[test] better spectral curves for testing

tests/CMakeLists.txt

@@ -21,6 +21,8 @@ add_executable (
 	Test_usage_example_core
 	usage_example_core.cpp
     test_utils.cpp
+    test_data_helpers.cpp
+    test_data_helpers.h
 )
 
 target_link_libraries(
@@ -39,13 +41,17 @@ add_test ( NAME Test_usage_example_core COMMAND Test_usage_example_core )
 add_executable (
 	Test_usage_example_util
 	usage_example_util.cpp
+    test_data_helpers.cpp
+    test_data_helpers.h
 )
 
 target_link_libraries(
     Test_usage_example_util
     PUBLIC
         ${RAWTOACES_UTIL_LIB}
         OpenImageIO::OpenImageIO
+    PRIVATE
+        nlohmann_json::nlohmann_json
 )
 
 setup_test_coverage(Test_usage_example_util)
@@ -56,6 +62,8 @@ add_executable (
 	Test_SpectralData
 	test_SpectralData.cpp
 	test_utils.cpp
+    test_data_helpers.cpp
+    test_data_helpers.h
 )
 
 target_link_libraries(
@@ -76,7 +84,9 @@ add_executable (
 	Test_IDT
 	testIDT.cpp
 	test_utils.cpp
-    	../src/misc/pragma.h
+    test_data_helpers.cpp
+    test_data_helpers.h
+    ../src/misc/pragma.h
 )
 
 target_link_libraries(
@@ -114,7 +124,9 @@ add_executable (
 	Test_DNGIdt
 	testDNGIdt.cpp
 	test_utils.cpp
-    	../src/misc/pragma.h
+    test_data_helpers.cpp
+    test_data_helpers.h
+    ../src/misc/pragma.h
 )
 
 target_link_libraries(
@@ -186,6 +198,8 @@ add_executable (
 	Test_UsageTimer
 	testUsageTimer.cpp
 	test_utils.cpp
+    test_data_helpers.cpp
+    test_data_helpers.h
 )
 
 target_link_libraries(
@@ -206,6 +220,8 @@ add_executable (
     Test_Cache
     testCache.cpp
     test_utils.cpp
+    test_data_helpers.cpp
+    test_data_helpers.h
 )
 
 target_link_libraries(
@@ -226,6 +242,8 @@ add_executable (
     Test_Exiftool
     testExiftool.cpp
     test_utils.cpp
+    test_data_helpers.cpp
+    test_data_helpers.h
 )
 
 target_link_libraries(
@@ -248,6 +266,8 @@ if ( RTA_ENABLE_LENSFUN )
         Test_LensCorrection
         testLensCorrection.cpp
         test_utils.cpp
+        test_data_helpers.cpp
+        test_data_helpers.h
     )
 
     target_link_libraries(
@@ -270,6 +290,8 @@ add_executable (
     Test_ColourTransforms
     testColourTransforms.cpp
     test_utils.cpp
+    test_data_helpers.cpp
+    test_data_helpers.h
 )
 
 target_link_libraries(
@@ -291,6 +313,8 @@ add_executable (
 	test_image_converter.cpp
 	test_utils.cpp
 	test_utils_image_converter.cpp
+	test_data_helpers.cpp
+	test_data_helpers.h
 )
 
