uz_assignments/assignment2/solution.py

import numpy as np
import numpy.typing as npt
from matplotlib import pyplot as plt
import random
import cv2
import uz_framework.image as uz_image
import uz_framework.text as uz_text
import os

#################################################################
# EXCERCISE 1: Exercise 1: Global approach to image description #
#################################################################

def ex1():
    #one_a()
    #one_b()
    #one_c()
    distances, selected_distances =  one_d('./data/dataset', './data/dataset_reduced/', 10)
    one_e(distances, selected_distances)

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
    should also work on other color spaces. The resulting histogram is stored in a 3-D
    matrix. The size of the resulting histogram is determined by the parameter n_bins.
    The bin range calculation is exactly the same as in the previous assignment, except
    now you will get one index for each image channel. Iterate through the image pixels
    and increment the appropriate histogram cells. You can create an empty 3-D numpy
    array with H = np.zeros((n_bins,n_bins,n_bins)). Take care that you normalize
    the resulting histogram.
    """
    lena = uz_image.imread('./data/images/lena.png', uz_image.ImageType.float64)
    lincoln = uz_image.imread('./data/images/lincoln.jpg', uz_image.ImageType.float64)
    lena_h = uz_image.get_image_bins_ND(lena, 128)
    lincoln_h = uz_image.get_image_bins_ND(lincoln, 128)
    print(uz_image.compare_two_histograms(lena_h, lincoln_h, uz_image.DistanceMeasure.euclidian_distance))
    return lena_h 

def one_b() -> None:
    """
     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.
     Function implemented in uz_framework
    """
    return None

def one_c() -> None:
    """
    Test your function
    Compute a 8×8×8-bin 3-D histogram for each image. Reshape each of them into a
    1-D array. Using plt.subplot(), display all three images in the same window as well
    as their corresponding histograms. Compute the L2 distance between histograms of
    object 1 and 2 as well as L2 distance between histograms of objects 1 and 3.

    Question: Which image (object_02_1.png or object_03_1.png) is more similar
    to image object_01_1.png considering the L2 distance? How about the other three
    distances? We can see that all three histograms contain a strongly expressed component (one bin has a much higher value than the others). Which color does this
    bin represent
    Answer:
    """
    IM1 = uz_image.imread('./data/dataset/object_01_1.png', uz_image.ImageType.float64)
    IM2 = uz_image.imread('./data/dataset/object_02_1.png', uz_image.ImageType.float64)
    IM3 = uz_image.imread('./data/dataset/object_03_1.png', uz_image.ImageType.float64)
    N_BINS = 8

    H1 = uz_image.get_image_bins_ND(IM1, N_BINS).reshape(-1)
    H2 = uz_image.get_image_bins_ND(IM2, N_BINS).reshape(-1)
    H3 = uz_image.get_image_bins_ND(IM3, N_BINS).reshape(-1)
    
    fig, axs = plt.subplots(2,3)
    fig.suptitle('Euclidian distance between three images')

    axs[0, 0].imshow(IM1)
    axs[0, 0].set(title='Image1')
    axs[0, 1].imshow(IM2)
    axs[0, 1].set(title='Image2')
    axs[0, 2].imshow(IM3)
    axs[0, 2].set(title='Image3')

    axs[1, 0].bar(np.arange(N_BINS**3), H1, width=3)
    axs[1, 0].set(title=f'L_2(h1, h1) = {np.round(uz_image.compare_two_histograms(H1, H1, uz_image.DistanceMeasure.euclidian_distance), 2)}')
    axs[1, 1].bar(np.arange(N_BINS**3), H2, width=3)
    axs[1, 1].set(title=f'L_2(h1, h2) = {np.round(uz_image.compare_two_histograms(H1, H2, uz_image.DistanceMeasure.euclidian_distance), 2)}')
    axs[1, 2].bar(np.arange(N_BINS**3), H3, width=3)
    axs[1, 2].set(title=f'L_2(h1, h3) = {np.round(uz_image.compare_two_histograms(H1, H3, uz_image.DistanceMeasure.euclidian_distance), 2)}')

    plt.show()

