changed equalization method

Author: oseiskar

imgutils.py

@@ -3,13 +3,28 @@
 
 import numpy as np
 
-class EncodingSettings:
+class ColorEncodingSettings:
     def __init__(self):
+        
+        ## Color endcoding pipeline
+        
+        # First the intensity values are shifted downwards so that this
+        # reference point has zero brightness = (r+g+b)/3
+        self.low_normalization = np.min
+        
+        # Then the values are scaled linearly so that this reference
+        # point becomes equal to the below brightness value
+        self.brightness_reference = np.mean
+        self.brightness = 0.4
+        
+        # Then gamma correction x -> x^(1/gamma) is applied
         self.gamma = 1.8
-        self.brightness = 0.3
-        self.normalization = 'mean'
-        self.equalize = True
+        
+        # If set, over-exposed values are blurred with a flare effect
         self.flares = False
+        
+        # Finally, all color values are clamped to range [0,1] and
+        # encoded using 8-bit
 
 class Image:
 
@@ -19,7 +34,7 @@ def __init__( self, npy_filename = None, data = None, settings = None ):
         else:
             self.data = np.load( npy_filename )
 
-        if settings is None: settings = EncodingSettings()
+        if settings is None: settings = ColorEncodingSettings()
         self.settings = settings
 
         self._pgwin = None
@@ -41,21 +56,23 @@ def _sum( self, imgdata ):
 
     def _to_24bit( self, imgdata = None ):
         imgdata = np.nan_to_num(self._sum( imgdata ))
-        ref = getattr(np, self.settings.normalization)(imgdata)
+        lightness = np.ravel(np.mean(imgdata, 2))
+        
+        lo_norm = self.settings.low_normalization
+        if lo_norm is not None and lo_norm is not 0:
+            min_l = lo_norm(lightness)
+            imgdata -= min_l
+            lightness -= min_l
+        
+        ref = self.settings.brightness_reference(lightness)
 
         imgdata = np.clip(imgdata/ref*self.settings.brightness, 0, None)
         imgdata = np.power(imgdata, 1.0/self.settings.gamma)
+        
         if self.settings.flares:
             imgdata = flares(imgdata)
+        
         imgdata = np.clip(imgdata, 0, 1.0)
-        if self.settings.equalize:
-            lightness = np.mean(imgdata, 2)
-            min_l = np.min(lightness)
-            max_l = np.max(lightness)
-            
-            if min_l != max_l:
-                imgdata = (imgdata - min_l) / (max_l - min_l)
-                imgdata = np.clip(imgdata, 0, 1.0)
 
         return (imgdata*255).astype(np.uint8)
 

scene.py

@@ -1,6 +1,6 @@
 import numpy as np
 import camera
-from imgutils import EncodingSettings
+from imgutils import ColorEncodingSettings
 
 class Scene:
     """
@@ -21,7 +21,7 @@ def __init__(self, tracer, material, name=None):
             self.name = name
             self.bidirectional_light = False
 
-    class ImageSettings(EncodingSettings):
+    class ImageSettings(ColorEncodingSettings):
         pass
 
     def get_camera_rotmat(self):

scenes/default_scenes.py

@@ -82,10 +82,6 @@ def default_settings(scene):
     # --- Image settings
     scene.image = Scene.ImageSettings()
     scene.image.size = (800, 600)
-    scene.image.brightness = 0.3
-    scene.image.gamma = 1.8
-    scene.image.brightness_reference = 'mean'
-    scene.image.equalize = True
 
     # --- Raytracer settings
     scene.tent_filter = True

scenes/scene-test.py

@@ -103,4 +103,7 @@ def load_triangle_mesh_in_octree(p, R, **kwargs):
 scene.max_bounces = 4
 scene.min_bounces = 2
 
+scene.image.brighness_reference = numpy.max
+scene.brightness = 1.0
+
 scene.direct_camera_towards((0,0,0.0))