Koncno dela

assignment2/solution.py

@@ -10,8 +10,9 @@ import uz_framework.image as uz_image
 #################################################################
 def ex1():
     one_a()
+    #one_b()
 
-def one_a():
+def one_a() -> npt.NDArray[np.float64]:
     """
      Firstly, you will implement the function myhist3 that computes a 3-D histogram
     from a three channel image. The images you will use are RGB, but the function
@@ -24,10 +25,22 @@ def one_a():
     the resulting histogram.
     """
     test_image = uz_image.imread('./data/images/museum.jpg', uz_image.ImageType.float64)
-    uz_image.get_image_bins_ND(test_image, 10)
-    plt.imshow(test_image)
-    plt.show()
+    bins = uz_image.get_image_bins_ND(test_image, 10)
+    return bins
 
+def one_b():
+    """
+     In order to perform image comparison using histograms, we need to implement
+     some distance measures. These are defined for two input histograms and return a
+     single scalar value that represents the similarity (or distance) between the two histograms.
+     Implement a function compare_histograms that accepts two histograms
+     and a string that identifies the distance measure you wish to calculate
+     Implement L2 metric, chi-square distance, intersection and Hellinger distance.
+    """ 
+    test_image = uz_image.imread('./data/images/museum.jpg', uz_image.ImageType.float64)
+    bins = uz_image.get_image_bins_ND(test_image, 10)
+
+    uz_image.compare_two_histograms(bins[0], bins[1], uz_image.DistanceMeasure.chi_square_distance)
 
 # ######## #
 # SOLUTION #

assignment2/uz_framework/image.py

@@ -11,6 +11,12 @@ class ImageType(enum.Enum):
     uint8 = 0
     float64 = 1
 
+class DistanceMeasure(enum.Enum):
+    euclidian_distance = 0
+    chi_square_distance = 1
+    intersection_distance = 2
+    hellinger_distance = 3
+
 def imread(path: str, type: ImageType) -> Union[npt.NDArray[np.float64],  npt.NDArray[np.uint8]]:
     """
     Reads an image in RGB order. Image type is transformed from uint8 to float, and
@@ -210,12 +216,43 @@ def get_image_bins(image: Union[npt.NDArray[np.float64],  npt.NDArray[np.uint8]]
         for i in empty_bins:
             counts = np.insert(counts, i - 1, 0)
 
-    return counts / np.sum(counts)
+    return counts
 
 def get_image_bins_ND(image: Union[npt.NDArray[np.float64],  npt.NDArray[np.uint8]], number_of_bins: int) -> npt.NDArray[np.float64]:
-    for dimension in range(image.shape[2]):
-        print(get_image_bins(image[dimension], number_of_bins))
-    return None
+    
+    bs = [] 
+    hist = np.zeros((number_of_bins, number_of_bins, number_of_bins))
+    if image.dtype.type == np.uint8:
+        bins = np.linspace(0, 255, num=number_of_bins) 
+    elif image.dtype.type == np.float64:
+        bins = np.linspace(0, 1, num=number_of_bins) 
+    else:
+        raise Exception('Unsuported datatype!')
+
+    for i in range(image.shape[2]):
+        v = image[:, :, i].reshape(-1)
+        bs.append(np.digitize(v, bins).astype(np.uint32))
+
+    for i in range(len(bs[0])):
+        hist[bs[2][i] -1, bs[1][i] -1, bs[0][i] - 1] += 1
+
+    return hist / np.sum(hist)
+
+def compare_two_histograms(h1: npt.NDArray[np.float64], h2: npt.NDArray[np.float64], method: DistanceMeasure) -> float:
+
+    if method == DistanceMeasure.euclidian_distance:
+        d = np.sqrt(np.sum(np.square(h1 - h2)))
+    elif method == DistanceMeasure.chi_square_distance:
+        d = 0.5 * np.sum(np.square(h1 - h2) / (h1 + h2 + np.finfo(float).eps))
+    elif method == DistanceMeasure.intersection_distance:
+        d = 0.0
+    elif method == DistanceMeasure.hellinger_distance:
+        d = 0.0
+    else:
+        raise Exception('Unsuported method chosen!')
+
+
+    return d 
     
 
 def apply_mask_on_image(image: Union[npt.NDArray[np.float64],  npt.NDArray[np.uint8]], mask: npt.NDArray[np.uint8]):