RGB->Gray C and Py API2.0 (#15050)

* Add RGB to GRAY to C API 2.0

* Add RGB to GRAY to Py API 2.0

* ClangFormat + PyFlake8

src/bindings/c/docs/api_overview.md

@@ -207,6 +207,8 @@ enum colorformat_e {
 
 ​    BGR,         ///< BGR color format, default in OpenVINO
 
+​    GRAY,        ///< GRAY color format
+
 ​    RGBX,        ///< RGBX color format with X ignored during inference
 
 ​    BGRX,        ///< BGRX color format with X ignored during inference

src/bindings/c/include/openvino/c/ov_prepostprocess.h

@@ -77,6 +77,7 @@ typedef enum {
     I420_THREE_PLANES,  //!< Image in I420 format represented as separate tensors for Y, U and V planes.
     RGB,                //!< Image in RGB interleaved format (3 channels)
     BGR,                //!< Image in BGR interleaved format (3 channels)
+    GRAY,               //!< Image in GRAY format (1 channel)
     RGBX,               //!< Image in RGBX interleaved format (4 channels)
     BGRX                //!< Image in BGRX interleaved format (4 channels)
 } ov_color_format_e;

src/bindings/c/src/ov_prepostprocess.cpp

@@ -18,6 +18,7 @@ const std::map<ov_color_format_e, ov::preprocess::ColorFormat> color_format_map
     {ov_color_format_e::I420_THREE_PLANES, ov::preprocess::ColorFormat::I420_THREE_PLANES},
     {ov_color_format_e::RGB, ov::preprocess::ColorFormat::RGB},
     {ov_color_format_e::BGR, ov::preprocess::ColorFormat::BGR},
+    {ov_color_format_e::GRAY, ov::preprocess::ColorFormat::GRAY},
     {ov_color_format_e::RGBX, ov::preprocess::ColorFormat::RGBX},
     {ov_color_format_e::BGRX, ov::preprocess::ColorFormat::BGRX}};
 

src/bindings/c/tests/ov_preprocess_test.cpp

@@ -301,6 +301,23 @@ TEST_F(ov_preprocess, ov_preprocess_preprocess_steps_convert_color) {
     OV_EXPECT_OK(ov_preprocess_preprocess_steps_convert_color(input_process, ov_color_format_e::BGR));
 }
 
+TEST_F(ov_preprocess, ov_preprocess_preprocess_steps_convert_color_rgb_to_gray) {
+    OV_EXPECT_OK(ov_preprocess_prepostprocessor_create(model, &preprocess));
+    EXPECT_NE(nullptr, preprocess);
+
+    OV_EXPECT_OK(ov_preprocess_prepostprocessor_get_input_info_by_index(preprocess, 0, &input_info));
+    EXPECT_NE(nullptr, input_info);
+
+    OV_EXPECT_OK(ov_preprocess_input_info_get_preprocess_steps(input_info, &input_process));
+    EXPECT_NE(nullptr, input_process);
+
+    OV_EXPECT_OK(ov_preprocess_input_info_get_tensor_info(input_info, &input_tensor_info));
+    EXPECT_NE(nullptr, input_tensor_info);
+
+    OV_EXPECT_OK(ov_preprocess_input_tensor_info_set_color_format(input_tensor_info, ov_color_format_e::RGB));
+    OV_EXPECT_OK(ov_preprocess_preprocess_steps_convert_color(input_process, ov_color_format_e::GRAY));
+}
+
 TEST_F(ov_preprocess, ov_preprocess_prepostprocessor_get_output_info) {
     OV_EXPECT_OK(ov_preprocess_prepostprocessor_create(model, &preprocess));
     EXPECT_NE(nullptr, preprocess);

src/bindings/python/src/pyopenvino/graph/preprocess/pre_post_process.cpp

@@ -453,6 +453,7 @@ static void regenum_graph_ColorFormat(py::module m) {
         .value("I420_THREE_PLANES", ov::preprocess::ColorFormat::I420_THREE_PLANES)
         .value("RGB", ov::preprocess::ColorFormat::RGB)
         .value("BGR", ov::preprocess::ColorFormat::BGR)
+        .value("GRAY", ov::preprocess::ColorFormat::GRAY)
         .value("RGBX", ov::preprocess::ColorFormat::RGBX)
         .value("BGRX", ov::preprocess::ColorFormat::BGRX)
         .export_values();

src/bindings/python/tests/test_graph/test_preprocess.py

@@ -401,6 +401,28 @@ def test_graph_preprocess_steps(algorithm, color_format1, color_format2, is_fail
             assert op in model_operators
 
 
+@pytest.mark.parametrize(
+    ("color_format1", "color_format2", "tensor_in_shape", "model_in_shape"),
+    [(ColorFormat.RGB, ColorFormat.GRAY, [1, 3, 3, 3], [1, 3, 3, 1]),
+     (ColorFormat.BGR, ColorFormat.GRAY, [1, 3, 3, 3], [1, 3, 3, 1]),
+     ])
+def test_graph_preprocess_convert_color(color_format1, color_format2, tensor_in_shape, model_in_shape):
+    parameter_a = ops.parameter(model_in_shape, dtype=np.float32, name="A")
+    model = parameter_a
+    function = Model(model, [parameter_a], "TestFunction")
+
+    custom_processor = PrePostProcessor(function)
+    inp = custom_processor.input()
+    inp.tensor().set_color_format(color_format1)
+    inp.preprocess().convert_color(color_format2)
+    function = custom_processor.build()
+
+    assert function.get_output_size() == 1
+    assert list(function.inputs[0].shape) == tensor_in_shape
+    assert list(function.get_output_shape(0)) == model_in_shape
+    assert function.get_output_element_type(0) == Type.f32
+
+
 def test_graph_preprocess_postprocess_layout():
     shape = [1, 1, 3, 3]
     parameter_a = ops.parameter(shape, dtype=np.float32, name="A")