Update mosaic plots font size (#4596)

utils/plots.py

@@ -162,7 +162,7 @@ def plot_images(images, targets, paths=None, fname='images.jpg', names=None, max
         mosaic = cv2.resize(mosaic, tuple(int(x * ns) for x in (w, h)))
 
     # Annotate
-    fs = int(h * ns * 0.02)  # font size
+    fs = int((h + w) * ns * 0.01)  # font size
     annotator = Annotator(mosaic, line_width=round(fs / 10), font_size=fs)
     for i in range(i + 1):
         x, y = int(w * (i // ns)), int(h * (i % ns))  # block origin