week 1

.gitignore

+**/.DS_Store
+**/__pycache__*

Week01/total_variation_exercise.ipynb

+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Total variation exercise"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import numpy as np\n",
+    "import skimage.io\n",
+    "from scipy.ndimage import gaussian_filter"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Function to compute total variation\n",
+    "def total_variation(im):\n",
+    "    '''\n",
+    "    Computes the total variation of an image.\n",
+    "    \n",
+    "    Parameters\n",
+    "    ----------\n",
+    "    im : ndarray\n",
+    "        Image.\n",
+    "    \n",
+    "    Returns\n",
+    "    -------\n",
+    "    float\n",
+    "        Total variation of the image.\n",
+    "    '''\n",
+    "    return np.abs(im[:-1] - im[1:]).sum() + np.abs(im[:,:-1] - im[:,1:]).sum()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Total variation of original image: 4.766e+09\n",
+      "Total variation of smoothed image: 1.606e+09\n",
+      "Total variation is reduced by: 3.16e+09\n"
+     ]
+    }
+   ],
+   "source": [
+    "# Read data\n",
+    "in_dir = '../data/week1/'\n",
+    "im = skimage.io.imread(in_dir + 'fibres_xcth.png').astype(float)\n",
+    "\n",
+    "# Compute total variation\n",
+    "tv_im = total_variation(im)\n",
+    "\n",
+    "# Smooth the image\n",
+    "sigma = 2\n",
+    "im_g = gaussian_filter(im, sigma)\n",
+    "\n",
+    "# Compute total variation\n",
+    "tv_im_g = total_variation(im_g)\n",
+    "\n",
+    "# Print the results\n",
+    "print(f'Total variation of original image: {tv_im:0.4g}')\n",
+    "print(f'Total variation of smoothed image: {tv_im_g:0.4g}')\n",
+    "print(f'Total variation is reduced by: {tv_im-tv_im_g:0.4g}')    \n"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "AIAcourse",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.10.9"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}