Merge pull request #29281 from pranavkaushik1:improve-qrcode-colors

samples: add color-coded bounding boxes for multi QR code detection #29281

Improves the existing qrcode.py sample by adding color-coded bounding boxes when multiple QR codes are detected simultaneously.

Previously all QR codes were drawn with the same green color, making it hard to distinguish between them visually.

This change adds a QR_COLORS palette so each detected QR code gets a unique color, improving visual clarity for multi-QR detection.

Co-authored-by: Ayush Gupta <gupta.ayushg@gmail.com>

samples/python/qrcode.py

@@ -21,6 +21,18 @@ PY3 = sys.version_info[0] == 3
 if PY3:
     xrange = range
 
+# Colors for distinguishing multiple QR codes visually
+QR_COLORS = [
+    (0, 255, 0),    # green
+    (255, 0, 0),    # blue
+    (0, 0, 255),    # red
+    (255, 255, 0),  # cyan
+    (0, 255, 255),  # yellow
+    (255, 0, 255),  # magenta
+    (128, 255, 0),  # lime
+    (255, 128, 0),  # orange
+]
+
 
 class QrSample:
     def __init__(self, args):
@@ -46,15 +58,14 @@ class QrSample:
         cv.putText(result, message, (20, 20), 1,
                    cv.FONT_HERSHEY_DUPLEX, (0, 0, 255))
 
-    def drawQRCodeContours(self, image, cnt):
+    def drawQRCodeContours(self, image, cnt, color=(0, 255, 0)):
         if cnt.size != 0:
             rows, cols, _ = image.shape
             show_radius = 2.813 * ((rows / cols) if rows > cols else (cols / rows))
             contour_radius = show_radius * 0.4
-            cv.drawContours(image, [cnt], 0, (0, 255, 0), int(round(contour_radius)))
+            cv.drawContours(image, [cnt], 0, color, int(round(contour_radius)))
             tpl = cnt.reshape((-1, 2))
             for x in tuple(tpl.tolist()):
-                color = (255, 0, 0)
                 cv.circle(image, tuple(x), int(round(contour_radius)), color, -1)
 
     def drawQRCodeResults(self, result, points, decode_info, fps):
@@ -64,7 +75,8 @@ class QrSample:
         if n > 0:
             for i in range(n):
                 cnt = np.array(points[i]).reshape((-1, 1, 2)).astype(np.int32)
-                self.drawQRCodeContours(result, cnt)
+                color = QR_COLORS[i % len(QR_COLORS)]
+                self.drawQRCodeContours(result, cnt, color)
                 msg = 'QR[{:d}]@{} : '.format(i, *(cnt.reshape(1, -1).tolist()))
                 print(msg, end="")
                 if len(decode_info) > i: