

 I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff  Driver=usbscanner 

and the Kooka and Xsane applications now recognize the scanner.