 target_link_libraries(

tests/test_data_helpers.cpp

@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Contributors to the rawtoaces Project.
+
+#include "test_data_helpers.h"
+
+#include <nlohmann/json.hpp>
+#include <fstream>
+
+// Parametric spectral curve in the form of Gaussian function with asymmetric
+// shape: f(x) = a * exp( - (x - b)^2 / 2c^2 ) )
+// Where:
+//    a - maximum value
+//    b - wavelength at peak
+//    c - shape, c = c1 to the left of the peak, c2 otherwise.
+//    HWHM is roughly 1.177 * c
+struct SpectralCurve
+{
+    const char *name;
+    float       a;
+    float       b;
+    float       c1;
+    float       c2;
+};
+
+struct SpectralCurve HypotheticalCamera[] = {
+    { "R", 0.7f, 600.0f, 50.0f, 40.0f },
+    { "G", 1.0f, 520.0f, 40.0f, 50.0f },
+    { "B", 0.9f, 450.0f, 20.0f, 60.0f }
+};
+
+struct SpectralCurve HypotheticalIlluminant[] = {
+    { "power", 102.17f, 479.5f, 69.2f, 333.8f }
+};
+
+struct SpectralCurve HypotheticalObserver[] = {
+    { "X", 1.06f, 599.0f, 36.0f, 31.4f },
+    { "Y", 1.02f, 553.0f, 36.4f, 47.1f },
+    { "Z", 1.86f, 444.1f, 16.9f, 28.6f }
+};
+
+struct SpectralCurve HypotheticalTrainingData[] = {
+    { "dark skin", 0.23f, 853.2f, 243.3f, 868.5f },
+    { "light skin", 0.84f, 876.7f, 254.5f, 935.0f },
+    { "blue sky", 0.34f, 152.7f, 686.5f, 409.3f },
+    { "foliage", 0.12f, 564.2f, 108.6f, 2765.7f },
+    { "blue flower", 0.86f, -179871.6f, 281557.4f, 127679.8f },
+    { "bluish green", 0.48f, 472.6f, 58.8f, 176.6f },
+    { "orange", 0.64f, 636.9f, 63.0f, 25075.8f },
+    { "purplish blue", 0.21f, -78.6f, 1605.9f, 6790.9f },
+    { "moderate red", 0.61f, 646.9f, 48.2f, 8427.9f },
+    { "purple", 2.67f, -2277037.9f, 3551360.2f, 991385.8f },
+    { "yellow green", 0.44f, 531.5f, 37.1f, 323.0f },
+    { "orange yellow", 0.67f, 617.9f, 67.3f, 28865.4f },
+    { "blue", 0.30f, 450.5f, 35.5f, 42.1f },
+    { "green", 0.25f, 512.2f, 36.0f, 137.9f },
+    { "red", 0.72f, 655.4f, 35.3f, 17634.9f },
+    { "yellow", 0.77f, 580.8f, 55.0f, 27054.0f },
+    { "magenta", 0.54f, -597175.3f, 1237915.0f, 989153.3f },
+    { "cyan", 0.42f, 474.6f, 57.0f, 67.8f },
+    { "white 9.5 (.05 D)", 0.92f, 434.8f, 28.9f, 67276.6f },
+    { "neutral 8 (.23 D)", 0.59f, 427.0f, 28.0f, 1079.5f },
+    { "neutral 6.5 (.44 D)", 0.36f, 424.8f, 31.9f, 760.2f },
+    { "neutral 5 (.70 D)", 0.19f, 426.6f, 42.1f, 645.7f },
+    { "neutral 3.5 (1.05 D)", 0.09f, 532.9f, 337.3f, 431.0f },
+    { "black 2 (1.5 D)", 0.03f, 1025.5f, 8281.3f, 10129.4f }
+};
+
+template <size_t size>
+rta::core::SpectralData generate_spectral_data(
+    const struct SpectralCurve ( &curves )[size],
+    const std::string &manufacturer = "",
+    const std::string &model        = "",
+    const std::string &type         = "" )
+{
+    rta::core::SpectralData result;
+    result.manufacturer     = manufacturer;
+    result.model            = model;
+    result.type             = type;
+    result.license          = "Apache-2.0";
+    result.document_creator = "rawtoaces";
+    result.creation_date    = "2026-01-01T00:00:00Z";
+    result.description = "Hypothetical spectral curves for testing purposes";
+
+    result.data.emplace( "main", rta::core::SpectralData::SpectralSet() );
+
+    rta::core::Spectrum::Shape shape = rta::core::Spectrum::ReferenceShape;
+
+    for ( size_t i = 0; i < size; i++ )
+    {
+        auto  channel_name = curves[i].name;
+        auto &channel      = result.data["main"].emplace_back(
+            rta::core::SpectralData::SpectralChannel(
+                channel_name, rta::core::Spectrum( 0, shape ) ) );
+
+        float a  = curves[i].a;
+        float b  = curves[i].b;
+        float c1 = curves[i].c1;
+        float c2 = curves[i].c2;
+
+        size_t index = 0;
+        for ( float wl = shape.first; wl <= shape.last; wl += shape.step )
+        {
+            float c     = wl < b ? c1 : c2;
+            float value = a * expf( -powf( wl - b, 2.0f ) / 2.0f / c / c );
+            channel.second.values[index] = value;
+            index++;
+        }
+    }
+
+    return result;
+}
+
+rta::core::SpectralData
+create_hypothetical_camera( const std::string &make, const std::string &model )
+{
+    return generate_spectral_data( HypotheticalCamera, make, model, "" );
+}
+
+rta::core::SpectralData
+create_hypothetical_illuminant( const std::string &type )
+{
+    return generate_spectral_data( HypotheticalIlluminant, "", "", type );
+}
+
+rta::core::SpectralData create_hypothetical_observer()
+{
+    return generate_spectral_data( HypotheticalObserver );
+}
+
+rta::core::SpectralData create_hypothetical_training_data()
+{
+    return generate_spectral_data( HypotheticalTrainingData );
+}
+
+void save_spectral_json(
+    const rta::core::SpectralData &data, const std::string &filename )
+{
+    nlohmann::json json_header;
+
+    json_header["schema_version"]         = "1.0.0";
+    json_header["description"]            = data.description;
+    json_header["document_creator"]       = data.document_creator;
+    json_header["document_creation_date"] = data.creation_date;
+    json_header["license"]                = data.license;
+
+    if ( !data.manufacturer.empty() )
+        json_header["manufacturer"] = data.manufacturer;
+
+    if ( !data.model.empty() )
+        json_header["model"] = data.model;
+
+    if ( !data.type.empty() )
+        json_header["type"] = data.type;
+
+    nlohmann::json json_data;
+    json_data["header"] = json_header;
+
+    for ( const auto &set_item: data.data )
+    {
+        const auto &set_name = set_item.first;
+        const auto &set_data = set_item.second;
+
+        std::vector<std::string> channels;
+        for ( const auto &item: set_data )
+        {
+            channels.push_back( item.first );
+        }
+
+        assert( !set_data.empty() );
+
+        nlohmann::json json_spectral_data;
+
+        const auto &shape = set_data[0].second.shape;
+
+        size_t index = 0;
+        for ( float wl = shape.first; wl <= shape.last; wl += shape.step )
+        {
+            std::vector<double> values( channels.size() );
+
+            for ( size_t channel = 0; channel < channels.size(); channel++ )
+            {
+                values[channel] = set_data[channel].second.values[index];
+            }
+
+            json_spectral_data[std::to_string( int( wl ) )] = values;
+            index++;
+        }
+        json_data["spectral_data"]["data"][set_name]  = json_spectral_data;
+        json_data["spectral_data"]["index"][set_name] = channels;
+        json_data["spectral_data"]["units"]           = "relative";
+    }
+
+    std::ofstream file( filename );
+    file << json_data.dump( 4 );
+}

