sane-project-backends/doc/sane-rts8891.man

.\" .IX sane-rts8891
.TH "sane-rts8891" "5" "16 March 2008" "@PACKAGEVERSION@" "SANE Scanner Access Now Easy"
.SH "NAME"
sane-rts8891 \- SANE backend for Umax Astra 4400/4450 and Hewlett-Packard Scanjet 4470c scanners
.SH "DESCRIPTION"
The
.B sane-rts8891
library implements a SANE (Scanner Access Now Easy) backend that
provides access to scanner based on Realtek RTS8891 ASIC.
.PP 
The scanners that should work with this backend are:
.PP 
.RS
.ft CR
.nf 
   Vendor Model           status
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-  \-\-\-\-\-\-\-\-\-\-\-
  Umax    4400            good
  Umax    4450            untested
  HP      4470c           good                re-badged Astra 4400
.fi 
.ft R
.RE

The options the backend supports can either be selected through
command line options to programs like scanimage or through GUI
elements in xscanimage or xsane.

.br 
If you have any strange behavior, please report to the backend
maintainer or to the SANE mailing list.

Valid command line options and their syntax can be listed by using 
.RS
scanimage --help -d rts8891
.RE

.TP 
.B Scan Mode Options

.TP 
.B --mode
selects the basic mode of operation of the scanner valid choices are 
.I auto
.R ,
.I Color
.R ,
.I Gray
and
.I Lineart
The default or automatic mode is Color. The Lineart mode is black and white only (1 bit). 
Grayscale will produce 256 levels of gray (8 bits). Gray and Lineart mode are emulated.
Color mode allows for over 16 million different colors produced from 24 bits of color information.

.TP 
.B --resolution
selects the resolution for a scan. The horizontal and vertical resolutions are set 
by the value of this option. Default value is 150 dpi, automatic value is 75 dpi.
The scanner is capable of the following resolutions for the specified option value:
.PP 
.RS
.ft CR
.nf 
  Value   Hor. Resolution  Vert. Resolution 
  \-\-\-\-\-   \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-  \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
  75      75dpi            150dpi lines are averaged to match dpi
  150     150dpi           150dpi
  300     300dpi           300dpi
  600     600dpi           600dpi
  1200    1200dpi          600dpi lines are duplicated to match dpi
.fi 
.ft R
.RE

.TP 
.B --preview
requests a preview scan. The resolution used for that scan is 75 dpi
and the scan area and the scan mode are as specified through their options, 
or the default if not specified. The default and automatic value for preview mode is "no".

.TP 
.B Image Enhancement Options

.TP 
.B --threshold
selects the  minimum-brightness to get a white point. The threshold is only used with Lineart mode scans.
It is specified as a percentage in the range 0..100% (in steps of 1).  
The default or automatic value of the threshold option is 50.

.TP
.B --custom-gamma 
allows the user to specify a gamma table (see gamma-table options). The default and automatic
value is 'no'.

.TP 
.B --gamma-table 
(gray and lineart modes) can be used to download a user defined
gamma table for the gray channel. The table must be 256 SANE_Word long.
Valid values are in the [0..255] range. 
The automatic or default value is a builtin gamma table. This option
is active only if custom-gamma is set to yes.

.TP 
.B --red-gamma-table 
(color mode only) can be used to download a user defined
gamma table for the red channel. The table must be 256 SANE_Word long. 
Valid values are in the [0..255] range. 
The automatic or default value is a builtin gamma table. This option
is active only if custom-gamma is set to yes.

.TP 
.B --green-gamma-table 
(color mode only) can be used to download a user defined
gamma table for the green channel. The table must be 256 SANE_Word long.
Valid values are in the [0..255] range. 
The automatic or default value is a builtin gamma table. This option
is active only if custom-gamma is set to yes.

.TP
.B --blue-gamma-table 
(color mode only) can be used to download a user defined gamma table
for the blue channel. The table must be 256 SANE_Word long.
Valid values are in the [0..255] range. 
The automatic or default value is a builtin gamma table. This option
is active only if custom-gamma is set to yes.

.TP 
.B Utility Options

.TP
.B --lamp-on
this advanced option switches the lamp on. It is a set only option.

.TP
.B --lamp-off
this advanced option switches the lamp off. It is a set only option.

.SH "CONFIGURATION FILE"
The configuration file @CONFIGDIR@/rts8891.conf contains only the usb device id (eg usb 0x043d 0x007c).


.SH "FILES"
.TP 
.I @LIBDIR@/libsane-rts8891.a
The static library implementing this backend.
.TP 
.I @LIBDIR@/libsane-rts8891.so
The shared library implementing this backend (present on systems that
support dynamic loading).


.SH "ENVIRONMENT"
.TP 
.B SANE_DEBUG_RTS88XX_LIB
rts88xx library debugging messages control.
.TP
.B SANE_DEBUG_RTS8891_LOW
rts8891 low-level access debugging messages control.
.TP
.B SANE_DEBUG_RTS8891
rts8891 backend debugging messages control.
.br
.br
If the library or backend was compiled with debug support enabled, these
environment variables controls the debug level for this backend. E.g.,
a value of 255 requests all debug output to be printed. Smaller levels
reduce verbosity. Higher levels of debugging also gives PNM files holding
data scanned at various stages of calibration and during final scan. In case
you find a bug and want ot report about it, it is recommended to reproduce
the bug whit these values set to 255, and join the debugging output to the
report.


.SH "LIMITATIONS"
There is no support for transparency adaptor.

.SH "BUGS"
.br 
No bugs are currently known. In case you find a bug, you may report it to the maintainer,
the sane-devel mailing list or fill a bug report at 
https://alioth.debian.org/tracker/?atid=410366&group_id=30186&func=browse


.SH "SEE ALSO"
sane-usb(5), scanimage(1), xscanimage(1), xsane(1), sane(7)


.SH "AUTHOR"
.TP 
This backend is currently developped by St<53>phane Voltz.
.I http://stef.dev.free.fr/sane/rts8891
.SH "CREDITS"
.TP 
Many thanks go to:
Laurent Fournier who lent me his scanjet 4470c.
Henry Wieland for the time spent recording USB activity and testing the experimental version.
The ASIC registers analysis by Troy Rollo and Johannes Hub did provide me of some important
hints on the operation of the RTS8891.