genesys: Implement host-side gray support

backend/genesys/enums.h

@@ -526,6 +526,9 @@ enum class ModelFlag : unsigned
     // disable fast feeding mode on this scanner
     DISABLE_FAST_FEEDING = 1 << 14,
 
+    // scan gray scans as color and combine on host side
+    HOST_SIDE_GRAY = 1 << 15,
+
     // the scanner uses multi-segment sensors that must be handled during calibration
     SIS_SENSOR = 1 << 16,
 

backend/genesys/low.cpp

@@ -445,6 +445,10 @@ Image read_unshuffled_image_from_scanner(Genesys_Device* dev, const ScanSession&
         pipeline.push_node<ImagePipelineNodeMergeMonoLinesToColor>(dev->model->line_mode_color_order);
     }
 
+    if (session.use_host_side_gray) {
+        pipeline.push_node<ImagePipelineNodeMergeColorToGray>();
+    }
+
     if (pipeline.get_output_format() == PixelFormat::BGR888) {
         pipeline.push_node<ImagePipelineNodeFormatConvert>(PixelFormat::RGB888);
     }
@@ -954,6 +958,14 @@ void compute_session(const Genesys_Device* dev, ScanSession& s, const Genesys_Se
     s.output_startx = static_cast<unsigned>(
                 static_cast<int>(s.params.startx) + sensor.output_pixel_offset);
 
+    if (has_flag(dev->model->flags, ModelFlag::HOST_SIDE_GRAY) && s.params.channels == 1 &&
+        s.params.color_filter == ColorFilter::NONE)
+    {
+        s.use_host_side_gray = true;
+        s.params.channels = 3;
+        s.params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
+    }
+
     s.stagger_x = sensor.stagger_x;
     s.stagger_y = sensor.stagger_y;
 
@@ -1280,6 +1292,14 @@ ImagePipelineStack build_image_pipeline(const Genesys_Device& dev, const ScanSes
         }
     }
 
+    if (session.use_host_side_gray) {
+        pipeline.push_node<ImagePipelineNodeMergeColorToGray>();
+
+        if (log_image_data) {
+            pipeline.push_node<ImagePipelineNodeDebug>(debug_prefix + "_10_after_nogray.tiff");
+        }
+    }
+
     if (pipeline.get_output_width() != session.params.get_requested_pixels()) {
         pipeline.push_node<ImagePipelineNodeScaleRows>(session.params.get_requested_pixels());
     }

backend/genesys/settings.cpp

@@ -129,7 +129,8 @@ bool ScanSession::operator==(const ScanSession& other) const
         shading_pixel_offset == other.shading_pixel_offset &&
         buffer_size_read == other.buffer_size_read &&
         enable_ledadd == other.enable_ledadd &&
-        use_host_side_calib == other.use_host_side_calib;
+        use_host_side_calib == other.use_host_side_calib &&
+        use_host_side_gray == other.use_host_side_gray;
 }
 
 std::ostream& operator<<(std::ostream& out, const ScanSession& session)
@@ -166,6 +167,7 @@ std::ostream& operator<<(std::ostream& out, const ScanSession& session)
         << "    buffer_size_read: " << session.buffer_size_read << '\n'
         << "    enable_ledadd: " << session.enable_ledadd << '\n'
         << "    use_host_side_calib: " << session.use_host_side_calib << '\n'
+        << "    use_host_side_gray: " << session.use_host_side_gray << '\n'
         << "    params: " << format_indent_braced_list(4, session.params) << '\n'
         << "}";
     return out;

backend/genesys/settings.h

@@ -324,6 +324,9 @@ struct ScanSession {
     // whether calibration should be performed host-side
     bool use_host_side_calib = false;
 
+    // whether gray scanning should be performed host-side (scan as color and merge to gray)
+    bool use_host_side_gray = false;
+
     void assert_computed() const
     {
         if (!computed) {
@@ -375,6 +378,7 @@ void serialize(Stream& str, ScanSession& x)
     serialize(str, x.buffer_size_read);
     serialize(str, x.enable_ledadd);
     serialize(str, x.use_host_side_calib);
+    serialize(str, x.use_host_side_gray);
 }
 
 std::ostream& operator<<(std::ostream& out, const SANE_Parameters& params);