Add GPU validation and configuration support in NumberRecognitionEngine

src/AIFotoONLUS.Core/AIFotoONLUS.Core.xml

@@ -139,6 +139,12 @@
             must match the class ordering used by the trained recognition network.
             </summary>
         </member>
+        <member name="P:AIFotoONLUS.Core.ModelConfiguration.UseGpu">
+            <summary>
+            When enabled, request OpenCV DNN CUDA backend/target for inference.
+            The installed OpenCV runtime must have CUDA support or model loading/forwarding may fail.
+            </summary>
+        </member>
         <member name="P:AIFotoONLUS.Core.ModelConfiguration.EnableCropSaving">
             <summary>
             When enabled, recognition crops will be saved to disk under

src/AIFotoONLUS.Core/ModelConfiguration.cs

@@ -55,6 +55,12 @@ namespace AIFotoONLUS.Core
         /// </summary>
         public string[] NumberClasses { get; set; } = new[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
 
+        /// <summary>
+        /// When enabled, request OpenCV DNN CUDA backend/target for inference.
+        /// The installed OpenCV runtime must have CUDA support or model loading/forwarding may fail.
+        /// </summary>
+        public bool UseGpu { get; set; } = false;
+
         /// <summary>
         /// When enabled, recognition crops will be saved to disk under
         /// "logs/crops" for diagnostic inspection. Disabled by default.

src/AIFotoONLUS.Core/NumberRecognitionEngine.cs

@@ -95,10 +95,8 @@ namespace AIFotoONLUS.Core
             _detectionNet = CvDnn.ReadNetFromDarknet(_cfg.DetectionCfg, _cfg.DetectionWeights);
             _recognitionNet = CvDnn.ReadNetFromDarknet(_cfg.RecognitionCfg, _cfg.RecognitionWeights);
 
-            _detectionNet.SetPreferableBackend(Backend.OPENCV);
+            ConfigureNetRuntime(_detectionNet, _cfg.UseGpu);
-            _detectionNet.SetPreferableTarget(Target.CPU);
+            ConfigureNetRuntime(_recognitionNet, _cfg.UseGpu);
-            _recognitionNet.SetPreferableBackend(Backend.OPENCV);
-            _recognitionNet.SetPreferableTarget(Target.CPU);
             // Let OpenCV use multiple threads internally (use number of logical processors)
             try
             {
@@ -108,6 +106,11 @@ namespace AIFotoONLUS.Core
             {
                 // Ignore if not supported by OpenCvSharp build
             }
+
+            if (_cfg.UseGpu)
+            {
+                ValidateGpuRuntime();
+            }
         }
 
         public void Dispose()
@@ -119,6 +122,38 @@ namespace AIFotoONLUS.Core
             GC.SuppressFinalize(this);
         }
 
+        public static bool TryValidateGpuRuntime(ModelConfiguration cfg, ILogger? logger, out string? failureMessage)
+        {
+            if (cfg is null) throw new ArgumentNullException(nameof(cfg));
+
+            var probeConfiguration = new ModelConfiguration
+            {
+                DetectionCfg = cfg.DetectionCfg,
+                DetectionWeights = cfg.DetectionWeights,
+                RecognitionCfg = cfg.RecognitionCfg,
+                RecognitionWeights = cfg.RecognitionWeights,
+                ConfidenceThreshold = cfg.ConfidenceThreshold,
+                NmsThreshold = cfg.NmsThreshold,
+                DetectionInputSize = cfg.DetectionInputSize,
+                RecognitionInputSize = cfg.RecognitionInputSize,
+                NumberClasses = cfg.NumberClasses,
+                EnableCropSaving = cfg.EnableCropSaving,
+                UseGpu = true
+            };
+
+            try
+            {
+                using var engine = new NumberRecognitionEngine(probeConfiguration, logger);
+                failureMessage = null;
+                return true;
+            }
+            catch (Exception ex)
+            {
+                failureMessage = ex.GetBaseException().Message;
+                return false;
+            }
+        }
+
         private static string SanitizeFileName(string name)
         {
             foreach (var c in Path.GetInvalidFileNameChars()) name = name.Replace(c, '_');
@@ -127,6 +162,39 @@ namespace AIFotoONLUS.Core
 
         private string[] GetOutputLayerNames(Net net) => net.GetUnconnectedOutLayersNames();
 
+        private static void ConfigureNetRuntime(Net net, bool useGpu)
+        {
+            if (useGpu)
+            {
+                net.SetPreferableBackend(Backend.CUDA);
+                net.SetPreferableTarget(Target.CUDA);
+                return;
+            }
+
+            net.SetPreferableBackend(Backend.OPENCV);
+            net.SetPreferableTarget(Target.CPU);
+        }
+
+        private void ValidateGpuRuntime()
+        {
+            try
+            {
+                using var detectionProbe = new Mat(_cfg.DetectionInputSize.Height, _cfg.DetectionInputSize.Width, MatType.CV_8UC3, Scalar.All(0));
+                _ = DetectTextRegions(_detectionNet, detectionProbe).Take(1).ToArray();
+
+                using var recognitionProbe = new Mat(_cfg.RecognitionInputSize.Height, _cfg.RecognitionInputSize.Width, MatType.CV_8UC3, Scalar.All(0));
+                using var blob = CvDnn.BlobFromImage(recognitionProbe, 0.00392, _cfg.RecognitionInputSize, new Scalar(0, 0, 0), true, false);
+                _recognitionNet.SetInput(blob);
+                using var output = _recognitionNet.Forward();
+            }
+            catch (Exception ex)
+            {
+                throw new InvalidOperationException(
+                    "OpenCV DNN CUDA runtime validation failed. Disable number AI GPU mode or use an OpenCV runtime built with CUDA DNN support.",
+                    ex);
+            }
+        }
+
         /// <summary>
         /// Detect text regions in the supplied image using the detection network.
         /// </summary>
@@ -486,10 +554,8 @@ namespace AIFotoONLUS.Core
             {
                 var det = CvDnn.ReadNetFromDarknet(_cfg.DetectionCfg, _cfg.DetectionWeights);
                 var rec = CvDnn.ReadNetFromDarknet(_cfg.RecognitionCfg, _cfg.RecognitionWeights);
-                det.SetPreferableBackend(Backend.OPENCV);
+                ConfigureNetRuntime(det, _cfg.UseGpu);
-                det.SetPreferableTarget(Target.CPU);
+                ConfigureNetRuntime(rec, _cfg.UseGpu);
-                rec.SetPreferableBackend(Backend.OPENCV);
-                rec.SetPreferableTarget(Target.CPU);
                 netsBag.Add((det, rec));
                 return (det, rec);
             });
@@ -525,8 +591,7 @@ namespace AIFotoONLUS.Core
                                     try
                                     {
                                         using var tempRec = CvDnn.ReadNetFromDarknet(_cfg.RecognitionCfg, _cfg.RecognitionWeights);
-                                        tempRec.SetPreferableBackend(Backend.OPENCV);
+                                        ConfigureNetRuntime(tempRec, _cfg.UseGpu);
-                                        tempRec.SetPreferableTarget(Target.CPU);
                                         var alt = RecognizeDigits(crop, tempRec, ctx);
                                         if (!string.IsNullOrEmpty(alt)) txt = alt;
                                     }