Update app.py

app.py

@@ -83,14 +83,15 @@ def extract_snow_data_from_chart(image):
         # Dark green (current season): deeper, more saturated green
         # Light green (previous season): lighter, less saturated green
         
-        # Dark green mask (current season) - HSV ranges for dark green
-        dark_green_lower = np.array([35, 100, 50])   # Lower HSV values for dark green
-        dark_green_upper = np.array([85, 255, 180])  # Upper HSV values for dark green
+        # Dark green mask (current season) - Tuned for the specific dark green color shown
+        # This green appears to be in the 60-80 hue range with high saturation
+        dark_green_lower = np.array([55, 150, 80])   # More specific range for the dark green shown
+        dark_green_upper = np.array([75, 255, 200])  # Narrower hue range, higher saturation
         dark_green_mask = cv2.inRange(hsv, dark_green_lower, dark_green_upper)
         
-        # Light green mask (previous season) - HSV ranges for light green  
-        light_green_lower = np.array([35, 30, 120])   # Lower HSV values for light green
-        light_green_upper = np.array([85, 150, 255])  # Upper HSV values for light green
+        # Light green mask (previous season) - Lighter, less saturated version
+        light_green_lower = np.array([50, 60, 150])   # Broader hue, lower saturation for light green
+        light_green_upper = np.array([80, 180, 255])  # Higher brightness for lighter green
         light_green_mask = cv2.inRange(hsv, light_green_lower, light_green_upper)
         
         # 3. Extract data points along chart width for both seasons
@@ -240,10 +241,14 @@ def extract_snow_data_from_chart(image):
 - **Chart boundaries**: {chart_bounds}
 - **Dark green pixels found**: {np.sum(dark_green_mask)} pixels
 - **Light green pixels found**: {np.sum(light_green_mask)} pixels
-- **Color detection**: HSV color space analysis
+- **Color detection**: HSV analysis calibrated to NIWA chart colors
+- **Current season detection**: Tuned for specific dark green (HSV: 55-75, 150-255, 80-200)
+- **Previous season detection**: Tuned for light green (HSV: 50-80, 60-180, 150-255)
 
 **⚠️ Important Notes:**
-- Green line detection using HSV color analysis
+- Green line detection tuned to specific NIWA chart colors
+- Dark green HSV range: [55-75, 150-255, 80-200] (current season)
+- Light green HSV range: [50-80, 60-180, 150-255] (previous season)
 - Estimated snow season: May-November  
 - Y-axis scale assumed: 0-350cm
 - Accuracy depends on chart image quality and color consistency