$ scanimage -d pnm:0 --help
Usage: scanimage [OPTION]...

Start image acquisition on a scanner device and write PNM image data to
standard output.

-b, --batch=FORMAT         working in batch mode
    --format=pnm|tiff      file format of output file
-d, --device-name=DEVICE   use a given scanner device (e.g. hp:/dev/scanner)
-h, --help                 display this help message and exit
-L, --list-devices         show available scanner devices
-T, --test                 test backend thoroughly
-v, --verbose              give even more status messages
-V, --version              print version information
    --accept-md5-only      only accept authorization requests using md5

Options specific to device `pnm:0':
  Source Selection:
    --filename <string> [/tmp/input.ppm]
        The filename of the image to be loaded.
  Image Enhancement:
    --brightness -100..100% [0]
        Controls the brightness of the acquired image.
    --contrast -100..100% [0]
        Controls the contrast of the acquired image.
    --grayify[=(yes|no)] [no]
        Load the image as grayscale.
    --three-pass[=(yes|no)] [no]
        Simulate a three-pass scanner by returning 3 separate frames.  For
        kicks, it returns green, then blue, then red.
    --hand-scanner[=(yes|no)] [no]
        Simulate a hand-scanner.  Hand-scanners often do not know the image
        height a priori.  Instead, they return a height of -1.  Setting this
        option allows to test whether a frontend can handle this correctly.
    --default-enhancements
        Set default values for enhancement controls (brightness & contrast).

Type ``scanimage --help -d DEVICE'' to get list of all options for DEVICE.

List of available devices:
    pnm:0 pnm:1 epson:/dev/scanner/usb/0
$ scanimage -d pnm:0 --help
Usage: scanimage [OPTION]...

Start image acquisition on a scanner device and write PNM image data to
standard output.

-b, --batch=FORMAT         working in batch mode
    --format=pnm|tiff      file format of output file
-d, --device-name=DEVICE   use a given scanner device (e.g. hp:/dev/scanner)
-h, --help                 display this help message and exit
-L, --list-devices         show available scanner devices
-T, --test                 test backend thoroughly
-v, --verbose              give even more status messages
-V, --version              print version information
    --accept-md5-only      only accept authorization requests using md5

Options specific to device `pnm:0':
  Source Selection:
    --filename <string> [/tmp/input.ppm]
        The filename of the image to be loaded.
  Image Enhancement:
    --brightness -100..100% [0]
        Controls the brightness of the acquired image.
    --contrast -100..100% [0]
        Controls the contrast of the acquired image.
    --grayify[=(yes|no)] [no]
        Load the image as grayscale.
    --three-pass[=(yes|no)] [no]
        Simulate a three-pass scanner by returning 3 separate frames.  For
        kicks, it returns green, then blue, then red.
    --hand-scanner[=(yes|no)] [no]
        Simulate a hand-scanner.  Hand-scanners often do not know the image
        height a priori.  Instead, they return a height of -1.  Setting this
        option allows to test whether a frontend can handle this correctly.
    --default-enhancements
        Set default values for enhancement controls (brightness & contrast).

Type ``scanimage --help -d DEVICE'' to get list of all options for DEVICE.

List of available devices:
    pnm:0 pnm:1 epson:/dev/scanner/usb/0
