Add docs

assignment1/solution.py

@@ -12,38 +12,78 @@ def excercise_one() -> None:
     one_c(image)
     one_d(60, 180, 180, 340, image)
     
-# Display image
 def one_a() -> npt.NDArray[np.float64]:
-    image = uz.imread('./images/bird.jpg')
-    #uz.imshow(image, 'Birdie')
+    """
+    Read the image from the file umbrellas.jpg and display it
+    """
+    image = uz.imread('./images/umbrellas.jpg')
+    uz.imshow(image, 'Birdie')
     return image
 
-# Convert loaded image into grayscale
 def one_b(image: npt.NDArray[np.float64]) -> None:
+    """
+    Convert the loaded image to grayscale. A very simple way of doing this is summing
+    up the color channels and dividing the result by 3, effectively averaging the values.
+    The issue, however, is that the sum easily reaches beyond the np.uint8 range. We
+    can avoid that by casting the data to a floating point type. You can access a specific
+    image channel using the indexing syntax like red = I[:,:,0].
+    """
     grayscale_image = np.zeros(image.shape[:2])
     
     for i in range(image.shape[0]):
         for j in range(image.shape[1]):
             grayscale_image[i, j] = (image[i, j, 0] + image[i,j, 1] + image[i, j, 2]) / 3
 
-    #uz.imshow(grayscale_image, 'Birdie grayscale')
+    uz.imshow(grayscale_image, 'Umbrellas grayscale')
 
-# Display birdies head in grayscale
 def one_c(image: npt.NDArray[np.float64]) -> None:
+    """
+    Cut and display a specific part of the loaded image. Extract only one of the channels
+    so you get a grayscale image. You can do this by indexing along the first two axes,
+    for instance: cutout=I[130:260, 240:450, 1]. You can display multiple images in
+    a single window using plt.subplot().
+    Grayscale images can be displayed using different mappings (on a RGB monitor,
+    every value needs to be mapped to a RGB triplet). Pyplot defaults to a color map
+    named viridis, but often it is preferable to use a grayscale color map. This can be set
+    with an additional argument to plt.imshow, like plt.imshow(I, cmap=’gray’).
+    Question: Why would you use different color maps?
+    Answer:
+    """
     print(image.shape)
-    #uz.imshow(image[50:200, 100:400, 2])
+    uz.imshow(image[50:200, 100:400, 2])
 
-# Convert one part of image to grayscale
 def one_d(startx: int, endx: int, starty: int, endy: int, image:npt.NDArray[np.float64]) -> None:
+    """
+    You can also replace only a part of the image using indexing. Write a script that
+    inverts a rectangular part of the image. This can be done pixel by pixel in a loop or
+    by using indexing.
+    Question: How is inverting a grayscale value defined for uint8 ?
+    Answer:
+    """
+    inverted_image = image.copy() 
 
     for i in range(startx, endx):
         for j in range(starty, endy):
-            image[i, j, 0] = 1 - image[i, j, 0]
-            image[i, j, 1] = 1 - image[i, j, 1]
-            image[i, j, 2] = 1 - image[i, j, 2]
+            inverted_image[i, j, 0] = 1 - image[i, j, 0]
+            inverted_image[i, j, 1] = 1 - image[i, j, 1]
+            inverted_image[i, j, 2] = 1 - image[i, j, 2]
 
-    uz.imshow(image, 'Bridie head grayscale')
+    uz.imshow(image, 'Shid')
 
+def one_e() -> None:
+    """
+    Perform a reduction of grayscale levels in the image. First read the image from
+    umbrellas.jpg and convert it to grayscale. You can write your own function for
+    grayscale conversion or use the function in UZ_utils.py.
+    Convert the grayscale image to floating point type. Then, rescale the image values
+    so that the largest possible value is 63. Convert the image back to uint8 and display
+    both the original and the modified image. Notice that both look the same. Pyplot
+    tries to maximize the contrast in displayed images by checking their values and
+    scaling them to cover the entire uint8 interval. If you want to avoid this, you need
+    to set the maximum expected value when using plt.imshow(), like plt.imshow(I,
+    vmax=255. Use this to display the resulting image so the change is visible.
+    """
+    print("todo")
     
 def main() -> None:
     excercise_one()