add shirnk parmater to demo_agg_filter.LightFilter

leejjoon · leejjoon · commit 74c016d15cc6 · 2022-10-24T22:56:31.000+09:00
diff --git a/examples/misc/demo_agg_filter.py b/examples/misc/demo_agg_filter.py
@@ -99,16 +99,40 @@ def process_image(self, padded_src, dpi):
 
 
 class LightFilter(BaseFilter):
-
-    def __init__(self, sigma, fraction=1):
+    """Apply LightSource filter"""
+
+    def __init__(self, sigma, fraction=1, shrink=None):
+        """
+        Parameters
+        ----------
+        sigma : float
+            sigma for gaussian filter
+        shrink: int or None: default None
+            kernel size of the grey_erosion filter. This will
+            effectively shrink the size of the base image, which
+            can compansate the increased image footprint due to
+            the gaussian filter.
+        fraction: number: deault 1
+            Increases or decreases the contrast of the hillshade.
+            See `matplotlib.colors.LightSource`
+
+        """
         self.gauss_filter = GaussianFilter(sigma, alpha=1)
         self.light_source = LightSource()
         self.fraction = fraction
+        self.shrink = shrink
 
     def get_pad(self, dpi):
         return self.gauss_filter.get_pad(dpi)
 
     def process_image(self, padded_src, dpi):
+        if self.shrink is not None:
+            import scipy.ndimage as NI
+            # we shrink the image a bit.
+            padded_src = np.stack([NI.grey_erosion(padded_src[:, :, i],
+                                                   [self.shrink, self.shrink])
+                                   for i in range(padded_src.shape[-1])],
+                                  axis=-1)
         t1 = self.gauss_filter.process_image(padded_src, dpi)
         elevation = t1[:, :, 3]
         rgb = padded_src[:, :, :3]
@@ -261,7 +285,7 @@ def light_filter_pie(ax):
     explode = (0, 0.05, 0, 0)
     pies = ax.pie(fracs, explode=explode)
 
-    light_filter = LightFilter(9)
+    light_filter = LightFilter(9, shrink=5)
     for p in pies[0]:
         p.set_agg_filter(light_filter)
         p.set_rasterized(True)  # to support mixed-mode renderers
