include Contrast class in BivariateSequence class

itten/views.py

@@ -286,9 +286,13 @@ class BivariateSequence(View):
                 else:
                     maxs.append(int(total_value / sum(hist_maxs)) + 127)
 
+            # peak strategy
             else:
-                hist_value = cv2.calcHist([img_hsv], [self._channel],
-                                          None, [256], [0, 256])
+                ctrst_cls = self._get_ctrst_cls_name(self._contrast)
+                ctrst_img = ctrst_cls(img).ctrst
+
+                hist_value, _ = np.histogram(ctrst_img.flatten(),
+                                             bins=self._bins, range=(0, 256))
 
                 peaks = peakutils.indexes(hist_value.flatten(), thres=0.2,
                                           min_dist=15)