improved jellyfin support

src/embed_faces.cpp

@@ -129,6 +129,13 @@ static FaceResult process(const std::string& path,
 
     std::vector<DetectedFace> faces = detect(img);
 
+    if (faces.empty()) {
+        cv::Mat enhanced = enhance_for_retry(img);
+        faces = detect(enhanced);
+        if (!faces.empty())
+            img = enhanced;
+    }
+
     if (faces.empty()) {
         res.error = "no face detected";
         return res;

src/face_embedder_engine.hpp

@@ -66,6 +66,12 @@ public:
         }
 
         std::vector<DetectedFace> faces = detector_->detect(img);
+        if (faces.empty()) {
+            cv::Mat enhanced = enhance_for_retry(img);
+            faces = detector_->detect(enhanced);
+            if (!faces.empty())
+                img = enhanced;
+        }
         if (faces.empty()) {
             res.error = "no face detected";
             return res;

src/face_utils.hpp

@@ -24,6 +24,28 @@ inline cv::Mat align_face(const cv::Mat& img,
     return crop;
 }
 
+// ── enhance_for_retry ────────────────────────────────────────────────────────
+// Used when initial face detection finds nothing. Pads the image by 50%
+// (border-replicated, so the detector doesn't see a hard edge) and applies
+// CLAHE to boost local contrast, giving the detector a second try.
+inline cv::Mat enhance_for_retry(const cv::Mat& img) {
+    cv::Mat padded;
+    const int pad_x = img.cols / 4;
+    const int pad_y = img.rows / 4;
+    cv::copyMakeBorder(img, padded, pad_y, pad_y, pad_x, pad_x, cv::BORDER_REPLICATE);
+
+    cv::Mat lab;
+    cv::cvtColor(padded, lab, cv::COLOR_BGR2Lab);
+    std::vector<cv::Mat> channels;
+    cv::split(lab, channels);
+    cv::createCLAHE(2.0, cv::Size(8, 8))->apply(channels[0], channels[0]);
+    cv::merge(channels, lab);
+
+    cv::Mat out;
+    cv::cvtColor(lab, out, cv::COLOR_Lab2BGR);
+    return out;
+}
+
 // ── l2_normalise ──────────────────────────────────────────────────────────────
 inline Embedding l2_normalise(const float* row) {
     float norm = 0.f;