create flag when sensor is always at full hw resolution

backend/genesys_devices.c

@@ -1468,6 +1468,7 @@ static Genesys_Model canon_4400f_model = {
   GENESYS_FLAG_STAGGERED_LINE |
   GENESYS_FLAG_SKIP_WARMUP |
   GENESYS_FLAG_DARK_CALIBRATION |
+  GENESYS_FLAG_FULL_HWDPI_MODE |
   GENESYS_FLAG_CUSTOM_GAMMA,
   GENESYS_HAS_SCAN_SW | GENESYS_HAS_FILE_SW | GENESYS_HAS_COPY_SW,
   100,

backend/genesys_low.c

@@ -1124,6 +1124,12 @@ sanei_genesys_wait_for_home (Genesys_Device * dev)
  */
 int sanei_genesys_compute_dpihw(Genesys_Device *dev, int xres)
 {
+  /* some scanners use alxways hardware dpi for sensor */
+  if (dev->model->flags & GENESYS_FLAG_FULL_HWDPI_MODE)
+    {
+      return dev->sensor.optical_res;
+    }
+
   /* can't be below 600 dpi */
   if (xres <= 600)
     {

backend/genesys_low.h

@@ -128,6 +128,7 @@
 #define GENESYS_FLAG_SIS_SENSOR       (1 << 16)       /**> handling of multi-segments sensors in software */
 #define GENESYS_FLAG_SHADING_NO_MOVE  (1 << 17)       /**> scanner doesn't move sensor during shading calibration */
 #define GENESYS_FLAG_SHADING_REPARK   (1 << 18)       /**> repark head between shading scans */
+#define GENESYS_FLAG_FULL_HWDPI_MODE  (1 << 19)       /**> scanner always use maximum hw dpi to setup the sensor */
 
 #define GENESYS_HAS_NO_BUTTONS       0              /**> scanner has no supported button */
 #define GENESYS_HAS_SCAN_SW          (1 << 0)       /**> scanner has SCAN button */