Adds 16 bits support to histogram calculation

Modifies code to accept any encoding depth.
Updates tests to fit with code modifications.
Adds example in order to present a strange case with different encoding
depth and actual pixel values.
Adds an image that fits with the example

Reported-by: Julien Lengrand-Lambert
Signed-off-by: Julien Lengrand-Lambert <julien@lengrandlambert.fr>

examples/histogram_display.py

@@ -21,18 +21,23 @@ import cv
 import tippy.statistics as st
 import tippy.display_operations as do
 
-<<<<<<< HEAD
+# test with 8 bits color image
 img_name = "tippy/data/tippy.jpg"
 img = cv.LoadImage(img_name, cv.CV_LOAD_IMAGE_COLOR)
 hist = st.Histogram(img)
-
+    
 imgs = hist.to_images() # list of Red, Green, Blue channels
 do.display_single_image(imgs[2], "Blue channel histogram of the tippy image")
-=======
-img_name = "tippy/data/gnu.jpg"
-img = cv.LoadImage(img_name, cv.CV_LOAD_IMAGE_COLOR)
-hist = st.Histogram(img)
 
-hist_img = hist.hist2image() 
 
-do.display_single_image(hist_img[0], "Gray-Level histogram of the gnu image")
+# test 16 bits histogram, with 4096 range
+# special tortuous case :
+# 12 bits encoded image
+# Taken as 16 bits image, only histogram range to be changed. 
+img_name = "tippy/data/peaks.tif"
+img = cv.LoadImage(img_name, cv.CV_LOAD_IMAGE_UNCHANGED)
+img_depth = 12
+hist = st.Histogram(img, img_depth)
+    
+tables = hist.to_tables() # list of values. Only one item in list
+print max(tables[0]) # search for the max value of histogram  

tippy/statistics.py

@@ -46,9 +46,9 @@ class Histogram():
                             % (sys._getframe().f_code.co_name))
         
         # img test
-        if not(img.depth == cv.IPL_DEPTH_8U):
-            raise TypeError("(%s) 8U image expected!" 
-                            % (sys._getframe().f_code.co_name))
+        #if not(img.depth == cv.IPL_DEPTH_8U):
+        #    raise TypeError("(%s) 8U image expected!" 
+        #                    % (sys._getframe().f_code.co_name))
         if img.nChannels not in [1, 3]:
             raise ValueError("(%s) 1 or 3 channels image expected!" 
                             % (sys._getframe().f_code.co_name))        
@@ -68,7 +68,7 @@ class Histogram():
         self.channels = img.nChannels
         self.nb_bins = int(pow(2, bin_fact))
         self.depth = int(img.depth)
-        max_range = pow(2, self.depth)
+        max_range = pow(2, bin_fact) + min_range - 1
         self.ranges = [min_range, max_range]
         
         img_list = []
@@ -88,13 +88,8 @@ class Histogram():
         
     def _compute_1ch_histogram(self, img_list):
         """
-<<<<<<< HEAD
-        DESIGNED FOR INTERNAL USE ONLY.
-        BE CAREFUL, NO VERIFICATIONS PERFORMED
-=======
         DESIGNED FOR INTERNAL USE ONLY
         CAREFUL, NO VERIFICATIONS PERFORMED
->>>>>>> 335108ecf6cb601da09717b94407e54e677b9cee
         """
         dims = [self.nb_bins]
         all_ranges = [self.ranges]
@@ -102,11 +97,10 @@ class Histogram():
         hist_list = [] 
         for img in img_list:
             hist = cv.CreateHist( dims, 
-                              cv.CV_HIST_ARRAY, 
-                              all_ranges, 
-                              uniform=1)
+                                  cv.CV_HIST_ARRAY, 
+                                  all_ranges, 
+                                  uniform=1)
             cv.CalcHist([img], hist)
-            
             hist_list.append(hist)   
 
         return hist_list

tippy/tests/test_statistics.py

@@ -36,7 +36,7 @@ class Test(unittest.TestCase):
     def test_compute_histogram(self):
         # testing input image
         self.assertRaises(TypeError, lambda:st.Histogram(self.val) )
-        self.assertRaises(TypeError, lambda:st.Histogram(self.img_16s) )        
+        #self.assertRaises(TypeError, lambda:st.Histogram(self.img_16s) )        
         self.assertRaises(ValueError, lambda:st.Histogram(self.img_2c) )      
         # testing bin_fact
         self.assertRaises(ValueError, 
@@ -47,7 +47,6 @@ class Test(unittest.TestCase):
         # testing min_range. It can be either negative or even.
         self.assertRaises(TypeError, 
                           lambda: st.Histogram(self.img_1c, self.val, self.string))     
-<<<<<<< HEAD
 
         # testing output
         hist_1c = st.Histogram(self.img_1c)
@@ -71,7 +70,6 @@ class Test(unittest.TestCase):
                           lambda: hist.channel_to_image(self.string))
         self.assertRaises(TypeError, 
                           lambda: hist.channel_to_image(self.neg_val))        
-=======
 
         # testing output
         hist_1c = st.Histogram(self.img_1c)
@@ -79,31 +77,6 @@ class Test(unittest.TestCase):
         hist_3c = st.Histogram(self.img_3c)
         self.assertEquals(self.img_3c.nChannels, hist_3c.channels)
 
-    def test_hist2table(self):
-        # testing output size 
-        hist = st.Histogram(self.img_3c)
-        histable = hist.hist2table()
-        self.assertEqual(3, len(histable))
-        self.assertEqual(256, len(histable[0]))
-        
-    def test_hist2image(self):     
-        hist = st.Histogram(self.img_1c)
->>>>>>> 335108ecf6cb601da09717b94407e54e677b9cee
-        # testing scale inputs 
-        self.assertRaises(TypeError, 
-                          lambda: hist.channel_to_image(1, self.string))
-        self.assertRaises(TypeError, 
-                          lambda: hist.channel_to_image(1, self.neg_val))
-        self.assertRaises(TypeError, 
-                          lambda: hist.channel_to_image(1, self.val, self.string))
-        self.assertRaises(TypeError, 
-                          lambda: hist.channel_to_image(1, self.val, self.neg_val))
-        # testing range inputs
-        self.assertRaises(TypeError, 
-                          lambda: hist.channel_to_image(1, self.val, self.val, self.string))
-        self.assertRaises(TypeError, 
-                          lambda: hist.channel_to_image(1, self.val, self.val, self.neg_val))
-
     def test_to_images(self):
         hist = st.Histogram(self.img_3c)
         # testing scale inputs