tests/test_data_helpers.h

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Contributors to the rawtoaces Project.
+
+#pragma once
+
+#include <rawtoaces/spectral_data.h>
+
+// The make and model parameters only affect the metadata, not the curves shape.
+rta::core::SpectralData create_hypothetical_camera(
+    const std::string &make  = "TEST_CAMERA_MAKE",
+    const std::string &model = "TEST_CAMERA_MODEL" );
+
+// The type parameter only affects the metadata, not the curve shape.
+rta::core::SpectralData
+create_hypothetical_illuminant( const std::string &type = "TEST_ILLUMINANT" );
+
+rta::core::SpectralData create_hypothetical_observer();
+
+rta::core::SpectralData create_hypothetical_training_data();
+
+void save_spectral_json(
+    const rta::core::SpectralData &data, const std::string &filename );

tests/test_image_converter.cpp

@@ -1440,7 +1440,7 @@ void test_auto_detect_illuminant_with_wb_multipliers()
         "",
         { "Warning: Directory '",
           "illuminant' does not exist.",
-          "Found illuminant: '2000k'." } );
+          "Found illuminant: 'd60'." } );
 }
 
 /// Tests that a warning is issued when a database location path points to a file instead of a directory
@@ -2038,7 +2038,7 @@ void test_auto_detect_illuminant_from_raw_metadata()
         WB_multipliers,
         true,
         "",
-        { "Found illuminant: '2000k'." } );
+        { "Found illuminant: 'd60'." } );
 }
 
 /// Tests that auto-detection normalizes white balance multipliers when min_val > 0 and != 1
@@ -2077,7 +2077,7 @@ void test_auto_detect_illuminant_with_normalization()
         WB_multipliers,
         true,
         "",
-        { "Found illuminant: '1500k'." } );
+        { "Found illuminant: 'd55'." } );
 }
 
 /// Tests that prepare_transform_spectral fails when IDT matrix calculation fails