def one_d(directory: str, reduced_directory: str, n_bins: int):
    """
    You will now implement a simple image retrieval system that will use histograms.
    Write a function that will accept the path to the image directory and the parameter
    n_bins and then calculate RGB histograms for all images in the directory as well as
    transform them to 1-D arrays. Store the histograms in an appropriate data structure.
    Select some image from the directory dataset/ and compute the distance between
    its histogram and all the other histograms you calculated before. Sort the list according to the calculated similarity and display the reference image and the first
    five most similar images to it. Also display the corresponding histograms. Do this
    for all four distance measures that you implemented earlier.
    Question: Which distance is in your opinion best suited for image retrieval? How
    does the retrieved sequence change if you use a different number of bins? Is the
    execution time affected by the number of bins?
    """
    img_names = os.listdir(reduced_directory)
    methods=[uz_image.DistanceMeasure.euclidian_distance, uz_image.DistanceMeasure.chi_square_distance,
            uz_image.DistanceMeasure.intersection_distance, uz_image.DistanceMeasure.hellinger_distance ]
    imgs=[] 
    hists=[]
    selected_dists=[]
    for i in range(len(img_names)):
        imgs.append(uz_image.imread(f'{reduced_directory}/{img_names[i]}', uz_image.ImageType.float64))
        hists.append(uz_image.get_image_bins_ND(imgs[i], n_bins).reshape(-1))
    for method in methods:
        fig, axs = plt.subplots(2, len(imgs))
        fig.suptitle(f'Comparrison between different measures, using:{method.name}')
        distances = []
        for i in range(len(hists)):
            distances.append(uz_image.compare_two_histograms(hists[0], hists[i], method))

        indexes = np.argsort(distances)
        selected_dists.append(distances)

        for i in range(len(imgs)):
            axs[0, i].imshow(imgs[indexes[i]])
            axs[0, i].set(title=f'{img_names[indexes[i]]}')
            axs[1, i].bar(np.arange(n_bins**3), hists[indexes[i]], width=2)
            axs[1, i].set(title=f'd={distances[indexes[i]]}')

        plt.show()

    img_names = os.listdir(directory)
    h_image = uz_image.get_image_bins_ND(imgs[0], n_bins).reshape(-1)
    all_dists = [[] for _ in range(len(methods))]

    for i in range(len(img_names)):
        im = uz_image.imread(f'{directory}/{img_names[i]}', uz_image.ImageType.float64)
        h = uz_image.get_image_bins_ND(im, n_bins).reshape(-1)
        for j in range(len(methods)):
            all_dists[j].append(uz_image.compare_two_histograms(h_image, h, methods[j]))
    
    print(all_dists)
    return all_dists, selected_dists

def one_e(distances: list, selected_dists: list):
    """
    You can get a better sense of the differences in the distance values if you plot all
    of them at the same time. Use the function plt.plot() to display image indices
    on the x axis and distances to the reference image on the y axis. Display both the
    unsorted and the sorted image sequence and mark the most similar values using a
    circle (see pyplot documentation)
    """
    methods=[uz_image.DistanceMeasure.euclidian_distance, uz_image.DistanceMeasure.chi_square_distance,
            uz_image.DistanceMeasure.intersection_distance, uz_image.DistanceMeasure.hellinger_distance ]

    for i in range(len(distances)): 
        fig, axs = plt.subplots(1, 2)
        fig.suptitle(f'Using {methods[i].name}')
        indexes = np.arange(0, len(distances[i]) , 1)
        makevery_indexes = []

        for j in range(len(distances[i])):
            print(distances[i][j])
            if distances[i][j] in selected_dists[i]:
                makevery_indexes.append(j)

        axs[0].plot(indexes,distances[i],markevery=makevery_indexes,  markerfacecolor = "none", marker = "o", markeredgecolor = "orange")
        axs[1].plot(indexes,np.sort(distances[i]),markevery=makevery_indexes,  markerfacecolor = "none", marker = "o", markeredgecolor = "orange")
        plt.show()

############################
# EXCERCISE 2: Convolution #
############################

def ex2():
    two_b()

def two_b():
    """
    Implement the function simple_convolution that uses a 1-D signal I and a kernel
    k of size 2N + 1. The function should return the convolution between the two.
    To simplify, you only need to calculate the convolution on signal elements from
    i = N to i = |I| − N. The first and last N elements of the signal will not be
    used (this is different in practice where signal edges must be accounted for). Test
    your implementation by loading the signal (file signal.txt) and the kernel (file
    kernal.txt) using the function read_data from a2_utils.py and performing the
    operation. Display the signal, the kernel and the result on the same figure. You can
    compare your result with the result of function cv2.filter2D. Note that the shape
    should be generally identical, while the values at the edges of the results and the
    results’ offset might be different since you will not be addressing the issue of the
    border pixels.
    Question: Can you recognize the shape of the kernel? What is the sum of the
    elements in the kernel? How does the kernel affect the signal?
    """
    signal = uz_text.read_data('./data/signal.txt')
    kernel = uz_text.read_data('./data/kernel.txt')
    convolved_signal = uz_image.simple_convolution(signal, kernel)

    cv2_convolved_signal = cv2.filter2D(signal, cv2.CV_64F, kernel)

    plt.plot(convolved_signal, color='tab:green', label='Result')
    plt.plot(cv2_convolved_signal, color='tab:red', label='cv2')
    plt.plot(signal, color='tab:blue', label='Original')
    plt.plot(kernel, color='tab:orange', label='Kernel')
    plt.legend()
    plt.show()


    
# ######## #
# SOLUTION #
# ######## #

def main():
    #ex1()
    ex2()

if __name__ == '__main__':
    main()