Changes in Plustek SANE-backend for dark scans

diff --git "a/diff/old/plustek-usb.c" "b/diff/new/plustek-usb.c"
index 6c9e67a..133837f 100644
--- "a/diff/old/plustek-usb.c"
+++ "b/diff/new/plustek-usb.c"
@@ -1366,6 +1366,12 @@ usbDev_Prepare( Plustek_Device *dev, SANE_Byte *buf )
                  scan->sParam.UserDpi.y, scan->sParam.PhyDpi.y, scan->wSumY );
            }
        }
+
+       /* Switch lamp off for dark scan ? */
+       if (dev->adj.dark_scan != 0) {
+           DBG( _DBG_INFO, "Dark-Scan: switching lamps off..\n" );
+           usb_LampOn( dev, SANE_FALSE, SANE_TRUE );
+       }
    }

    dumpPicInit( &scan->sParam, "plustek-pic.raw" );
diff --git "a/diff/old/plustek.c" "b/diff/new/plustek.c"
index a8debeb..a270ed4 100644
--- "a/diff/old/plustek.c"
+++ "b/diff/new/plustek.c"
@@ -248,6 +248,7 @@ static const SANE_Range warmup_range   = { -1,   999, 1 };
 static const SANE_Range offtimer_range = {  0,   999, 1 };
 static const SANE_Range gain_range     = { -1,    63, 1 };
 static const SANE_Range loff_range     = { -1, 16363, 1 };
+static const SANE_Range darkscan_range = {  0,     1, 1 };

 /* authorization stuff */
 static SANE_Auth_Callback auth = NULL;
@@ -303,6 +304,7 @@ static void show_cnf( CnfDef *cnf )
    DBG( _DBG_SANE_INIT,"green Gamma  : %.2f\n",cnf->adj.ggamma              );
    DBG( _DBG_SANE_INIT,"blue Gamma   : %.2f\n",cnf->adj.bgamma              );
    DBG( _DBG_SANE_INIT,"gray Gamma   : %.2f\n",cnf->adj.graygamma           );
+   DBG( _DBG_SANE_INIT,"dark scan    : %d\n",  cnf->adj.dark_scan           );
    DBG( _DBG_SANE_INIT,"---------------------\n" );
 }

@@ -1109,6 +1111,16 @@ init_options( Plustek_Scanner *s )
    }

    usb_UpdateButtonStatus( s );
+
+   /* scan dark image without lamps ? */
+   s->opt[OPT_DARK_SCAN].name  = "dark-scan";
+   s->opt[OPT_DARK_SCAN].title = SANE_I18N("Dark Scan");;
+   s->opt[OPT_DARK_SCAN].desc  = SANE_I18N("Perform a dark scan (1) or with the lamps on (0)");
+   s->opt[OPT_DARK_SCAN].type  = SANE_TYPE_INT;
+   s->opt[OPT_DARK_SCAN].constraint_type = SANE_CONSTRAINT_RANGE;
+   s->opt[OPT_DARK_SCAN].constraint.range = &darkscan_range;
+   s->val[OPT_DARK_SCAN].w     = adj->dark_scan;
+
    return SANE_STATUS_GOOD;
 }

@@ -1427,6 +1439,8 @@ init_config_struct( CnfDef *cnf )
    cnf->adj.rgamma    = 1.0;
    cnf->adj.ggamma    = 1.0;
    cnf->adj.bgamma    = 1.0;
+
+   cnf->adj.dark_scan = 0;
 }

 /** intialize the backend
@@ -1546,6 +1560,8 @@ sane_init( SANE_Int *version_code, SANE_Auth_Callback authorize )
            decodeVal( str, "redGamma",   _FLOAT, &config.adj.rgamma, &dval );
            decodeVal( str, "greenGamma", _FLOAT, &config.adj.ggamma, &dval );
            decodeVal( str, "blueGamma",  _FLOAT, &config.adj.bgamma, &dval );
+
+           decodeVal( str, "dark_scan", _INT, &config.adj.dark_scan, &ival);
            continue;

        /* check for sections: */
@@ -1958,6 +1974,13 @@ sane_control_option( SANE_Handle handle, SANE_Int option,
                DBG( _DBG_INFO, "Reading BLUE gamma.\n" );
                memcpy( value, s->val[option].wa, s->opt[option].size );
                break;
+
+           /* dark scan */
+           case OPT_DARK_SCAN:
+               DBG( _DBG_INFO, "Reading drak_scan.\n" );
+               *(SANE_Word *)value = s->val[OPT_DARK_SCAN].w;
+               break;
+
            default:
                return SANE_STATUS_INVAL;
        }
@@ -2017,6 +2040,12 @@ sane_control_option( SANE_Handle handle, SANE_Int option,
                    if( NULL != info )
                        *info |= SANE_INFO_RELOAD_PARAMS;
                    break;
+               case OPT_DARK_SCAN:
+                   DBG( _DBG_INFO, "Setting dark_scan to 0x%02x.\n", *(SANE_Word *)value);
+                   s->val[option].w = *(SANE_Word *)value;
+                   if( NULL != info )
+                       *info |= SANE_INFO_RELOAD_PARAMS;
+                   break;

                case OPT_CACHECAL:
                    s->val[option].w = *(SANE_Word *)value;
@@ -2527,6 +2556,9 @@ local_sane_start(Plustek_Scanner *s, int scanmode )

    tsecs = 0; /* reset timer */

+   DBG( _DBG_INFO, "--- dark_scan is set to 0x%02x, transfer to dev...\n", s->val[OPT_DARK_SCAN].w);
+   dev->adj.dark_scan = s->val[OPT_DARK_SCAN].w;
+
    result = usbDev_startScan( dev );
    if( result < 0 ) {
        DBG( _DBG_ERROR, "usbDev_startScan() failed(%d)\n", result );
@@ -2581,6 +2613,7 @@ sane_start( SANE_Handle handle )
    int              fds[2];

    DBG( _DBG_SANE_INIT, "sane_start\n" );
+   DBG( _DBG_INFO, "--- dark_scan is set to 0x%02x.\n", s->val[OPT_DARK_SCAN].w);

    if (s->scanning)
        return SANE_STATUS_DEVICE_BUSY;
diff --git "a/diff/old/plustek.conf.in" "b/diff/new/plustek.conf.in"
index e16823e..8ba4fce 100644
--- "a/diff/old/plustek.conf.in"
+++ "b/diff/new/plustek.conf.in"
@@ -173,6 +173,11 @@ option enableTPA 0
 option mov 0

 #
+# switch lamps off when scanning. Suitable for scanning B/W negatives or when using as scanner camera
+#
+option dark_scan 0
+
+#
 # and of course the device-name
 #
 # device /dev/usbscanner
diff --git "a/diff/old/plustek.h" "b/diff/new/plustek.h"
index be657c1..0244916 100644
--- "a/diff/old/plustek.h"
+++ "b/diff/new/plustek.h"
@@ -247,6 +247,7 @@ enum {
    OPT_BUTTON_3,
    OPT_BUTTON_4,
    OPT_BUTTON_LAST = OPT_BUTTON_4,
+   OPT_DARK_SCAN,
    NUM_OPTIONS
 };

@@ -303,6 +304,9 @@ typedef struct {

    double  graygamma;

+   /* scan without lamps */
+   int dark_scan;
+
 } AdjDef;

 typedef struct {